Tuesday, July 31, 2007

Picaxe breadboard adapter

A quick project to simplify Picaxe prototyping on my breadboard. The idea is to house the Picaxe chip (either an 08M or 14M) and "standard" serial interfacing circuit on a "breakout" board that can be easily plugged into the breadboard while providing easy access to the chip's pins.

  1. power input, about 5V, will be regulated by LM7805
  2. 3.5mm stereo serial socket
  3. serial mode selector, switches serial in between "pin 5" (program mode) and "pin 3" (control mode)
  4. power switch
  5. jumpers to allow isolating standard serial circuit to "override" via breadboard
  6. 14 pin socket
  7. header pins to provide 5V and 0V to "power rails" of breadboard
  8. header pins to connect Picaxe to breadboard

serial schematic

power schematic

For some unknown reason, I had to add an extra 10k resistor between leg 2 and ground (soldered on the underside of the pcb, not shown on schematic.)

The board works pretty much as I'd hoped. Unfortunately it is quite difficult to insert/remove from the breadboard so a future version would only have a single row of header pins. Another addition would be a DC socket to allow powering from a "wall wart" and I'd improve the layout a little to allow easier access to the switches.

1 comment:

Andrew said...

e 10K resistor is to pull down the serial input pin. It is normally used for programming.