c8aprog, a Programmer for the MC68HC705C8A and MC68HSC705C8A

I was inspired to build this board and write the programmes when I discovered the cost of having my M68ICS05KJ repaired. I damaged the MC68HSC705C8A on the board by inadvertently connecting the programming voltage to an I/O pin. All I needed was a programmed C8A as described in the Operator's Manual of the M68ICS05KJ but it seems that they're not available. The offer from Motorola's official dealer was to have the whole board replaced for a tidy sum. A blank C8A cost me $9 and I designed this MC68HC705C8A programmer to programme it.  The circuit is similar to the MC68HC05PGMR board described in the MC68HC705C8A.pdf manual on Motorola's web site. I used parts I had already in my electronics stock; if I had had to buy the parts, I'd have used a MAX233 instead of the MAX232 which requires four external capacitors. I supply the 15v programming voltage from an external power supply so there is no generator on this board.

The two pin header just above the red LED cuts the programming voltage off the pin unless there's a connector on it. This is useful for testing without accidentally setting the security bit thus making the C8A useless. The three pin header right of the MAX232 is the RS232C connector which connects to the serial port of a computer running gnu/linux. The voltage required on the IRQ pin to put the C8A into bootloader mode is derived from the 15v voltage using a two resistor potential divider. The third picture is my hand drawn diagram. I have left it in colour rather than grey scale so that the blue lines are not confused with connections. The wiring of the MAX232 isn't shown.

Here is a gzipped tarball (30k) of all of the version 1.2 source code, executables for gnu/linux and documentation. The only change I made in going from 1.1 to 1.2 is the README. I forgot to update the file descriptions in that file on going from 1.0 to 1.1. The software is compatible with the MC68HC05PGMR board and this might be useful for people who do not have any way to programme a 2764 required by the board. The tarball doesn't contain this web page or the images since they would add considerably to the size of the file.

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Click on an image to view the fullsize image.

Ian
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