Arduino for STM32

btw those char definitions for _end , _estack don't seemed to be correct they should more correctly be unsigned char*, but I'm not sure too, there is likely some typedefs for these.

unless _end , _estack are after all markers predefined somewhere.

well, not familiar with FreeRTOS
but I found some inspiration from
https://github.com/greiman/SdFat/blob/master/src/FreeStack.h

extern "C" char* sbrk(int incr);
inline int FreeStack() {
register uint32_t sp asm("sp");
return reinterpret_cast<char*>(sp) - reinterpret_cast<char*>(sbrk(0));
}

so ...

I reviewed the codes, and it is quite 'convoluted'
when HardwareSerial initializes
https://github.com/stm32duino/Arduino_Core_STM32/blob/main/cores/arduino/HardwareSerial.cpp#L133
it configures the pins according to PeripheralPins.c
https://github.com/stm32duino/Arduino_Core_STM32/blob/main ...

from the arduino menu, if you select "USB Support - CDC (generic 'Serial' supersede U(S)ART"
USB-Serial become the definiition of Serial

hence when you issue

void setup() {
Serial.begin();
}

that goes to USB-Serial. Serial1 .. Serial4 are still there but those are HardwareSerial which goes to ...

In addition, for your board, if you want to use usb (e.g. usb serial) you should make a variant to use the HSE crystal, otherwise normally usb may not be stable.

https://github.com/stm32duino/Arduino_Core_STM32/wiki/Add-a-new-variant-%28board%29

as apparently the crystal on your board is 8 Mhz ...

I think Serial1 .. Serial4 are pre-defined and it is not necessary to re-define them
https://github.com/stm32duino/Arduino_Core_STM32/wiki/API#hardwareserial

for the pins to use look in PeripheralPins.c
https://github.com/stm32duino/Arduino_Core_STM32/blob/main/variants/STM32F4xx/F405RGT_F415RGT ...

for single chip solution, you may want to try stm32wb55
https://github.com/stm32duino/STM32duinoBLE
https://github.com/stm32duino/Arduino_Core_STM32

but I've not tried this myself, it is more complicated than starting with plain vanilla stm32 soc without the BLE soc.
other ways are to use an ...

OK, I'm going to give Arduino another shot when the H7 board / CPU arrives.

I found a STM32H743VI board for $17 on Amazon. Wish me luck !


is it the same as this one?
https://www.aliexpress.com/item/1005006632336183.html

if it is it may 'work out of the box' e.g. with the WeAct ...

on a different note I'm not sure what to do about the 'interrupt latency' issue.

I've been wanting to observe usb (full speed) signals, that'd cost a good oscilloscope
or that maybe I can improve on my little logic analyzer.
https://www.stm32duino.com/viewtopic.php?t=116

using a timer driving DMA ...

well you may want to consider buying a ready made board

e,g
https://weactstudio.aliexpress.com/
https://www.olimex.com/
etc

if one search in the online 'flea markets' (e.g. Aliexpress) there could be more offers from other than weactstudio.

then that of course there are the Nucleos and Discovery ...