Been busy at work with an ‘Inspection’ which as far as I can tel went well, then I got on with something educational…..
The binary timer software was checked against a clock and 8 thousandths of a second were added to the time-trimming loop, so my rough guess about processing time was not far out! I have not investigated the effects of temperature on the internal RC oscillator, but I’m sure either the Picaxe or Microchip datasheets for the 14M2 will tell you. Its not an atomic clock timer so it does not really matter – as-is its fit for purpose. I have also wired up some amazing little 3-axis G sensor boards, selectable 1.5 G or 6 G, plus a free-fall output. (eBay for about £1.50 delivered!) and written a few lines to control three servos. They all waggle as expected, i.e. up-down, left-right and forwards-backwards. At the moment its just a novelty box to interact with (pupils love it) but I had an application idea when reading an article about building a satellite tracking beam aerial. I have not checked to see if its linear yet but it would make a useful 180 degree potentiometer if you had something that needed that….like the horizon to horizon azimuth (via the pole star!) controller. Although suitable geared motors exist in abundance, coupling a potentiometer to provide positional feedback is always a bit of a nightmare. For a heading controller I seem to remember that Rapid Electronics (and quite probably by now eBay) sell ‘electronic compass’ modules that could deal with that problem too. A lot easier than gearing a 300 degree potentiometer to represent 360 degrees.
Although on paper a PIGGYMIDDLE 14M2 has enough A2D inputs (we needed 5), doing so uses up some of port B, which, it turns out, is the only port that can support servo outputs. So we reached for a PIGGYMAX (20M2 based) which was able to deliver what we needed. The result can be seen on the Piggymax – the porker page in the form of a glove controlling the 5 servos. Work in progress, but only 17 lines of code to do this and 5 of those were setup! Wonderful.
After using some of these boards as an extension activity (where one designed a case that exposed the circuit board) I put together my own version. Nothing special but it does allow you to use the board AS-IS so very little extra wiring needed – just two wires to the switch. The potentiometer mounts the PCB with a bit of glue to stabilize things at the LED end. The motherboard is permanently joined to the daughter (direct on header pins) so its very compact. Power is from a 3 or 4 flat AA pack that sits underneath. How it works is shown in a video found on the Piggyaxe Advanced Electronic files page http://www.g4xat.co.uk/piggyaxe-what-is-it/piggyaxe-advanced-files/
It started as a germ of an idea, but fits in with my drive to get the most out of the least. So I combined the 3 channel power driver with the 4 channel IR controlled power driver. Although you can’t mount the pot on the board (or use channel 4 as a power driver since you are using it for the A2D) it does mean that one board now does both jobs, just have to hard-wire the pot in – extra hole provided.
On a similar basis I looked at combining the 8 channel power driver with IR receiver capability, whist making some pin allocation changes to give access to all 4 hardware PWM channels. It now lets you build either an IR controlled 8 channels, OR an A2D controlled 8 channels, with two digital inputs to further expand capabilities. The ability to use either pull-up or pull down resistors has been included on the board as port C does not support the internal ones.
To control 8 channels without buying a controller posed a brief problem, until I thought about using a “dial the code and press to send” option. Based on the Piggyaxe 08M motherboard and RGB daughter-board, it was a simple matter to use the A2D to select the number. With 300 degrees of rotation to subdivide, so every 20 degrees would allow 15 different commands to be easily selected. One push-button to send, one IR LED, one Indicator LED, last channel wired as as a push-switch to ground using internal pull-ups which could be used as the ‘write to memory then all off’ button…..should be easy enough to code 🙂
About time, I have started uploading documents and support materials for the circuits detailed here. There is a lot more to come but in the short term, if you need to know something, just email me.
The website update is now well underway, with all the circuits I have available described and photographed. Still to do is the resources page where I hope to have available the circuit diagrams, parts lists and any relevant starting point software that I have written. Some of this (parts lists mainly) still needs to be written, so work in progress.
With the labours of the summer term 2013 over and the dust beginning to settle I am now updating the website with more information and photos of the many and varied solutions this ‘PIGGYAXE’ family offers the builder. A4 PCB panels are available for £32 including UK mainland delivery – that’s 39 pcbs that build into 19 different projects. That’s a lot of projects…
As per the title, after a serious amount of prototyping, development work and a leap of faith I now have some rather handy boards available.
First off is a single A4 panel comprising 39 different boards, building up into 19 different projects with some duplicates of the beginners stuff. Ideal for hobbyists, experimenters, schools etc.
8 different Picaxe 08M based project boards (with 8 motherboards to control them). 4 different 14M2 boards and motherboards, currently a Binary timer, KITT scanner, Dual RGB+2 White and a 8 channel power driver for 12 volt tape LEDs.
Second I have a single 08Mx motherboard / daughter board pair, the daughter board can take 7 (or more) inputs and then control 3 LEDs (Red, Green, Blue or single RGB) using a variety of software. With modern LEDs (also available) you can seriously light a room!
Also available is a lovely little board for the ever useful Joule thief, designed to fit in 1/2 of a dual AA battery box, compete with switch. I have 30 of these KITS available at £2 each, plus delivery based on numbers. This includes 4 LEDs with each kit, so you can choose or change.
Contact me for more info, but the A4 panel is £32.5 delivered UK and the smaller boards (2, one of each, are £1 each plus delivery).
The first batch of these neat pupil-proof PCB are available. Contact me if you want some.
Yesterday 18th December saw 4 participants enjoy a hands-on day building a variety of handy but useful circuits. Next offering will be on 11th January (Friday) when I’ll be covering the PIGGYAXE system.
On the development front I have updated the Joule Thief PCB to take account of difficulties pupils found when assembling them and have also added an option for a tiny switch. Bu using this and reverse-mounting the parts (sort of surface mount, even though you use the holes) you can fix the PCB to the back of a single AA cell holder. Now you can’t make a product much smaller than that! Photos to follow in the Electronics that work section.