This is a demonstration prototype for CircuitPython "coproc" on esp32s2/s3

Coproc is a new feature in CircuitPython 8 for using the riscv "ultra low power" coprocessor on esp32s2 and esp32s3 microcontrollers.

Two difficulties presented themselves to me so far:

• Building a program
• Accessing program variables from Python without manually transcribing hex addresses

The code here builds towards addressing these problems.

Building

.../esp-idf/install.sh
. .../esp-idf/export.sh
make

This builds a.out-stripped, which contains enough information for minidump.

Running Minidump

$ py/minidump.py 
@0000: Load 2906 bytes starting at 4096
shared_mem @ 0x0b7c 0x0400 bytes

This shows the amount of code (& initialized data) to be loaded from a.out-stripped, and at what offset within a.out-stripped that data comes.

Then, it shows the size and offset in ULP memory of the symbol shared_mem.

Using

The demo is designed for the ESP32-S3-EYE board, which has an LED on GPIO3. You can potentially use a different LED location by editing ulp.c and changing the line #define GPIO (GPIO_NUM_3).

After you make, copy a.out-stripped and all the Python files in py to CIRCUITPY. At the repl, import do_coproc. (by not saving this file as code.py, it is not automatically run at startup, which helps when dealing with hardfaults)

The LED will blink at two alternating rates, "around 5Hz" and "around 2.5Hz".

Note that as of 8.0.0-beta.3-31-gedce717cfc, hitting ctrl-c to interrupt the program & halt the coproc frequently causes the device to freeze, disconnect, or restart in safe mode.