arduino-coldfire-bdm

An interface to Motorola® Coldfire processors' Background Debug Interface (BDM) using an Arduino.

pip install arduino-coldfire-bdm

What?

A long long time ago (the mid-1990s), Motorola created a series of CPUs derived from the 68k architecture, called the Coldfire. These processors are largely obsolete today, but are still found in certain industrial equipment and embedded devices released around that time; including some vintage synthesizers, like the Alesis A6 Andromeda.

This repository contains two things:

• an Arduino sketch, which allows connecting pretty much any Arduino to a Coldfire processor's Background Debug Mode (BDM) port to send and receive data
• a Python library to connect to an Arduino over USB serial, to allow running high-level debugging commands, like:
  • tracing execution (i.e.: like GDB or LLDB)
  • dumping the contents of memory to a file
  • erasing and re-flashing an attached flash memory chip
  • testing attached RAM chips
  • whatever else you want; it's Python! You can script it.

This library, when paired with an Arduino, performs many of the same functions as PEMicro's Multilink debugging probes. This library is free, runs wherever you can run an Arduino and Python code (rather than just on Windows), and requires no drivers. However, this library is way slower, is missing a ton of functions, and has no IDE support.

Why?

I bought a broken Alesis A6 Andromeda, and wanted to try fixing it by re-flashing its firmware without doing any soldering, because I'm bad at soldering. Read about that journey on my blog.

How?

I read the MCF5307 data sheet (484 pages) very carefully. It documents how to connect to a Coldfire BDM port from first principles.

See the top of arduino-coldfire-bdm.ino to figure out which pins to connect between the Arduino and your Coldfire's debug port.

Can I use this for other things?

Probably. There are certain assumptions made (especially around interfacing with Flash or RAM) that apply only to the Andromeda, and may not be useful for other devices. Pull requests to make this code more generic would be welcomed.

What if I brick my device?

Here's the license; I take no responsibility if this software is misused. You should probably read the software carefully first.

Also; I tested this with a 5V Arduino on a 3.3V Coldfire CPU. It seemed to work just fine. That might fry your device; your mileage may vary.

Copyright (c) 2022 Peter Sobot

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a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
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permit persons to whom the Software is furnished to do so, subject to
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The above copyright notice and this permission notice shall be
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