I have designed and laid out 2 revisions of a BotBoard using the HC08 and I use these boards on most of my robots. I will share the PCB plans and schematics here for those boards. I also have links to sources for other info, software, designs, etc.

Features of my HC08 Botboard: I use these boards on my bots, so there are common functions that I need these to perform:

• Servo motor driver
• A/D sensor input
• Digital switch input
• LED output on the board for ease of design/wiring
• Multiple input options on port A
• In circuit programming and debugging capability

Notice the groupings of header pins. For instance, the headers on the right side of the board are connected to Port B which can be either Digital I/O or configured as an A/D input on up to all 8 pins. When I use them as digital I/Os I generally have the switch pulled up or down so it is handy to have a connection to power or ground close. Same goes for A/D function. So I placed a row for access directly to the Port B pins with a 5V and ground connection pin at each end. Thus the row closest to the chip is a 10 pin header and then at 0.1" spacing to the right of that are power and ground pins for convenience. I did this same thing for Port D (headers at bottom of board) and A (top of board). For Port A I also put in a 16 pin socket with one side of the socket connected to the pins of port A and the other side all tied to one node. I then put a jumper header at either end that allows me to select if I want that node tied to ground or to power. In the photo above I have put in a DIP switch as a quick input device on the board.

I always wanted a simple output interface on the board for quick development purposes. So on this rev I put in 5 LEDs on port C. These are all surface mounts with 200 ohm SM resistors, just to the right of the CPU.

For power supply I use a 5V LDO regulator, with a Schotky (1N5819) diode in series as a reverse plug protection measure. Just below the regulator are two 2 pin headers where I can jack in for regulated 5 power.

For servo control, I use Port D (headers at bottom). I can plug a servo directly into these headers having it set up in a standard servo connector pinout. I can use the 5V regulated power, but for safety to protect my micro's power supply I also have a header for bringing in external power and I use a jumper to select which.

Programming and debugging the board is easy using the black shrouded header in the top left. I have my MON08 debug interface (RS232 level shifting and configuration circuitry) separate from the board to conserve on space (I save having to put on a DB9 connector and a MAX232 chip with supporting caps this way). I have two of these programming interface boards built and they are easily portable.