micropython on STM32G0B1CC

[patfrench]

Hello,
I need to run micropython on an STM32G0B1CC and I would like to know which files to modify.

micropython STM32G0B1RE exists, I suppose that it should not have much modification.

Thank you

[robert-hh]

The difference between the two devices is flash size and pin count.
CC: 256kB flash, 48 pins
RE: 512kB flash, 64 pins

The lower flash size of the CC part is the major problem. The firmware size is about 300k at the moment. So you have to drop quite a few packages for a fit to get the firmware size below 256k, or below 200k to get a small file on board system.

[patfrench]

Hi @robert-hh
Thanks for your reply.

I have an external flash for memory. Do I have a chance of reaching the minimum required footprint?

I have no files to modify?

Thank you

[robert-hh]

I would have to look into the details of the chip & board, whether the external flash allows XIP. If yes, the loader files have to be adapted. If not, the external flash can at least be used for the file system.
The source code for MicroPython is on Github. To modify that for your board seems quite a task.

[patfrench]

Hello @robert-hh
Thank you for your help. Modifying micropython scares me.
I'm afraid I won't understand what I'm doing. Today I can change one last thing.
I have a second version with an STM32G0B1CE which has 512k memory.

Given my level, it's preferable to switch to this micro

Thank you

[patfrench]

Hi @robert-hh
I modified the port NUCLEO_G0B1RE for my STM32xxxCE I also modified pin.csv

it works at 99%. I think CTRL C doesn't work when my program is launched in RAM (my main.py is empty)

mpremote connect COM30 run test.py

• the program launches
• stuck ! only solution: stop power supply

in REPL mode CTRL C works

mpremote connect COM30 
>>>
>>>

do you have any ideas?

Thanks

[robert-hh]

What is the content of test.py? And by which tool do you connect to your board? If it is Thonny, use something else, try mpremote or Putty.

[patfrench]

In test.py there is

from time import sleep

While True:
    print("test")
    sleep(0.5)

I use mpremote but I have the same problem with thonny

I always have a connection problem with mpremote when I first connect.

On the other hand,
mpremote mip install works.

Then mpremote fs ls works, but as soon as I lose control I have to stop power supply.

Tomorrow I'm going to change my FTDI 3.3V cable

No more USB hub

I don't understand some of the macros in mpconfigboard.h

#define MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE

What's your role? Have I forgotten something in mpconfigboard.h?

Thank you

[robert-hh]

That test loop should be stoppable by Ctrl-C and I do not see a reason why it is not the case.
If your board has USB connected to PA11/PA12, you should be able to use the USB port for REPL.
The Macro MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE enables the flash file system in the internal flash. According to the setting in mpconfigboard.h for the NUCLEO_G0B1RE it is enabled, and you should have a file system.

[patfrench]

here i don't understand

mpconfigboard.h
// HSE is 8MHz, HSI is 16MHz CPU freq set to 64MHz
// Default source for the clock is HSI.
#define MICROPY_HW_CLK_USE_HSI (1)

stm32g0xx_hal_conf.h
// Oscillator values in Hz
#define HSE_VALUE (8000000)
#define LSE_VALUE (32768)

This is the schematics NUCLEO_G0B1RE, there is a XTAL = 32768Hz

is this where my problem is coming from? On my custom board I also have an xtal of 32768Hz

Thank you

[robert-hh]

According to the schematics, the 8 MHz crystal is not present, and the internal clock is used. Since the code runs, the clocks are fine. The problem with ctrl-c is most likely not related to the clock setting.

[patfrench]

Hi @robert-hh

I investigated and here are my observations

This is my test.py

import time
from machine import UART

uart = UART("LP1", 57600)

while True:
    print("test")
    uart.write('abc')
    time.sleep(0.5)

with this code my REPL is stuck, if I remove uart = UART("LP1", 57600) and uart.write('abc') then I can stop the REPL

this is my mpconfigboard.h

// USART1 config
#define MICROPY_HW_UART1_TX         (pin_A9)
#define MICROPY_HW_UART1_RX         (pin_A10)

// USART3 config
#define MICROPY_HW_UART3_TX         (pin_B8)
#define MICROPY_HW_UART3_RX         (pin_B9)

// USART4 config
#define MICROPY_HW_UART4_TX         (pin_A0)
#define MICROPY_HW_UART4_RX         (pin_A1)

// LPUART1 config
#define MICROPY_HW_LPUART1_TX       (pin_B11)
#define MICROPY_HW_LPUART1_RX       (pin_B10)

// USART3 is connected to the virtual com port on the ST-Link
#define MICROPY_HW_UART_REPL        PYB_UART_3
#define MICROPY_HW_UART_REPL_BAUD   115200

if I look in stm32g0b1_af.csv, I wonder if I don't have a conflict between LPUART1 and my REPL on USART3

micropython/ports/stm32/boards/stm32g0b1_af.csv

Lines 27 to 30 in 112f657

	PortB,PB8 ,CEC ,SPI2_SCK/I2S2_CK ,TIM16_CH1 ,FDCAN1_RX ,USART3_TX ,TIM15_BKIN ,I2C1_SCL ,EVENTOUT ,USART6_TX ,TIM4_CH3 , , , , , , ,
	PortB,PB9 ,IR_OUT ,UCPD2_FRSTX ,TIM17_CH1 ,FDCAN1_TX ,USART3_RX ,SPI2_NSS/I2S2_WS ,I2C1_SDA ,EVENTOUT ,USART6_RX ,TIM4_CH4 , , , , , , ,
	PortB,PB10,CEC ,LPUART1_RX ,TIM2_CH3 , ,USART3_TX ,SPI2_SCK/I2S2_CK ,I2C2_SCL ,COMP1_OUT, , , , , , , , ,ADC1_IN11
	PortB,PB11,SPI2_MOSI/I2S2_SD ,LPUART1_TX ,TIM2_CH4 , ,USART3_RX , ,I2C2_SDA ,COMP2_OUT, , , , , , , , ,

And maybe I no longer have access to the REPL (USART3) when I loop on LPUART1

Thank you

[robert-hh]

I cannot tell without digging into the sources, which AFx is used when instantiating an LP UART object. But since you see a problem, you could try to assign LPUART1 to other pins.

[patfrench]

Thank you @robert-hh

my problem is really with LPUART1 but I can't solve it
i'm on

MicroPython v1.25.0-preview.229.g0d46e45a1.dirty on 2025-01-31; NUCLEO-G0B1RE with STM32G0B1xE
Type "help()" for more information.

This code works (UART = 1 or 4)

import time
from machine import UART, Pin

#pb11 = Pin("B11", mode=Pin.ALT, alt=Pin.AF1_LPUART1)
#pb10 = Pin("B10", mode=Pin.ALT, alt=Pin.AF1_LPUART1)

uart = UART(1, 57600)

while True:
    print("test")
    uart.write('abc')
    time.sleep(0.5)

with UART LP1 stuck (with mpremote and thonny)

import time
from machine import UART, Pin

pb11 = Pin("B11", mode=Pin.ALT, alt=Pin.AF1_LPUART1)
pb10 = Pin("B10", mode=Pin.ALT, alt=Pin.AF1_LPUART1)

uart = UART("LP1", 57600)

while True:
    print("test")
    uart.write('abc')
    time.sleep(0.5)

is this how you change the alernative function ?

Thank you

[robert-hh]

The AF function for the UART pins are set when the UART object is created. Setting them beforehand has no effect. Looking into the code it seems that PB10 and PB11 are set to AF1, like it should. So I do not know what happens. How is the result if you define UART3 at PB0 and PB2, or LPUART1 at PC0 and PC1?

[patfrench]

Thank you for your time in helping me

I'm going to start from the beginning because there is something strange.

I upload a firmware (main.py is empty)

• connect with mpremote
• REPL stuck
• power supply OFF ON
• connect with mpremote
• REPL ok
• disconnect REPL
• mpremote fs ls
• mpremote stuck

It's very strange

If I write a program in main.py and I manage to connect with mpremote, I can press CTRL-C but I can't do anything else.
mpremote fs ls = blocked
mpremote reset = blocked
mpremote soft-reset = ok
mpremote fs ls = blocked

[patfrench]

Hi @robert-hh

I confirm that I have a problem if i use LPUART1

I switched the REPL to UART4 and I still have the problem: if i write in main.py

import time
from machine import UART, Pin

uart = UART("LP1", 57600)

pb11 = Pin("PB11", mode=Pin.ALT, alt=Pin.AF1_LPUART1)
pb10 = Pin("PB10", mode=Pin.ALT, alt=Pin.AF1_LPUART1)

time.sleep(2)

while True:
    print("test")
    uart.read(2)
    time.sleep(0.5)

or

import time
from machine import UART, Pin

uart = UART("LP1", 57600)

pa2 = Pin("PA2", mode=Pin.ALT, alt=Pin.AF1_LPUART1)
pa3 = Pin("PA3", mode=Pin.ALT, alt=Pin.AF1_LPUART1)

time.sleep(2)

while True:
    print("test")
    uart.read(2)
    time.sleep(0.5)

or

import time
from machine import UART, Pin

uart = UART(3, 57600)

time.sleep(2)

while True:
    print("test")
    uart.read(2)
    time.sleep(0.5)

i have access to the REPL but i can no longer access the file system.

I have try

>>> import os
>>> os.listdir()
['boot.py', 'main.py']
>>>os.remove("main.py")
>>> os.listdir()
['boot.py']

power supply OFF/ON and

mpremote connect COM63 fs cp test.py :main.py
cp test.py :main.py

mpremote connect COM63                       
Connected to MicroPython at COM63
Use Ctrl-] or Ctrl-x to exit this shell
import main
test
test
test

mpremote connect COM63 fs ls                 
ls :

stuck
power OFF/ON + CTRL-X pycharm

Traceback (most recent call last):
  File "C:\Users\ppetit\AppData\Local\anaconda3\lib\runpy.py", line 196, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "C:\Users\ppetit\AppData\Local\anaconda3\lib\runpy.py", line 86, in _run_code
    exec(code, run_globals)
  File "C:\Users\ppetit\PycharmProjects\micropython_ngt\venv\Scripts\mpremote.exe\__main__.py", line 7, in <module>
  File "C:\Users\ppetit\PycharmProjects\micropython_ngt\venv\lib\site-packages\mpremote\main.py", line 538, in main
    handler_func(state, args)
  File "C:\Users\ppetit\PycharmProjects\micropython_ngt\venv\lib\site-packages\mpremote\commands.py", line 343, in do_filesystem
    for result in state.transport.fs_listdir(path):
  File "C:\Users\ppetit\PycharmProjects\micropython_ngt\venv\lib\site-packages\mpremote\transport.py", line 81, in fs_listdir
    self.exec(cmd, data_consumer=repr_consumer)
  File "C:\Users\ppetit\PycharmProjects\micropython_ngt\venv\lib\site-packages\mpremote\transport_serial.py", line 268, in exec
    ret, ret_err = self.exec_raw(command, data_consumer=data_consumer)
  File "C:\Users\ppetit\PycharmProjects\micropython_ngt\venv\lib\site-packages\mpremote\transport_serial.py", line 254, in exec_raw
    self.exec_raw_no_follow(command)
  File "C:\Users\ppetit\PycharmProjects\micropython_ngt\venv\lib\site-packages\mpremote\transport_serial.py", line 226, in exec_raw_no_follow
    data = self.serial.read(2)
  File "C:\Users\ppetit\PycharmProjects\micropython_ngt\venv\lib\site-packages\serial\serialwin32.py", line 288, in read
    result_ok = win32.GetOverlappedResult(
KeyboardInterrupt

the only way is to reflash the firmware

• I have disabled USART3 in mpconfigboard.h but the same problem
• I have disabled LPUART1 and actived USART3 but the same problem
• I have switched REPL on USART3

I have no problem if I make

import time
from machine import UART, Pin

uart = UART(4, 57600)

time.sleep(2)

while True:
    print("test")
    uart.read(2)
    time.sleep(0.5)

or

import time
from machine import UART, Pin

uart = UART(1, 57600)

time.sleep(2)

while True:
    print("test")
    uart.read(2)
    time.sleep(0.5)

I'd like to have a look! Can you tell me where the code is? uart.c?
Thank you

[patfrench]

Looking in main.c
I see a difference between LPUART1 and LPUART2 on the IRQ (in my case I don't have LPUART2).

micropython/ports/stm32/uart.c

Lines 566 to 571 in e44a2c6

	case PYB_LPUART_1:
	uart_fn = AF_FN_LPUART;
	uart_unit = 1;
	UARTx = LPUART1;
	#if defined(STM32G0)
	irqn = USART3_4_5_6_LPUART1_IRQn;

micropython/ports/stm32/uart.c

Lines 598 to 603 in e44a2c6

	case PYB_LPUART_2:
	uart_fn = AF_FN_LPUART;
	uart_unit = 2;
	UARTx = LPUART2;
	#if defined(STM32G0)
	irqn = USART2_LPUART2_IRQn;

[patfrench]

I've just bought a NUCLEO_G0B1RE to be fixed.
I've also bought a DIP to UQFN adapter for G0B1CE to make sure the problem isn't with my custom board.

I could do some tests next week

thank you