MC68302 backup

[splinterx]

Hello everyone,

I have an old I/O PCB with an MC68302 and a 29F010 on it. I've noticed JTAG pins marked on the board. How can I make a backup/restore of the MCU and flash memory? Could someone point me in the right direction? What hardware and software can I use for this? I don't have experience with ColdFire/Motorola MCUs. 

Thank you very much.

[TomE]

Count me very surprised. That chip dates from the very early 1990's (yes, 34 years ago) and it does have a JTAG port. But unlike more modern (only 25 years old Motorola CPUs, the port doesn't look to be usable for debugging. It isn't a combined JTAG/Debug port - it is just JTAG. Download and read the Reference Manual, Chapter 7.

There's no way you're going to find any 34 year old development tools for this chip out there. When I was working on these we used expensive emulators plugged into stacked sockets. We didn't use JTAG and we didn't in-circuit program then. We programmed the Flash chips by unplugging them, putting them in the programmer, then plugging them back into the board. Does this board you have there have the Flash chip in a socket? If so, then remove it and try to find a programmer/reader for it.

Tom

[splinterx]

Thank you, @TomE , for your answer. It's so cool to meet people who have hands-on experience with such things. For the TSOP32 29F010, it's clear that I need to remove it and backup with programmer, but how do I back up the microcode of the PQFP MC68302? Maybe you can remember the name of the programmer for MC68302 or suggest an alternative? Thank you.

[TomE]

The first thing you should do is to download and READ the manual so you know what you're dealing with.

Microcontrollers now almost always have internal Flash and RAM. That lets you build a minimal system consisting of that chip only. That wasn't always the case and also isn't the case now. A lot of CPU chips are made expecting to be used with large amounts of external memory, so they don't have any inside. The 68302 is one of those No internal Flash (but it has about 1k of internal SRAM). Look at the Block Diagram - figure 1-1 in the manual to see this... Except there's a problem. This chip is SO OLD it doesn't look like there's an electronic copy of the manual available. The third issue of the Errata for the manual is dated 1992. If you get the MC68EN302 manual or the MC68QH302 or MC68LC302 you'll have a starting point, but they refer you back to the MC68302 manual for details.

Which you can find at Bitsavers:

https://bitsavers.org/components/motorola/68000/MC68302_Integrated_Multi-Protocol_Processor_Users_Ma...

There are two processors inside the MC68302. There's the 68000 core and the communications processor. The latter has internal ROM-based code, but you can load custom microcode for it.

All the code the MC68302 (and optionally the CP) have to be in the external Flash.

So this has gone from a problem of "custom hardware to read the Flash via this chip" to "far simpler problem of reading and writing general purpose Flash chips".

Just type "flash programmer" into Google and look through the specs to see if any of them can handle the ancient 29F010. Then be very careful as nobody has TESTED programming these for 30 years or more, so they may not work, and may destroy your original memory chip. Read this:

https://www.eevblog.com/forum/repair/any-experiences-here-with-failing-28f010-28f020-flash-memory/

Tom

[Bio_TICFSL]

Good!