Pico adapter

pico-puller

A Raspberry Pi Pico-based project for reading and programming the flash memory of Renesas M16C/62A processors.

The M16C Processor

The Renesas M16C/62A processors are a 16-bit microcomputer family with 1M address space and multiple packaging and memory options. It is often used in embedded systems.

The Raspberry Pi Pico

The Raspberry Pi Pico is a small, inexpensive single-board microcontroller with dual ARM M0 cores and a number of other interesting features, including USB support.

This project

This project is intended to allow a programmer to connect the Raspberry Pi Pico to a circuit containing a Renesas M16C/62A processor and extract the flash memory contents whether the ROM code protect function has locked the firmware or not.

How to use it

Step 1: Physical connections

Full details on how to build the project and use it are in the manual.

The short version is this. First, make the following ten connections between the Pico and the circuit with the M16C processor. M16C pin numbers refer to square package/rectangular package.

Step 2: Configure CMake for build

There are only two required configuration items to define. The first is to define a PICO_MOUNT_LOCATION. This is the directory in which your Raspberry Pi Pico appears when first plugged in as an unprogrammed part. On a Fedora Linux distribution this is /run/media/username where username is whatever name you use to log in.

The second is PICO_SDK_PATH which should point to wherever you've installed and built the pico-sdk.

Optional but recommended are to build the documentation for this program (WITH_DOC) and whether to build a Release or Debug version. A sample command line for this, if you are in pico-puller subdirectory is this:

cmake -DPICO_SDK_PATH=~/tools/pico/pico-sdk -DPICO_MOUNT_LOCATION=/run/media/beroset -DWITH_DOC=ON -DCMAKE_BUILD_TYPE=Release -S . -B build

This will create and configure the build subdirectory.

Step 3: Build the software for the Pico

If the configuration described above has been done, building the software is very simple:

cmake --build build

Step 4: Install the software

Once the software is built, copy the pico-puller.uf2 program to the Pico. This can be done automatically using sudo cmake --build build -t install. That will also automatically install the pico-puller script on your machine.

Step 5: Use the software

If everything was installed, using the software is very simple. If you want to get a dump of the contents of the user flash, use this:

pico-puller dump

You can redirect this to a file for further analysis:

pico-puller dump > foo.hex

If you wish to covert that to a binary file, one simple way to do it is to use a combination of awk to remove all lines that don't start with a hex address and then feed the result to xxd.

awk '/^[0-9a-f]{8}:/' foo.hex |xxd -r -g -1 > foo.bin

Or if you only want the binary file, that can be done all in a single line:

pico-puller dump | awk '/^[0-9a-f]{8}:/'  |xxd -r -g -1 > foo.bin