It is an assembler toolchain for the ESP32 ULP (Ultra Low-Power) Co-Processor, written in MicroPython.
It is able to translate small, simple assembler language programs to a loadable/executable machine code binary, at runtime, on the ESP32 microcontroller, from projects implemented in MicroPython.
This is intended as an alternative approach to assembling such programs on a development machine using the binutils-esp32ulp toolchain from Espressif.
The most commonly used stuff should work. Many ULP code examples found on the web will work unmodified. Notably, assembler macros and #include processing are not supported.
Expressions in assembly source code are supported and get evaluated during
assembling. Only expressions evaluating to a single integer are supported.
Constants defined with .set are supported in expressions.
We have some unit tests and also compatibility tests that compare the output whether it is identical with binutils-esp32ulp output.
There is a simple preprocessor that understands just enough to allow assembling ULP source files containing convenience macros such as WRITE_RTC_REG. The preprocessor and how to use it is documented here: Preprocessor support.
The minimum supported version of MicroPython is v1.12. py-esp32-ulp has been tested with MicroPython v1.12 and v1.17. It has been tested on real ESP32 devices with the chip type ESP32D0WDQ6 (revision 1) without SPIRAM. It has also been tested on the Unix port.
There might be some stuff missing, some bugs and other symptoms of beta software. Also, error and exception handling is rather rough yet.
Please be patient or contribute missing parts or fixes.
See the issue tracker for known bugs and todo items.
We are NOT (fully) compatible with "as", but we try to be close for the stuff that is actually implemented:
https://sourceware.org/binutils/docs/as/index.html
Espressif docs:
https://esp-idf.readthedocs.io/en/latest/api-guides/ulp_instruction_set.html
https://www.espressif.com/sites/default/files/documentation/esp32_technical_reference_manual_en.pdf
Espressif ULP examples:
https://github.com/espressif/esp-iot-solution/tree/master/examples/ulp_examples