MicroPython Challenge for BlackIce

[Folknology]

Challenge - porting Micropython to BlackIce-II?

It would be a great option to offer running on the STM32L433, there isn't an existing STM32L433 port in the MP repo but it is really just a case of four files to map the STM32 HAL for our BlackIce hardcore AFAIK.

We will provide a bag of myStorm addon goodies for your BlackIce for the first to get it working, not forgetting the credibility and kudos you will receive..

[jburgess777]

I suspect the biggest challenge will be the 256KB flash size. The micropython pyboard has 1MB of flash and there are special builds for ESP8266 with only 512KB of flash from http://micropython.org/download which have the comment:
Certain features are disabled to get the firmware down to this size.
I imagine it would be a real struggle to get something working in 256KB of flash.

[Folknology]

Good point @jburgess777 but if you look at the FAQ it can be from about 80K upwards for a minimum install, however sacrifices have to be made in terms of library support. interestingly they are talking about ~280K for a configuration with full STHAL support, not sure what that does or does not include?

The MicroPython dashboard shows various flash requirements overtime as more has been added. In Jan 2015 it would have fitted in our 256K, now it appears to be nearer 320K, however I am not sure if there are options for the build that enable it to be whittled down?

[Folknology]

Just looked at a couple of the examples in the repo, here is an extract from a ESPRUINO_PICO board with stm32f401 which only has 256k AFAIK:

#define HAL_MODULE_ENABLED
#define HAL_ADC_MODULE_ENABLED
/* #define HAL_CAN_MODULE_ENABLED */
/* #define HAL_CRC_MODULE_ENABLED */
/* #define HAL_CRYP_MODULE_ENABLED */
/* #define HAL_DAC_MODULE_ENABLED */
/* #define HAL_DCMI_MODULE_ENABLED */
#define HAL_DMA_MODULE_ENABLED
/* #define HAL_DMA2D_MODULE_ENABLED */
/* #define HAL_ETH_MODULE_ENABLED */
#define HAL_FLASH_MODULE_ENABLED
/* #define HAL_NAND_MODULE_ENABLED */
/* #define HAL_NOR_MODULE_ENABLED */
/* #define HAL_PCCARD_MODULE_ENABLED */
/* #define HAL_SRAM_MODULE_ENABLED */
/* #define HAL_SDRAM_MODULE_ENABLED */
/* #define HAL_HASH_MODULE_ENABLED */
#define HAL_GPIO_MODULE_ENABLED
#define HAL_I2C_MODULE_ENABLED
/* #define HAL_I2S_MODULE_ENABLED */
/* #define HAL_IWDG_MODULE_ENABLED */
/* #define HAL_LTDC_MODULE_ENABLED */
#define HAL_PWR_MODULE_ENABLED
#define HAL_RCC_MODULE_ENABLED
#define HAL_RNG_MODULE_ENABLED
#define HAL_RTC_MODULE_ENABLED
/* #define HAL_SAI_MODULE_ENABLED */
/* #define HAL_SD_MODULE_ENABLED */
#define HAL_SPI_MODULE_ENABLED
#define HAL_TIM_MODULE_ENABLED
#define HAL_UART_MODULE_ENABLED
/* #define HAL_USART_MODULE_ENABLED */
/* #define HAL_IRDA_MODULE_ENABLED */
/* #define HAL_SMARTCARD_MODULE_ENABLED */
/* #define HAL_WWDG_MODULE_ENABLED */
#define HAL_CORTEX_MODULE_ENABLED
#define HAL_PCD_MODULE_ENABLED
/* #define HAL_HCD_MODULE_ENABLED */

I am assuming (maybe incorrectly) that by commenting out parts of the HAL we do not use may result in a smaller binary? There are clearly things we do not support or even need for our implementation of MicroPython, however I am a bit clueless having never used it let alone built it, anyone care to voice an opinion? In addition do we need TCP/IP parts of micropython? those have to take rather a lot of code..

[jburgess777]

I built all the micropython stm32 targets from the git master and the ESPRUINO_PICO was the smallest but even that exceeds 256KB of text:

   text    data     bss     dec     hex filename
 263240      28   44352  307620   4b1a4 build-ESPRUINO_PICO/firmware.elf

Espruino Pico website says the device has 384KB of flash and this matches the stm32f401xd.ld linker script.

Turning off MICROPY_HW_ENABLE_RTC reduces the size to just under 256KB.

In addition do we need TCP/IP parts of micropython?

I think the networking is already disabled in the PICO configuration:

boards/ESPRUINO_PICO/mpconfigboard.h:

#define MICROPY_PY_NETWORK (0)

When I used micropython on other boards they normally appeared on the USB bus as both a serial port (USB-CDC) for accessing the Python REPL and a USB mass storage device for uploading python scripts. Storing the scripts on the device obviously relies on having some unused flash sectors left over so the image would have to be shrunk further for that to work. Would micropython still be useful if it only had the interactive REPL?

[Folknology]

If we could fit in the SDcard support we could put bitfiles and python scripts on that

[Folknology]

When I used micropython on other boards they normally appeared on the USB bus as both a serial port (USB-CDC) for accessing the Python REPL and a USB mass storage device for uploading python scripts. Storing the scripts on the device obviously relies on having some unused flash sectors left over so the image would have to be shrunk further for that to work. Would micropython still be useful if it only had the interactive REPL?

This would still be useful in volatile operations, debugging and interactions with Ice40 etc..

[Folknology]

I just noticed that AdaFruit's CircuitPython (derived from MicroPython) fits on their smaller boards like the Tinker which only have 256KB:

adafruit/circuitpython

Maybe this is an interesting route for exploration..