JOY-2-PIC ICSP PIC Programmer for your Atari
Ever wish that your A8 could transform into a programming tool for those Microchip PIC MCU's that everyone's using for embedded projects now days? Well even if this never crossed your mind, it did for a couple of guys on AtariAge, thus setting off on a journey that resulted in the JOY2PIC Programmer.
So how exactly does this work? Through the use of a voltage tripler, one of the joystick's 4 I/O lines is translated into what a PIC chip needs to initiate In Circuit Serial Programming. The other 3 bits of I/O are then used to communicate with the PIC, and through the use of a custom A8 software program, re-flash the program memory space with your choice of firmware (more info on PIC ICSP).
Using the Programming Software
Program Author Notes
From the bwdos prompt, type:
READHEX SAMPLE.HEX SAMPLE.COM
Now, you see a prompt with the available PIC models. Select the one you want by entering the number and RETURN.
This takes a while, reading "SAMPLE.HEX", and producing "SAMPLE.COM". If you omit the output name in the command line, the default is the same as input with ".COM" instead of any existing extension. If you omit both parameters, the program asks for the input HEX file name.
After the end, press RETURN to return to DOS.
Now, you have in the disk a new binary, run it to program the PIC.
Now, pressing START begins the programming. The background color flashes to indicate progress.
The programming is a little slow, because I have limited the speed to one WSYNC per clock transition, this is about 7.7kbaud, and the programming protocol takes 28 bits for each word plus 3 ms of "programming time", so 2kword of PIC memory should take about 15 seconds.
- Daniel Serpell
This project was a joint effort by Daniel Serpell (dmsc) and myself, that began in December of 2015. The main thrust being to provide an inexpensive and easy to use method for the DIY person to update the firmware in the TK-II boards that were under development. It has since been put to use for a few other projects, and likely will find itself useful for even more to come.