add ARDUINO_ARCH_STM32 to take benfit of Wire.begin(sda,scl) configuration

[jmchiappa]

STM32 controllers have several I2C peripherals. So user could choose one of them by selcting the right SDA/SCL.

[olikraus]

Did you test this?
STM32 does not support the "Wire.begin(sda,scl)" configuration:

https://github.com/stm32duino/Arduino_Core_STM32/blob/d2ebcd532164a2ed2f74f9337bd86fab766ea133/libraries/Wire/src/Wire.h#L87

void begin(bool generalCall = false);
void begin(uint8_t, bool generalCall = false);

This means: Your patch can not work and will probably break the STM32 support.

[jmchiappa]

Did you test this?
STM32 does not support the "Wire.begin(sda,scl)" configuration:

https://github.com/stm32duino/Arduino_Core_STM32/blob/d2ebcd532164a2ed2f74f9337bd86fab766ea133/libraries/Wire/src/Wire.h#L87

void begin(bool generalCall = false);
void begin(uint8_t, bool generalCall = false);

This means: Your patch can not work and will probably break the STM32 support.

@olikraus ,
Yes, I did. I've tested this patch on my own stm32duino fork. A PR that adds a new "begin" method has been approved recently stm32duino/Arduino_Core_STM32#838 and will be available soon in the 1.8.0.

[olikraus]

Maybe there should be an additional check for the lib version. Is this possible?

[jmchiappa]

@olikraus ,
STM32duino 1.8.0 has been released with the new begin method stm32duino/Arduino_Core_STM32#838.
As you requested, I've successfully tested this PR with Stm32duino 1.8.0 on :

• Nucleo L476RG (I2C on pin D44 (SCL) and D43 (SDA)
• Nucleo F411RE (I2C on pin D6 (SCL) and D3 (SDA)