g7nbp - random noise

does Michael Gove read my blog?

2012-01-12T09:23:00.002Z

Followers of my blog will hopefully remember the post I made back in October ( http://g7nbp.blogspot.com/2011/10/ict-is-not-cs.html ) Where I commented on the failures of the UKs current ICT curriculum to inspire children in the field of computing.

Yesterday Michael Gove called the current ICT curriculum "demotivating and dull". He will begin a consultation next week on the new computing curriculum.
He said this would create young people "able to work at the forefront of technological change".

He went on to say "Instead of children bored out of their minds being taught how to use Word or Excel by bored teachers, we could have 11-year-olds able to write simple 2D computer animations,"

(source : http://www.bbc.co.uk/news/education-16493929 )

This is brilliant news indeed - if schools are able to back it up with good quality teaching. Sadly, in my experience a number of schools fail to teach even the existing curriculm particularly well and would require significant help with teaching a more technology rich version.

I shall continue to watch progress in this area with interest, especially as I am currently putting together a technology learning package aimed at 11-16 year olds based around a lot of the technology now being advocated as the future of ICT.

Watch this space...

Today we are be mostly building robots

2012-01-01T20:08:00.001Z

Emily has started construction of the robotic arm project. More pix and vids shortly.

Beacon back on

2011-12-21T07:20:00.003Z

28MHz MEPT is back on as Im now back from my diving trip in Egypt.

Its currently warming up so freq is 28.000785ish MHz and will wander for best part of the day before it decides where it wants to be.

Taking no chances

2011-12-08T10:35:00.001Z

As the isobars stack up ever closer and the cat gets fed up of being blown off the window sill, its time to start lowering some of the antennas here.

An electronics kit for Christmas?

2011-11-15T12:29:00.001Z

About this time of year I am often asked by friends who have children about the same age as my daughter "Which electronics kit should I buy for my child?"

A good question as there is a bewildering array of them out there a very quick search on Amazon brings back over a thousand results, and add to that ebay, other online sellers and the offerings of the high street toy shops and it becomes a huge number.

So - how to chose??

Well, You have to weigh up the level of experience your child has - if they are already past the basics and can solder then there is a wide range of specific purpose kits out there eg:

They are usually good value, Costing from a few pounds up to a few tens of pounds - (this particular one costs about £10 from here). Most of them are simple enough to get working and to stand some rough and ready assembly techniques. Lots to choose from - but look out for well made kits with good documentation. A personal favourite manufacturer is Vellman who generally seem one of the better manufacturers, though there are many.

But... The chances are that if your child is already advanced enough to be at this stage, they will be telling you what they want rather than leaving you guessing. While these sorts of kits are a good introduction to soldering, its also important to note that actually these sort of kits actually teach you very little about actual electronics - much the same way as painting by numbers teaches you little about painting. Its simply a case of finding the right component from the list and soldering it into the holes on the board. Few kits go beyond a hurried circuit diagram and do not properly explain any of the underlying workings of the circuit.

On the whole - great for those wanting to learn to solder, or for the more advanced builder , but best to avoid if your child is a newcomer to electronics

Instead, aim for a multi project kit which includes good learning materials teaching the basics of electronic circuit design in a progressive way - what is generally though of as an "electronics kit" rather than a "project".

Of these, what I call the "wire - spring linkup " electronics kits are by far the most common.

They range from small, inexpensive kits with a limited number of options such as this one shown on the left, to very comprehensive kits similar to the one shown on the right which can cost hundreds of pounds

I call them the "wire - spring linkup" type because of the way you construct the circuits you are building. The components themselves are in fixed locations within the kit and to join them together you link them together by trapping the ends of insulated wires in spring loaded terminals which each component is equipped with.

These kits generally offer great value for money - though the maxim about getting what you pay for is still applicable. The better ones generally cover the basic fundamentals of electronics - the beginnings of ohms law, how components work and how they relate to each other to make a circuit. The more comprehensive ones have some interesting circuits too - which is important as your child will want to see something useful at the end of all that wire linking.

They do however have a downside. Because the components are in fixed locations on the board, when you are linking them up, the resulting rats nest of wires will have no resemblance to the circuit diagram you are following. Fault finding can be difficult, and generally understanding what is going on is much harder.

If I personally had to chose a particular type of kit to recommend overall, it would be one like this:

(This is the actual one I bought my daughter)

Why?? Well it comes down simply to this, you lay out the components and the links between them EXACTLY as it looks in the circuit diagram:

Brilliant!!

There are a range if kits by Snap Circuits, and other manufactures of this type ranging from a few tens of pounds up to a few hundreds .

While I cant comment on other manufacturers, the manuals produced in the genuine Snap Circuits kits are some of the best I have ever seen and closely follow the learning work which my daughter does at school. They are designed to be used by both learner and tutor - which is important as you will be taking a semi-active roll in helping your child with this right?? ;)

NB: links and images are not intended to endorse any particular product / supplier - they are just the most convenient way of illustrating this post - if any manufactures / suppliers object to my use of their images etc please leave me a message and I will edit accordingly.

Haynes in the oven.

2011-11-07T08:50:00.001Z

Not a good start to Monday, it seems I left the haynes manual for the 4x4 on the bonnet yesterday (perils of working on car till its dark). 98% humidity overnight, plus a light frost means I had to chip it off the bonnet this morning. Duh!

2011-11-04T15:18:00.002Z

Medium term drift seems to be settling down a bit now. The mark and space on my signal is about 6Hz, so as can be seen from the 15min grab I took - compared to te datum line I inserted it looks as though it wanders +/- 2Hz over the time frame.

Carrying out a similar test against WWV frequency stanards on assorted bands and against my 10MHz standard shows a minimum +/- 1Hz drift attributable to the RX itself so Im reasonably pleased with that.

Just 48mW :)

2011-11-03T14:48:00.000Z

My replacement 50R termination arrived yesterday (The magic smoke escaped from the old one, it didnt like 30 watts for some reason!) ;)

So I decided to re-measure the beacon output as the usual x10 scope probes dont always give a good reading from the dummy load terminals.

But, results were much as previous - Im seeing 4.4v p2p - which into 50R is just a shade over 48mW.

To give some perspective - thats about the same output as a bright LED!

But... its enough!

Thats my 48.4mW into a 1/2wave zepp at about 6mAGL - with 10m of RG8 - so probably closer to 45mW at the antenna - arriving over with Bill - W4HBK in Florida.

W4HBK::

Grid Square

EM60kj

US State

Florida

US County

Santa Rosa

Bearing

285.7° WNW (from G7NBP)

Distance

4355.8 mi (7010.1 km)

Sporadically active on 10m

2011-11-01T16:22:00.000Z

OK - Ive slug up a very rough horizontal zepp for 10m - main lobes roughly E/W from here.

Freq currently is 28.000810 MHz - ie tune to 28.0MHz USB it will be a 810Hz tone

Currently 12wpm call in CW - followed by 10x callsign in QRSS6 FSK

and the results are in...

2011-11-01T13:05:00.000Z

Well.... 3 hours of ten minutely data gathering done.

Results are.... interesting!

First the graphs:

And now the raw data:

time	ambient C	xtal C	diff C	10 min change C	freq Hz	relative drift over 10mins	total drift from power-on
09:30	23.4	27.6	4.2		0	0
09:40	23.8	28.2	4.4	0.2	727	0
09:50	23.9	29.8	5.9	1.5	737	10	10
10:00	23.9	31.1	7.2	1.3	754	17	27
10:10	24	32.1	8.1	0.9	761	7	34
10:20	23.9	33.1	9.2	1.1	771	10	44
10:30	24	33.8	9.8	0.6	777	6	50
10:40	24	34.4	10.4	0.6	784	7	57
10:50	23.7	35	11.3	0.9	790	6	63
11:00	23.6	35.3	11.7	0.4	793	3	66
11:10	23.5	35.8	12.3	0.6	797	4	70
11:20	23.4	36	12.6	0.3	801	4	74
11:30	23.4	36.2	12.8	0.2	802	1	75
11:40	23.3	36.3	13	0.2	804	2	77
11:50	23.3	36.5	13.2	0.2	807	3	80
12:00	23.3	36.6	13.3	0.1	808	1	81
12:10	23.3	36.7	13.4	0.1	810	2	83
12:20	23.3	36.8	13.5	0.1	810	0	83
12:30	23.3	36.8	13.5	0.0	810	0	83

So...

After 3 hours the temp seems to have stabilised out as does the freq, and the temp is lower than in previous tests.

Its still however showing better part of 100Hz drift over 3 hours from power on until it settles down.

Thats fine if you are going to be leaving the beacon running for days at a time, but if you are going to be turning on and off for a few hours at a time thats going to get somewhat annoying. It also means that during warm up you could potentially end up crashing into someone elses signal.

Based on this, as I was discussing with G0CER yesterday, I think the trick here is NOT to switch off the beacon. (Duh!) Yes I realise the licensing implications here, what I suggest is leaving it running 24:7, but when not present in the QTH to switch the output into a dummy load - that way no (in theory!) RF radiates beyond the boundary of the property whilst the beacon is unattended.

Im also now looking at active cooling - ie popping a heatsink onto the lid of the box and then running some PWM proportional to the temp into a fan to try and hold the temp at a lower constant temp - though as others have commented on the GQRP list - it would be better to address the electronic design first with negative co-efficient caps etc.

I think Ive gone about as far as Im going to go for now with thermal tests. The bottom end of 10m isnt exactly crowded with QRSS sigs, so I guess I can afford to let it wander a bit for now.

Next priority is actually getting a signal out - so Im just cutting a very hurried 10m Zepp to sling out for now. It will be horizontal pola and be strung up roughly north south. Expected main lobes should (fingers crossed!) be heading in roughly the right directions.

More later.
.

Xtal insulation

2011-11-01T09:57:00.003Z

Polystyrene added around the xtal. This is of course an imperfect solution as the thermo-couple is in contact with the diecast box and will thus be not only reading the case temp but will be radiating some of that heat inside the polystyrene cube.

Tests underway now with this mod and bead jacket between inner and outer box. Ons at 10 min intervals.

Graphs and stats later.

28MHz QRSS beacon - further tests

2011-11-01T09:13:00.002Z

Sadly no time last night for anything particularly scientific, but having observed temperatures about a dozen times last night and again this morning it looks like this:

Condx = 7.3v supply, in diecast box, in outer box, NO beads, sitting on rack.

probe temp holds at around 7C higher than ambient temp.

As the room temp in here varies between 23 - 26C depending on if lights and monitors are on - the resulting swing on the after an hour or so from power on is 30.4 - 33.8 (from observation).

Heating appears to be significantly less than with a 12v supply.

What I plan to do now is:

a) cut a polystyrene block to fit around the xtal inside the diecast box to reduce temperature changes inside the box from any convection etc

b) re-add the beads to provide thermal insulation from room changes.

..... Oh... and try and get a wire antenna up today :)

28MHz QRSS beacon

2011-10-30T20:58:00.000Z

Well, as promised elsewhere - a quick update on where I am with the 10m QRSS beacon project.

I decided not to bury it! Instead its going to live on the rack here in the shack / server room. Temps in here are fairly constant, but I decided to try adding a thick layer of thermal insulation around the beacon to elevate its temp to help buffer it from minor temp changes in here. This may not be ideal!

Read on...

Here we see the completed beacon PCB inside a diecast box.

The device poking through the lower edge of the box is a thermocouple. It is directly above the oscillator crystal - so should give a direct readout of the temperature inside the box nearest the xtal.

This can be seen in more detail in this image.

Here we see it with the lid on the diecast box, inside its outer casing. The thermocouple is showing at that stage about 4 degrees above room temp - and a current drain of 90mA.

Now we see the digital thermometer mounted on the front panel, along with keyswitch and power LED.

The next stage was adding the thermal insulation - in this case polystyrene beads.

.... until it looks like this.

And then we quickly screw the lid down before all the beads escape!

And there it is sat on the rack.

So, tests began about 5 hours ago. Once every five minutes I recorded the xtal temp, and the frequency in Hz (audio) with my RX set to 28.000 MHz CW.

The beacon is at present TXing into a dummy load with lose coupling to the RX. (Im still torn between a half wave end fed vert and a halo when I do get an antenna up - but thats another story!)

Im using my usual studio quality soundcard (24bit) to sample the recovered audio from the RX, and used Baudline (an audio analysis tool) to take measurements of the frequency of the mark and space tones. This provides an accuracy roughly on a par with my frequency counter, (limited by the unknown drift on my RX in fact) but makes it easier to read the changing frequencies brought about by the FSK which on a counter is a bit of a pain.

yes - the FSK is a bit on the high side - about 8Hz - I was aiming for 5 but with the lid on and temp up the FSKing is also slightly increased.

These were the figures for the first 3 hours:

(Raw data follows.)

mins temp C freq Hz
0     25      760
5     25.6    748
10    26.9    741
15    28.2    740
20    29.4    742
25    30.5    748
30    31.7    758
35    32.5    766
40    33.3    769
45    34.2    772
50    34.9    775
55    35.5    778
60    36.2    782
65    36.8    787
70    37.2    792
75    37.7    794
80    38.2    799
85    38.5    801
90    38.9    805
95    39.3    809
100   39.5    811
105   39.8    815
110   40.1    817
115   40.3    820
120   40.5    822
125   40.8    824
130   40.9    826
135   41.1    828
140   41.2    830
145   41.3    832
150   41.5    833
155   41.6    834
160   41.8    835
165   41.9    837
170   42.0    839
175   42.1    839
180   42.1    840

After 3 hours I stopped taking five minutely readings, and checked sporadically.

After 5 hours the Xtal temp had reached 43.5cand the frequency had reached 858Hz thats around 100Hz moved for around 20c temp change.

Although the values where beginning to flatten off, I pulled the plug after 5 hours as I feel that the thermal insulation is perhaps just a little too efficient!

Looking at the mark and space data on the display it was clear that once the xtal temp was past 33c that there was slightly more 1Hz jitter on the signal. No tests done to confirm this or the cause yet - but Im guessing that the PA transistor is sitting a fair bit warmer than the xtal and may be running away a little.

My main worry though is that as this will be operating as a MEPT (Manned Experimental Propagation Transmitter) to remain within licencing conditions it will spend some quite sizeable times powered off when Im not physically here. The long ramp up time to stability is not going to be condusive to a device that is turned on and off frequently. (As I am writing this the temp has dropped by over 3 degrees in 8 minutes, showing that cool down is much swifter than warm-up).

I think I may need to add a simple heater circ to the diecast box for more rapid warm ups, and to limit the upper temp to about 30c.

More tests will follow...

ICT is not CS

2011-10-22T15:24:00.000+01:00

Its been a while since I did a wordy post, but having just watched a short video from the beebs archive, its prompted me to comment on something I feel strongly about:

ukict != cs;

Sadly thats not going to mean a lot to most people, and therein lies my point.

In my opinion the current UK schools curriculum subject ICT is not fit for purpose. It is simply not a substitute for teaching Computer Science. It is creating a generation of mindless point and clickers.

And it seems Im not alone in this worry. Have a look at http://news.bbc.co.uk/1/hi/programmes/newsnight/9612063.stm

Some schools even struggle to teach the basic ICT curriculum particularly well, but in reality what they need to be looking at is a return to teaching Computer Science. Scary - but its time for a rethink.

When I was growing up, if I wanted to play a computer game, I had to write it. Yes really write it - type in the code, line by line. I realise that for most people under the age of 35 thats kind of shocking now, but really thats what we had to do. The thing is, the need to do that, to develop your own software is now long gone. These days you just download an app yes??, or bung in a CD.....?

But ask yourself - where do these apps come from??? Someone has to write them.... That would be the software developers.

At school us forty-something developers did "computer studies". We learned all the basics (pun possibly intended!) of the nuts and bolts of how to write software. We also covered fundamentals such as boolean algebra and binary math. Yes, I know they are mentioned in the current curriculum - but thats it - they are just mentioned.

There is a whole generation now who are, and probably only ever will be IT consumers rather than IT creators. We are educating the masses to blindly use software created by others rather than innovating new software ourselves.

We have to tackle this with our current teenagers or risk a huge skills gap in the future.

As followers of my assorted blogs will know, we have an "Emily". She is our daughter, and we think she is amazing. In a lot of ways however, she is very typical. Very typical of a bright 13 year old. She does well at school, but would take exception to being thought of as "Geeky".

The thing is that despite this non-nerd status, with a few sessions of goal based,workshop style teaching at home and a LOT of support on the practicalities of turning "what-if" into "how-to", Emily is able to turn out things like this:

For those of you who havent already seen it, thats live and historical data coming from a set of network connected sensors (which emily mainly designed and built) being collected, stored, graphed and pushed back out to the web using software that Emily herself wrote with very little help.

see http://myweatherblog.wordpress.com/livedata/ - you can read about some of the technology behind it here : http://myweatherblog.wordpress.com/equipment-4/

With project-based workshops and goal-based motivation as the teaching method Emily has gained a good enough basic grasp on simple digital electronics, networking, programming and databases to achieve all this in a little over 12 months - probably equivalent to 3 terms classroom time.

If im honest, I would say with the same level of help MOST children in Emilys class at school would be able to cope with the key aspects of how this project works and as a group project would find it both attainable and enjoyable.

The import thing here is that actually projects like this tick so many of those all important ticky boxes for cross curricular attainmnet and key skills that it makes your hair curl!

So what is the current ICT curriculum asking them to do? Well, a lot of it focusses on skills like how to open a spreadsheet, create a powerpoint slide, turn the computer on and off without breaking windows. All valid skills - as an IT consumer - but not exactly inspirational for the next generation of Uber Developers.

An understanding of the mechanics of computing is not something we can just leave until AS level and hope that a few "bright" ones will stick with ICT long enough to want a career out of it. And a couple of lessons spent creating a web page with WYSIWG editor is NOT learning about programming. The science part of computing has to be there from the earliest days of learning.

So... what can we as parents do? Well, I suggest you buy one of the many workbooks available for the current curriculum and make sure that your childs school is teaching the existing curriculum well. But also to see what is not being taught.

We can of course lobby the government to rethink computing education in the UK - but educational reform tends to be a slow process, so we need to think about the short term too.

If you have the skills, you could do what a lot of us do and not only help our own children, but to volunteer to help run afterschool classes and groups to bring technology to the kids.

But, if I had to chose something to say to all parents to help their kids WANT to take a deeper interest in IT and technology - I suggest the age old way of teaching kids techy stuff - make it fun!

Download a copy of Scratch developed by the Lifelong Kindergarten Group at the MIT Media Lab (its free! - and windows/mac/linux flavours) and buy them a copy of this: Scratch programming for Teens

If you were paying close attention to the BBC video at the top of this post you might recognise the above image.

To pinch a quote from the scratch website:

"Scratch is a programming language that makes it easy to create your own interactive stories, animations, games, music, and art -- and share your creations on the web.

As young people create and share Scratch projects, they learn important mathematical and computational ideas, while also learning to think creatively, reason systematically, and work collaboratively."

Scratch is the Lego(tm) of the programming world. You literally drag and drop building blocks of code together graphically to add interactivity to objects. Its quick, easy and intuitive. But it is based on real programming constructs - decisions, loops, conditionals, variables, objects and actions.

Scratch was the first programming language Emily learned. I didn't teach it to her. She learned it. I simply installed a copy on her PC and said "hey - check this out - its kinda good". And she got it... She just Got It. Yes, I've offered the occasional bit of help now and then - and perhaps suggested she look again to see if the was a simpler way of doing something. But Scratch teaches itself.

Based on what She has learned, Emily now programs in varying degrees of depth - Arduino, C, Processing, PHP, MySQL and the Linux shell Bash. She still has a lot to learn, but she has the fundamentals and thats the key. She knows how to do useful stuff, and knows how to find out stuff she doesn't know. And that the core skill of anyone working in software design, or electronics, or engineering etc etc etc.

And if you are thinking that OK Scratch looks cool but what does it lead to?? - well... as commented above Emilys grasp of programming constructs come from her introduction via scratch, but sticking with graphical block programming for a moment further - the concept has been carried forward - again via MIT and Google - to produce App Inventor - the graphical development language for Android based mobile phones and other devices.

App Inventor will be Emily's development platform for a whole host of new projects over then next couple of years.

So Go ON! Get your kids into something thats going to change not just their world - but everyones. Who knows, the next app you download to your phone might have been written by your son or daughter!

Some more links (from Emily's bookmarks) to play with:

http://makezine.com/
http://arduino.cc/
http://mindstorms.lego.com/en-us/Default.aspx
http://www.adafruit.com/blog/about/
http://www.oomlout.com/a/
http://www.modk.it/
http://processing.org/
http://hackaday.com/
http://www.instructables.com/

Ts140 repair

2011-10-21T15:17:00.000+01:00

I had a spare few mins this afternoon so I thought I would tackle the intermittent audio fault on my TS140. Previously I had traced it down to the external speaker socket on the rear - it seemed to be dependant on the angle of the audio jack as to weather audio came out of the external speaker - but if unplugged audio did not always return to the internal speaker via the make/break contacts in the socket.

I was hoping a squirt of switch cleaner was going to solve the problem, but no - as I feared it was a broken joint on the PCB under the socket.

Every last nut and bolt out to get to it and the zillion and one mini connectors undone before I could lift the PCB to get to solder the joint. Im not usually squeamish when it comes to repairs, but this one had me sweating! The TS140 was built between the times when you took your rig apart with a hammer, and recent tech where basically you dare not take a bolt out of the case - (and even if you did what would you change?) So it has an overly large number of interconnections and lots of scope for making existing dry joints worse.

Thankfully it now seems happy - Even with the lid on!

Morse wine

2011-10-10T21:49:00.001+01:00

Todays discovery

2011-09-22T21:20:00.000+01:00

Emily has updated the equipment information section of her blog ( http://myweatherblog.wordpress.com/equipment-4/ ) to reflect the recent sensor array changes - a full pdf download report with lots more pix, circuit diags and source code will be along shortly...

Weekly graphs added

2011-09-17T21:38:00.001+01:00

Weekly graph data has now been added to Emily's sensor project - http://myweatherblog.wordpress.com/livedata

Arduino - HTF3223 Humidity Sensor

2011-09-13T16:49:00.000+01:00

Over the past six months or so I have been helping my daughter with a remote mounted sensors project to supplement the info from her weather station on her blog. Light and temperature sensing via the analogue ports has presented no problems (LDR and TMP36), but when it comes down to humidity sensing its a bit more complex.

Although you can buy some inexpensive resistive humidity sensors, these are not suitable for DC reading and have to be read using an AC waveform at a few KHz to avoid eventual damage to the devices.

There are ready made humidity sensor system which use SPI/I2C bus communication which give very good results, but looking at them,they tend to be a little pricey and the required source code is a bit beyond the level of Arduino coding Emily is happy with.

After a LOT of digging I came up with the Humirel HTF3223 Sensor.

Unlike other sensors, it provides an analogue value out which is linear with the relative humidity, but rather than a voltage it outputs a variable frequency square wave at between 8 and 10KHz.

So - how are we going to convert frequency to something useful??

Well there is a frequency counter lib available, but for a top frequency of around 10KHz its a bit like using a sledgehammer to crack a nut.

After a bit of googling I found several examples of using the pulsein function. The following code gives a very quick example of reading the frequency from the humidity module, and using a simple conversion formula, convert it to relative humidity.

/*

Humidity sensor test for HTF3223 humidity sensor

By G7NBP - Chris Williams

V0.0.1 28th - May 2011

The inexpensive HTF3223 sensor (ebay etc) provides good accuracy relative humidity
sensor readings (typically +/- 5%) and has a simple linear output.

Its output however is in the form of a variable frequency proportionate to the humidity.

The formula for convertion is RH = (9740/Freq)/18

Although it is possible to use the frequency library to collect the frequency, this
is somewhat overkill as the freq is not expected to be above 10KHz.

Instead the pulseIn function is used and frequency averaged over 4096 counts.

connect H pin on HTF3223 to digital pin 7

*/

const int hpin = 7; // the sensor pin

void setup() {
Serial.begin(9600);
pinMode(hpin, INPUT);

}

void loop() {
long sensorValue = getFrequency(hpin); // get the raw sensor frequency
long humidity = convertToRH(sensorValue); // convert it to RH%
Serial.print("S:");
Serial.print(sensorValue, DEC);
Serial.print(" H:");
Serial.print(humidity, DEC);
Serial.println("%");
delay(3000);

}

long getFrequency(int pin){
#define SAMPLES 4096
long freq = 0;
for(unsigned int j=0; j<SAMPLES; j++) freq+= 500000/pulseIn(pin, HIGH, 250000);
return freq / SAMPLES;
}

long convertToRH(long sensorValue){
long rh = (9740-sensorValue)/18;
return rh;
}

Can you guess what it is yet - the update

2011-09-11T13:00:00.000+01:00

Well the more astute visitors to the site correctly identified the mystery object as Emilys weather sensor array project.

The device designed and built mainly by Emily is an ethernet connected sensor array, measuring Light, Temperature and Relative Humidity.

There is of course, an Arduino lurking in there as the main device, along with the ethernet shield. Sensors are TMP36 for temperature, A simple LDR for light and an HF3223 Humidity sensor. All of these live in the top enclosure.

The lower enclosure and antenna system were added when it was discovered that the TMP36 sensors were somewhat prone to false readings when subjected to local high RF fields (the array is not too far away from my R7000 HF and UHF collinear antennas). Inside the enclosure is a modified RF pre-amp followed by a simple diode rectifier circuit feeding one of the analog inputs on the arduino - giving a relative filed strength measurement. This allows data which may be subject to false levels to be dropped when processing the data.

Data is collected via one of our servers every 60 seconds by making an http request (scripted in phpcli) to the ethernet shield on the arduino - results are returned from the sensors as a simple comma separated string. The phpcli script then saves the data - including the RF levels to a MySQL database.

The resulting livedata, and historical data is then processed using php and the GD image libs along with JPgraph to produce dynamic images in her blog site:

see : http://myweatherblog.wordpress.com/livedata/

There will be a full writeup with photos, hardware diagrams, networking info, description of making a "power over ethernet cable", arduino code, php and mysql etc on Emilys blog site shortly. I will post a crosslink when its finished

Congratulations to Emily on this fine piece of work - almost all the hardware, software, networking and database work was done by Emily herself. Brilliant effort and a great project over the summer holiday.

Can you guess what it is yet?

2011-09-01T13:26:00.001+01:00

Another bit of kit has gone up @ the g7nbp qth, can you guess what? All will be revealed shortly :)

Another change to Emilys' weather systems blog...

2010-12-16T11:02:00.001Z

Rather than pushing images up to the blog site three or four times a day, I am dropping in linkbacks to dynamically updated images on one of my servers. These will be embedded in static tabs off the main site.

The same process will also be applied to the daily observations data, and eventually to the live sensor data from the arduino weather project (more on this later!)

Em will then use the main blog area for comments and pictures etc.

Ive embedded a click-able link to the dynamic image over in my sidebar --->

More later :)

Auto processing and upload of sat images on Emilys blog site

2010-10-27T17:50:00.000+01:00

Unusually I found myself finishing my normal admin tasks an hour or so early, so Ive had a few spare mins to automate processing and upload of the sat images to Emilys blog site - http://myweatherblog.wordpress.com/

To avoid filling the blog with images Ive limited uploads to just those from NOAA15, which typically gives as about 3 good passes a day.

To make life easy Ive used a command-line php script to re-size the images down to 380pix width (about right for the site layout). It also extracts the image data automatically from the filename - ie the satellite name (in case I change it) AOS time in UTC and the type of image processing used. It then pushes the image to wordpress as a media upload and then builds a page dynamically around it and the extracted data. This is done using a standard XML-RPC call. (The script is called from the crontab at 15 min intervals throughout the day.)

Yes its much easier to just live update data on one of my servers - but this also serves as a proof-of-concept project demonstrating that it is possible to use some simple scripting even on a local desktop to push dynamic data onto what would be normally considered a static blog site.

If there is sufficient interest I will upload a few code examples.

ground post

2010-08-18T10:58:00.004+01:00

A couple of people have asked about the titlover ground post on my R7000 so here are a few pix during the concrete pour:

The base post is sunk about 1.2m into the ground, and extends another 1.5m above the ground line. It has a has a pivot bolt at the bottom which goes through the scaffolding pole, and a scaffolding clamp at the top which locks the pole in place when upright.

Here we see the plastic sleeve around the post (to allow it to be drawn out once the concrete has set) and some rubble to help keep it vertical while the postmix concrete was poured.

And thats it with 5 bags of postmix added... oh and a good does of water.

R7000 refurb finished

2010-06-28T09:25:00.004+01:00

After about six months of sporadic cleaning and testing the refurbishment project on my R7000 finally came to a close yesterday. The small tiltover mast has been rotated through 90 degrees to allow the antenna to "walk down" into the garden, and the meteo equipment has been moved onto a stand-off bracket about 1m down from the top to keep it clear of the radials.

Aside from testing resonance of the traps (vaguely inconclusive) I have not had chance yet to air test, mainly as I will need to replace or radically extend my primary coax run to reach the antenna - as although the antenna is only about 15m from the house the coax will probably now a total run length of about 65m to avoid cutting across the drive and patio. I plan to run up a few meters of coax later today and check how it loads up on each of the bands.

Still to do: Add some guy lines (its windy here!) and seal up all the joints with self-amalgamating tape once Im sure its resonant in the right parts of the bands.

Duh!

2010-03-04T12:18:00.003Z

Well, it seems you read my blogs more closely than I do!

Ive just had a mail from a friend pointing out that telling you to keep an eye on Emilys' weather blog, and then not including the URL does make it unnecessarily hard. I know some of you like a challenge, but I conceed that I perhaps should give it ;)

http://myweatherblog.wordpress.com/

As for infrequent blogging... Normal service will resume shortly, when work and my current OU commitments return to a more normal level.

2010-02-07T16:30:00.001Z

Hot off the press - NOAA15 pass @ 16:00 UTC today, our first test image off the WX Sat system :)

Keep an eye on Emily's weather blog for lots of further updates.

gMFSK getwx - a more finished script :)

2009-12-28T11:34:00.007Z

Well... I didnt expect this to be quite so popular :) I woke up to a full inbox this morning - hard to believe so many people found the script so quickly.

OK, I realise that not everyone who uses gMFSK is a php programmer, and somne people are a little wary of editing the cron tab, so Ive written out a script that does everything - ie: it checks if there is a recent local copy of the RSS xml and builds the weather data from that - only downloading from yahoo if more than 30 minutes (by default) have passed.

Ive added lots of comments so as a combination of the new script and reading the previous blog entry it should be very clear how this works. I hope it will lead you on to a bit more experimenting with other on-line RSS sources you may want to use.

enjoy:


#!/usr/bin/php
<?
/*  gMFSK getwx::

 A simple script to grab your local weather from the web to insert into F-key
 macros in the same way as $mycall $yourcall etc.

 This is a slightly more finished version of the test scripts recently published 
 on my blog. This version checks if it has a local copy with a recent datestamp 
 of the RSS data from yahoo - then builds a complete weather report from the cached
 data to save hitting yahoo every time the script is called.

 Yes it could be done more easilly using cron, but feedback from some users 
 has suggested that a self contained "easy" script is wanted

 Yes I could have used CURL - but a basic php_cli install doesnt always have
 CURL compiled in.

 to get the right url for your local yahoo weather vist weather.yahoo.com
 type in your location and hit return. When you get your local weather click
 on the orange RSS button and make a note of the URL. its the p=XXXXXXXXX bit that
 is important. Changing the u=f to u=c gets you metric results

 You need php_cli installed for this script to work eg: sudo apt-get install php5_cli

 save this script to your gMFSK directory, remember to chmod it +x to be executeable
 
 in one of the gMFSK function key windows add the command:

  $(/home/g7nbp/gMFSK/getwx)

 Remember to alter your path to point at wherever the file is saved. 


 Please feel free to experiment :)

 Written by g7nbp 28-12-2009
*/


// OK first a few variables
$pageurl =  "http://weather.yahooapis.com/forecastrss?p=UKXX1012&u=c";  // url of yahoo weather RSS feed 
$file = "wx.xml";         // the file to save the xml to
$update_time = 1800;         // period between getting updates down in seconds



if (file_exists($file)){   
 
 // the wx.xml file has been found :)
 $fileage =  time() - filemtime($file); // workout how old the local copy is
 if ($fileage >= $update_time){
  // local copy older than update_time - call the get_xml routine to read from website  
  get_xml();
 }

}else{ 
 // no the wx.xml file has not been found (first run??) so call the get_xml routine
 get_xml();
} 

// OK assuming nothing broke we can now work with the local copy :)


$rss =  simplexml_load_file($file); // open local copy

// Build the variables from the assorted yweather:something namespaces
$condx = $rss->xpath('//yweather:condition/@text');
$condx = ltrim(rtrim($condx[0])) ." ";

$pressure = $rss->xpath('//yweather:atmosphere/@pressure');
$pressure_units = $rss->xpath('//yweather:units/@pressure');
$pressure = ltrim(rtrim($pressure[0])) . $pressure_units[0];

$temp = $rss->xpath('//yweather:condition/@temp');
$temp_units = $rss->xpath('//yweather:units/@temperature');
$temp = ltrim(rtrim($temp[0])) ."°". $temp_units[0];

$windd = $rss->xpath('//yweather:wind/@direction');
$winds = $rss->xpath('//yweather:wind/@speed');
$wind_units = $rss->xpath('//yweather:units/@speed');
$wind = ltrim(rtrim($windd[0])) . "° ".  ltrim(rtrim($winds[0])) . $wind_units[0];

// finally build our output string

echo "local WX: Temp=". $temp . " Pressure=" . $pressure . " Wind=" . $wind . " Condx=" . $condx . "\n"  ;

// --- thats all folks! ---


// functions live here

function get_xml(){ 
 // a really simple file_get file_put routine to grab a copy of the weather XML
 // and save it local to save hitting yahoo every time time we run the srcipt
 global $file, $pageurl;
 $xml =file_get_contents($pageurl);
 file_put_contents($file, $xml);
}

?>

gMFSK enhancements:: WX report... and beyond

2009-12-27T21:00:00.019Z

Hi All...

Its been a while since I last blogged, but feeling suitably pleased with my recent efforts, so its time to blog :)

A while back I noticed that some PSK31 contacts have included automatic weather data, data from qrz.com, data from all over the web in fact. I wanted to add similar functionality to gMFSK

I noted that gMFSK (others will probably work too!) allows a shell command to be run as part of the macro system assigned to the function keys - extending the usual $mycall $yourcall syntax as far as you care to imagine. This is the way in :)

Basically to run any other command in gMFSK the syntax is $(/path/to/the/app)

So... after a bit of digging I found that the yahoo weather xml call brings back the data Im looking for (temp, pressure, wind and a description) and although it uses some extended xml namespace synatx is very easy to parse. I quickly wrote some test apps in php (yes I could have written them in C, perl or any other lang, but php makes this type of rss scraping easy and its what Im most fulent in).

(The reason for deciding upon yahoo by the way is that they change their XML far less frequently than other well known RSS feeds)

Basically the test scripts drag back the rss page from

http://weather.yahooapis.com/forecastrss?p=UKXX1012&u=c

which is my local weather station. To find the url for yours visit http://weather.yahoo.com/ type in your location into the city or zipcode box, and then click on the orange RSS feed button on the right and note the url of the rss feed. The important bit is the p=XXXXXXXXXX bit. You may want to change the final u=f to u=c if you want mainly metric results.

If you view the source of what comes back you will seethat most of the required info is there for the taking, if you can manipulate the

<yweather:wind chill="1" direction="260" speed="14.48" />

colon extended namespace format.

I wrote 4 test scripts for temp, pressure, wind, and conditions using php (If you dont have php-cli installed you need to add it - debian / ubuntu / similar systems can simply run
> sudo apt-get-install php5-cli

to add php script support without the need to add all the apache libs etc)

Each script calls the web page direct, but this is of course wasteful as the data is only updated every 30 mins or so. Most users will want to modify the scripts to point at a local version of the data and cron an hourly download, but thats up to you to work out ;)


temp::
#!/usr/bin/php
<?
$rss =  simplexml_load_file('http://weather.yahooapis.com/forecastrss?p=UKXX1012&u=c');
$temps = $rss->xpath('//yweather:condition/@temp');
$units = $rss->xpath('//yweather:units/@temperature');
$temp = ltrim(rtrim($temps[0])) ."°". $units[0];
echo "T: " .$temp;
?>


Pressure::
#!/usr/bin/php
<?
$rss =  simplexml_load_file('http://weather.yahooapis.com/forecastrss?p=UKXX1012&u=c');
$pressures = $rss->xpath('//yweather:atmosphere/@pressure');
$units = $rss->xpath('//yweather:units/@pressure');
$pressure = ltrim(rtrim($pressures[0])) . $units[0];
echo "P: ". $pressure;
?>

Wind::
#!/usr/bin/php
<?
$rss =  simplexml_load_file('http://weather.yahooapis.com/forecastrss?p=UKXX1012&u=c');
$windd = $rss->xpath('//yweather:wind/@direction');
$winds = $rss->xpath('//yweather:wind/@speed');
$units = $rss->xpath('//yweather:units/@speed');
$wind = ltrim(rtrim($windd[0])) . "° ".  ltrim(rtrim($winds[0])) . $units[0];
echo "W: " .$wind;
?>

condx::
#!/usr/bin/php
<?
$rss =  simplexml_load_file('http://weather.yahooapis.com/forecastrss?p=UKXX1012&u=c');
$condx = $rss->xpath('//yweather:condition/@text');
$condx = ltrim(rtrim($condx[0])) ." ";
echo $condx;
?>

You need to mod each of the scripts to be executable via chmod +x and save to the gMFSK dir in your homedir.

Each script can be tested on the command line.

Finally you need to add them to gMFSK. In my case Ive added a combined wx macro to F12:

WX: $(/home/chrisw/gMFSK/condx) - $(/home/chrisw/gMFSK/temp) $(/home/chrisw/gMFSK/wind) $(/home/chrisw/gMFSK/pressure)

(change chrisw to whatever your homedir is!)

Hitting F12 now of course brings back to the TX window:
WX: Mostly Cloudy - T: 4°C W: 290° 8.05km/h P: 982.05mb

As commented, each script hits yahoo for about 1k of data so while this inst a huge amount, its not very sporting every QSO so consider using a wget script from the cron to grab a local offline copy of the page and parse that rather than hitting the web every time!

Hopefully that provides some inspiration for others to go on to explore other dynamic data includes in gMFSK from not only yahoo weather, but the whole of the net :)

after the dweenotalk..

2009-03-26T23:57:00.001Z

Im just having a cup of tea before bed,so a few moments to reflect on the talk I delivered tonight - an intro to Arduino.

Its a big subject arduino, hard to cover in a short talk. Intros always tend to just scratch the surface, and in-depth talks tends to lose people on the bottom end of the learning curve too quickly. I tried my best to pitch tonights talk somewhere between those extremes, but I wonder if something got lost, or at least watered down in the process. You cant be all things to all people all at once.

My delivery wasnt very polished either, mainly because I just had to throw the material together at a run. Some stuff could have had less detail, other stuff needed more. Its always hard to gauge this till you have run through it a few times.

Oh well... It will be better next time. On the whole though I think tonight was a useful talk for most people. feedback was good. Im pretty sure most people learned at least what arduino is, and what it "could" do for them if they start on the learning project - which of course was the purpose of the evening. I think I got over the enormous flexibility and power of the platform, and also the relative ease of getting onto the ladder - something that other platforms cant compete with. I think the main selling point for most people was when the notion clicked home that you can take a few other bits of hardware and quickly glue them together with a few lines of code and pow! you have a remote ATU,or an antenna analyser, or even just a device that flashes a few LEDs

Time will tell. Success will be measured in how many people actually take onboard the project and experiment :)

Dweeno talk tonight!

2009-03-26T08:40:00.003Z

Tonight Im giving my Talk on Arduinos and introducing the club Arduino project, so I had planned a day in the office to finish off the powerpoint presentation and sort out the arduino sketches for tonight. But... so far its not been quite the start to the day I had expected.

First call of the day has been a trip up to the repeater to re-set the logic... again... so now its 10:07. Ive got a brief bit of work to do mid day too. So a chunk of the day has gone already. No time for blogging really, but I am updating a couple of other info and security sites and blogs, so a quick diversion via here wont really hurt much. Then I really MUST get on with stuff, or there wont be a Talk tonight!

Anyway, my main reason for stopping by is to add a quick post pointing to my new storytlr site - http://chrisjw.storytlr.com which has replaced my old swurl space. Its another stream aggregation system pulling some of my assorted public feeds into one spot. There probably wont be a huge amount of stuff of extra interest there - basically it currently has this feed, twitter status, tumblr pix uploads and blog, my other chrisjw - random thoughts blog (life linux and other geekishness) plus pictyre feeds from picasa and flickr. Oh... and possibly of a little more interest my public bookmarks from delicious. Hopefully storytlr will be a longer lasting replacement for swurl.

I will add a posting later with links to the arduino talk info.

and the other reason for little dweenofurkling is...

2009-02-12T23:31:00.002Z

and the other reason for little dweenofurkling is... Im just so damn busy with work. Ive still not caught up with all the work I missed over the Christmas break while I was recovering from surgery, and three of my main clients all want me to be doing some fairly major updates right now.

That said, I have found time to start experimenting with the I2C phase of the arduino +DDS project. Basically by the time you have got the DDS60 board and a jog shuttle dial onto the arduino, you are running low on IO pins - the answer is I2C. (yes pix when I get chance!)

Ive used the BV4218 board from ByVac to add a 4x16 char LCD and a keyboard using just two lines from the analog port using the 2 wire lib. Its a great way of saving around a dozen pins. (its well worth a look around the other I2C products from ByVac too)

Im also pleased to report that the Arduino DDS project won first place in the construction competition at Salop Amateur Radio Society tonight too - despite being only proof-of-concept level boards up against some quite stiff competition. (photos will follow)

Too late for more comprehensive updates right now, I will make up for the lack of recent blogging over the next few days once sanity returns to working hours...

UNR - the reason for little dweenofurkling as of late

2009-01-18T12:51:00.003Z

Most of my time over the last few weeks has been taken up with catching up with work and also installing Ubuntu UNR - the netbook remix onto my Acer AA1 and Lyns EeePC701 - so other projects have taken a bit of a background place.

Ive added the arduino IDE onto my AA1 - what an amazing dev tool it makes - ultra portable dweenofurkling!

Full details on one of my other blogs :

http://chrisjw.blogspot.com/2009/01/eeebuntu-unr-on-basic-asus-701.html
http://chrisjw.blogspot.com/2009/01/rip-linpus.html
http://chrisjw.blogspot.com/2009/01/some-unr-screenshots.html
http://chrisjw.blogspot.com/2009/01/more-screenshots.html

DDS60

2009-01-18T12:45:00.002Z

Just a quick update - I finished building another DDS60 board last night and am now designing a new proto-shield that will accept the DDS60 and will incorporate the jog/shuttle design and also an LCD - essentially a complete 0-60MHz VFO system with direct frequency readout.

Full details will follow.

Jogging and shuttling with Arduino.

2008-12-21T11:15:00.030Z

As those who follow my dweenofurkling antics will be aware, Ive recently started experimenting with DDS VFOs (Direct Digital Synthesis Variable Frequency Oscillators) Ive been looking at the AD9851 from analog devices.

One of the easiest ways of building and experimenting with this device is via the DDS60 board from AmQRP This simple board just needs power and a serial data source. Unsurprisingly I plan on using an arduino to provide the correct data-word corresponding to the required output freq. A lot of the groundwork has already been tackled by others - Marxy has a good writeup on his blog which has formed the basis of quite a bit of my experiments to date. My contribution to the cause is towards practical real-world use of the DDS system.

The DDS itself has a frequency range of 0-60Mhz, in 1Hz steps. With such a wide range what would be really handy is the ability to scroll thru a wide range of frequencies rapidly, slow down, then fine tune over a few hertz. A combination of Keypads, up down buttons and rotary encoders are the usual method of changing frequency, combined with an LCD frequency readout. All work fine, but are really rather clunky methods of navigating up and down a wide range of frequencies, but with good fine tuning accuracy.

There is however a device that make this sort of thing really quite intuitive - the Jog/Shuttle Dial

The jog/shuttle dial has an outer ring which allows you to rapidly select +/- movement (usually of position within multi-media) with center stop. The greater the deflection, the higher the rate of change. The inner wheel with finger hole spinner allows fine tuning up down depending on direction of rotation like a conventional rotary encoder.

This type of control features occasionally on high-end radio transceivers for VFO control, but is usually well beyond the means of the typical home constructor. Partly because of cost, and partly because of the complexity of interfacing. HOWEVER!! these days that doesn’t have to be the case :)

The following few blog entries describe my tests interfacing a jog/shuttle control to an arduino for use with the DDS board. Hopefully others will find the tests useful and will incorporate this useful control type into other radio and electronic projects.

So, first things first - where do you get a jog/shuttle control?

Well. You can of course buy one, ALPS make them. Several suppliers stock them. The usual problems of minimum order quantity and cost are however factors to consider here - they are expensive items. There is however a fairly reliable source of jog/shuttle dials available second hand - as long as you dont mind a bit of disassembly to get at them. I refer of course to their use in video recorders. Quite a range of "pro-sumer" grade VCRs sold over the last 10 years will have featured a jog-shuttle dial. Ebay, junk stores and swapmeets etc are a good source.

Another place you may find a jog shuttle dial is on the remote control that went with the VCR - which is where I got the one Im experimenting with. (There are a couple of sellers on Ebay who sell just remotes - and the one I bought cost me about £12).

The case on this one had the usual single screw and snap fit casing lugs, so it was on the bench and plugged into the logic analyser within a few minutes of it arriving in the post.

Bench testing the control

I connected up the remote to a 3v supply via the battery terminals and tacked on some breakout leads to the switch connections to connect up my logic analyser.

The pinout was thoughtfully printed on the reverse of the PCB. I expected to find a simple two-pin-plus- ground AB quadrature system for the jog dial (as denoted by J1/J2, with 0v via C2) and 4 other pins plus 0v common C1 giving a grey coded binary output from the shuttle ring, and this seemed to be confirmed by the pins.

Each pin is pulled high via a 5k res and gives conventional high/low output
.

Firstly I decided to check that the jog dial was as expected - plain old 2bit greycoded quadrature.

Yup, fairly conclusive. I did however note that sometimes the jog dial would produce two transitions per click on the dial, and sometimes only one.

There doesnt seem to be any specific pattern I can find to this, it does just seem to be that the detents are just in unfortunate places. The mark and space ratio was also rather variable, especially when spinning at speed. So far, so good.... So what about the shuttle dial? Slowly rotating the shuttle dial gave the expected single bit change at about 10 degree steps. Building a truth table took just a few moments.
(God knows how I used to do stuff like this before I had a logic analyser - perhaps I had more patience then!)

As expected, only a single bit changes for each step, all the clockwise positions resulting in an odd number, all the anti-clockwise positions resulting in an even number. Not too difficult to match up to either an array based lookup or some bitmath.

So, now its time to warm up the soldering iron again and make up a test rig :)

I carefully removed the control and placed it on a scrap of veroboard and added some 90degree header pins to make plugging it into a breadboard a bit more easy.

Although I could have used the on-board pullup resistors on the arduino board I opted to add pullups to this board as it could then be used stand-alone with my logic analyser and scope etc too.

Here we see the control in place in the breadboad connected to arduino and laptop.

Software:

As with the hardware tests I decided to start with the jog dial first. Initially I checked that I could actually see the 2bit grey code states change as I spun the dial. Once I had verified I could actually see the states I wrote this small test sketch:


-----------------------------------------

/*
Jog test - 1

(a minimal quadrature type decoder for jog dials)

*/

int clock = 6;             // Define encoder pin A
int data = 7;              // Define encoder pin B
int count = 0;             // pre-init the count to zero
int c = LOW;               // pre-init the state of pin A low
int cLast = LOW;           // and make its last val the same - ie no change
int d = LOW;               // and make the data val low as well

void setup() {
 pinMode (clock,INPUT);  // setup the pins as inputs
 pinMode (data,INPUT);
 Serial.begin (9600);    // and give some serial debugging
}

void loop() {
 c = digitalRead(clock); // read pin A as clock
 d = digitalRead(data);  // read pin B as data

 if (c != cLast) {       // clock pin has changed value... now we can do stuff
   d = c^d;              // work out direction using an XOR
   if ( d ) {
     count--;            // non-zero is Anti-clockwise
   }else{
     count++;            // zero is therefore anti-clockwise
   }
   Serial.print ("Jog:: count:");
   Serial.println(count);
   cLast = c;            // store current clock state for next pass
 }
}

-----------------------------------------

None of that should need much explaining, the comments cover pretty much how it works. In an ideal world I would have the polling replaced by interrupts, but as a test for now it seems fine.

As can be seen from the screendump, it was fairly easy to make a running count which was increased and decreased by spinning the jog dial.

Next I wrote a small sketch to work with the shuttle ring.


-----------------------------------------
/*
* Shuttle test prog -1
*/


// define grey code positions stored in 0-15 array in global scope
int  gray2pos[] = { -60,+50,-70,+60,-50,+40,-80,+70,-30,+20,-20,+10,-40,+30,-10,0 };


void setup()           
{
Serial.begin(9600);          // set up Serial library at 9600 bps
pinMode(8, INPUT);           // sets the digital pins as input
pinMode(9, INPUT);  
pinMode(10, INPUT); 
pinMode(11, INPUT); 
}


void loop()                 
{
Serial.print("Shuttle :: Bin:");
Serial.print(PINB,BIN);      // scan PORTB (pins 8-13) and print as a binary
Serial.print(" Dec:");
Serial.print(PINB,DEC);    // print the same data as a decimal
Serial.print(" Pos:");
Serial.print(gray2pos[PINB]);
Serial.println(176, BYTE);  // extended ascii val to get the degrees symbol
delay(1000);
}

-----------------------------------------

This bit might need a little more explaining. As you can see from the sketch, I included an array at the top which held the 16 possible positions the shuttle ring could be in with its correct angle in the array position which correcponded with the decimal value of the 4 data bits from the switch - ie if the switch binary pattern was 0110 th at gives us a decimal value of 6 - so look in array position 6 and we find the value "-80" which indicates the switch was turned 80 degrees anti-clockwise.

The other bit thats possibly not clear right away is where I get this number from... well the easiest way to do quick bit bashing on an arduino is to read all the pins you want as a single port - ie to read each of the bits as its binary equiv. This is done using the PINB command. the B port is actually digital pins 8-13 but I am only using 8-11

So, now lets put both of those together


-----------------------------------------
/*
* Full Jog/Shuttle test prog
*/

                        // global scope vars
int clock = 6;            // Define jog pin A
int data = 7;             // Define jog pin B
int c = LOW;              // pre-init the state of pin A low
int cLast = LOW;          // and make its last val the same - ie no change
int d = LOW;              // and make the data val low as well
int count = 0;            // pre-init the count to zero
                      
                        // define counter shuttle steps array
int  gray2pos[] = { -64,32,-128,+64,-32,16,-256,+128,-8,4,-4,2,-16,8,-2,0 };


void setup()           
{
Serial.begin(9600);     // set up Serial library at 9600 bps
pinMode (clock,INPUT);  // setup the jog pins as inputs
pinMode (data,INPUT);
pinMode (8, INPUT);     // sets the shuttle pins as input
pinMode (9, INPUT);  
pinMode (10, INPUT); 
pinMode (11, INPUT); 
}


void loop()                 
{
checkjog();              // move each of the checks out to a function
checkshuttle();

Serial.print("Jog/Shuttle:");
Serial.println(count);
}


int checkjog(){
 c = digitalRead(clock); // read pin A as clock
 d = digitalRead(data);  // read pin B as data
 if (c != cLast) {       // clock pin has changed value... now we can do stuff
   d = c^d;              // work out direction using an XOR
   if ( d ) {
     count--;            // non-zero is Anti-clockwise
   }else{
     count++;            // zero is therefore anti-clockwise
   }
   cLast = c;            // store current clock state for next pass
 }
}

int checkshuttle(){
count += gray2pos[PINB];
}

-----------------------------------------

and we end up with

And thats pretty much it really. Rotating the shuttle ring further produces a step size that gets progressively larger positive or negative. spinning the jog dial allows fairly precise setting of any value. As the detent clicks on this dial tend to be in odd places, Im tempted to modifiy the code so that it takes several clicks, possibly even a complete turn to increment the count by one. (simple adding of a fractional value and INTing the value could accomplish this).

As high speed isnt expected, its quite OK to use routines like the above, though use of interrupts will of course be a better option.

Its now a fairly simple matter to add this functionality to the exisiting DDS word gen code from the Marxy blog - though Ive just not had chance to start on this yet. Future challenges will however be ensuring that there are enough pins to drive an LCD display for output and the DDS serial stream.

More to follow when I get some more bench time...

Housekeeping...

2008-12-21T10:50:00.002Z

Regular watchers of my assorted blogs will have noticed Ive had a bit of a tidy up. As my assorted blogs have covered travel, climbing, mountain biking, running, electronics and radio, astronomy, photography, family, and life in general some of the blogs have got a little dis-jointed and may not have been of interest to everyone all of the time. So it got to be time for a tidy up. Some stuff has been moved, some stuff that didnt have an obvious home has been removed. Hopefully the revised structuring will make a little more sense and will (hopefully!) be easier to stick to.

The G7NBP - Random noise blog continues to focus on experiments in radio and electronics, but now also encompasses some of my Arduino based experiments too, as they generally have relevance to more general radio and electronics hobby areas.

Other blogs and assoreted life streams are of course still being aggregated at my swurl site - http://chrisw.swurl.com/