All the PIGGYAXE motherboard circuits are based on the world-renowned PICAXE family of micro-controllers. Put very simply, its a chip that you can reprogrammed 1,000’s of times to sense and control ‘things’.
The basis of the whole family of projects is the PIGGYAXE motherboards of which there are 3 (08Mx shown above).
PIGGYAXE uses the 08Mx (08M2 preferred), the PIGGYMIDDLE uses the 14M2 and the PIGGYMAX uses the 20M2.
The concept is simple, any motherboard includes all the download components, a battery snap connector with stress relief holes (not needed on 12 volt powered boards), a 1 amp reverse protection diode and a 100uF smoothing capacitor for use with power supplies and when driving servos. At the other end (or sides, dependent on model, see separate pages on 14M2 and 20M2) there is access to all the I/O (0-4) of the 08Mx and +ve (positive) and 0v (negative).
With a built and tested motherboard the daughter boards can be built and either plugged in (using SIL PCB header pins and sockets) or permanently fitted to the motherboard using just header pins. Firstly there are several options in terms of orientation, governed in part by the mounting options needed.
Where possible the daughter-board provides a mounting via either a pre-drilled fixing hole (nut and bolts, or PCB stand-offs) or even the board mounted potentiometer. This may mean that the LED(s) it controls need mounting on wires, but the concept is covered by allowing splitting the RGB pcb. Photos show this later, just browse down. Equally, the board could be mounted by its 1 or 3 LEDs and the input device remote mounted. There is a lot of choice……
The top two photos show (l to r) daughter-board above motherboard and motherboard above daughter-board.
Using 90 degree header pins offers further options, no shortage of choice here…
The first daughter-board is called the RGB multi-board as it was designed to offer the greatest range of options when controlling 3 LEDs. The LEDs can be either separate Red, Green Blue ones of a single RGB common cathode unit – the PCB can accommodate both types, all of which could be the same colour, such as white. Current limiting resistors are provided for on the PCB and should be selected to suit your LEDs and power supply. Some users let the PICAXE chip naturally limit the current (around 30 mA) but this is not good practice for long term reliability.
Lets look first at the many options you can have with just this single daughter-board….keep scrolling down!
All the variations on this page can be built on the single PCB – just select what you want as you design and build.
Firstly, how to fit a single RGB LED to the board – yes it was designed for this (use a common cathode LED).
Next up is 3 LEDs and an LDR (Light Dependant Resistor) – lights could come on in the ‘dark’. A logical extension of this is provided when you add the PIR module shown on the right. Now the lights only come on when its dark AND movement is detected. These PIR modules are available on Ebay (or from Rapid Electronics) and +ve, signal and -ve are provided on the PCB for you to connect them (small link to add).
Next we have a way of mounting a potentiometer to the PCB using some 90 degree header pins or an option to careful ‘tweak’ the potentiometer legs. Be careful how you do this, the potentiometer substrate is not that strong.
Either of these options make it easier to mount the PCB assembly in your product as you use the potentiometer mounting shaft. If the potentiometer is mounted under the board for instance, you can retain the logical progression by a simple tweak in the software.
The PCB then assembles like this, shown here with a single RGB LED and the motherboard underneath. There are a lot of things you can do with this combination. The Picaxe forum ( well worth registering yourself on) yielded some excellent listings that do RGB, Colour Mixes, flickering effects and colour changer (3 channel ‘pwm’ done very cleverly with the pulseout command). Its on the resources page along with everything else.
Yet another option is to use the excellent Dallas DS18B20 temperature sensor which communicates directly with the Picaxe chip, including a temperature range of -25 up to 125 centigrade. That really opens up some options in terms of projects. It still controls up to 3 LEDs, your choice what to do with this, but baby bathwater alarms, frost detectors (gardeners and motorists), central heating economizer indicator, hypothermia alarm, the list goes on.
There remains the option using a simple push-button input which can be used with either a pull-up (configurable in software on 08M2), pull-down (10K) for simple ‘step-through’ programs. Now it gets interesting, as using a simple piezo sounder and a little bit of signal conditioning, a coin-drop or ‘tap’ activated option becomes viable. An early prototype is shown below, along with a pupil built one of 3, or all on, then off desk lamp.
This daughterboard (an early prototype) is shown connected to a ‘tap’ sensor. This is a piezo sounder used in reverse – it you tap it, it produces a waveform. By adding a 5 volt zener across the back of the piezo, the original sine wave of up to 16 volts (depends how hard you tap the sounder!) is clipped to a maximum of 0.7 volts negative and +5 volts positive, ideal for feeding into the unprotected input 3 of the 08Mx. Adding a 1M resistor across the pins ensures that the input pin is held low until triggered.
The sounder can be glued to a variety of materials which, so long as there is a degree of flex, will produce a reliable trigger. I have used 1.6 (16g) aluminum, 3 mm acrylic, 4 mm MDF and 4 mm birch ply. They make ideal ‘coin drop’ sensors which opens up the ‘Design and make a coin operated novelty’. For the 08Mx I use input 3 for digital inputs, input 4 for its A to D convertor, and 0,1 &2 for outputs, sometimes with 4 too (RGB & White although the board is not configured specifically for 4 outputs, it can be used). On that basis, and depending how many times you are prepared to ‘tap’ something, all sort of projects become possible. Shown below is a ‘tap’ controlled RGB & White, built using aluminum sheet, tubing and laser cut acrylic based year 9 light. Power was from a modified phone charger.
Finally, you may wish to remote-mount the LEDs from the motherboard assembly. The following three pictures show how that can be achieved with a cordless drill and some multi-strand wire. I use 7/0.2 in a range of colours. Keep the hank very tight as you run the drill for the neatest results.
First of all twist the wires as shown – 4, generally RGB and an earth return (green or black although any colour will do).
Then strip and assemble as shown above. Don’t forget the single wire link on the daughter-board to provide the earth return for the potentiometer. This runs around the periphery of the uncut PCB so only needs adding if you separate the two halves of the board.