What is a PICAXE?

PICAXE's are a variety of microprocessor and microcontroller specifically designed for controlling hardware. The Basic STAMP is one example. PICAXE's are great for use in robots and sensor devices.

We are prototyping on Wishboard then use Veroboard (and an 8-pin IC socket) for finished circuits.

Typical starting point; just the PICAXE-08... Holes marked 1,2 and 3 (directly above link wire and below the 10k resistor) are where the programming lead is plugged in when neccessary. Read more about the PICAXE-08 chip and pin configuration here...

 

MIGHTY MOUSE CIRCUIT

We have been using old computer mouse bodies to make dataloggers and decided we as well make them into robots too!

We will use the circuit suggested by the manufacturer (Revolution Education Ltd)...

A pair of transistors turn on the output device when the PICAXE output pin is made HIGH. Motors must have noise supression capacitors fitted (we use a 104 green cap with 1.5-3V DC motors) We will use two output pins from the PICAXE to control two motors.

BEWARE: The transistors have different configurations and you can identify which leg is the base and collector from the pictures below...

 

Wishboard version:

SYMBOLS: MR = Motor (Right) ML = Motor (Left) SR = Sensor (Right) SL = Sensor (Left) c,b,e = collector,base,emitter of BC548 c2,b2,e2 = collector,base,emitter of BC639 The 10k resistors are for: sensors (see voltage divider notes) output to motors (see schematic above)

Mighty Mouse Junior uses Light Dependent Resistors (LDR's) as its 'eyes' to either run away from light or move toward light. You can even get him/her to follow a line drawn on the floor or desk! You can download the Light Follow program or Light Avoid program a try to make more complicated 'behaviours' for your cyber mouse.

Veroboard version:

If you want to transfer to a smaller veroboard circuit, use the blank template below to decide where to place components. You can use the circuit provided as one possibility...

PICAXE pin 1 and 3 are input pins connected to LDR's. One leg of the LDR is pushed into the socket on the appropriate rail (eg, see rail running up from pin 1 on diagram above) and the other is pushed into any of the sockets on the +ve power rail (second rail in from left).

PICAXE pin 2 and 4 are output pins, connected to the appropriate 10k resistor and transistor pair to control a single motor. One lead of a motor is pushed into the socket next to the collector leg of the BC 639 and the other is pushed into any of the sockets on the +ve power rail (second rail in from left).

Power leads from the battery pack: +ve lead is pushed into any of the sockets on the +ve power rail (second rail in from left) and the negative pushed into the bottom socket, first rail on the left.

Programming lead plugs into the row of three sockets between the two yellow link wires at the top of the board (1,2,3).

Optional 'Power On' indicator LED: Long leg is pushed into the socket on the rail running up from pin 0 on diagram above, the short leg is pushed into the top socket on the negative power rail (first rail on the left) - REMOVE LED WHEN PROGRAMMING THE CHIP.

BLANK VEROBOARD TEMPLATE:

The smaller veroboard circuits fit easily into an old computer mouse.

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TRY THESE:-

1. Download the Light Follow program or Light Avoid program a try to make more complicated 'behaviours' for your cyber mouse.
2. Devise a new circuit where a motor can be made to be on-off-reverse from one output pin.
3. Try making a mono-rail train that stops at "stations" for set time periods before carrying on. You might try using LDR's or IR phototransistors to detect black 'STOP' signals marked onto the mono-rail.
4. Make five or six of the cyber mice and see if you can get them to swarm toward light. Can you get them to follow each other around? Can you get them to communicate to each other?
5. You could replace the LDR's with any other sensor you can think of. How about touch sensors (switches)? Heat?
6. Replace the wheels and design walking legs for cyber spiders! Get them to swarm and attack!
7. Ignore the sensors altogether and programme the cyber mice to "dance" or behave in other predetermined ways.
8. Try the PIC-18 for more advanced robots.

Good luck, let us know how you get on...