Silabs MGM240S (Gecko) support

[runger1101001]

PWM driver support for SiLabs Gecko type MCUs as used in the Arduino Nano Matter

Currently supports:

• 3 PWM (tested)
• 1 PWM, 2 PWM, 4 PWM (implemented but not tested)

Not yet implemented:

• 6 PWM

6 PWM support will be added, this MCU can support hardware 6 PWM with DTI for any pin combination :-)

In theory, 5 motors can be supported, in practice the MCU won't have enough pins or CPU muscle for so many, but maybe 2 could run ok.

In theory, current sensing should be possible, also low side sensing, based on DMA support and the peripheral reflex system (inter-peripheral events). I'll leave that as an exercise for another time :-)

Performance tests in closed loop mode to follow.

[runger1101001]

TODO

• add a test case to GitHub actions for Silabs
• add documentation in docs.simplefoc.com

[runger1101001]

6-PWM support added:

Up to 5 motors with 6-PWM would be theoretically supported by the timer hardware. in practice the modules won't have enough pins or CPU power for it.

If using just one or two motors, then any pins can be used for hardware 6-PWM, which is nice and makes this MCU easy to use :-)

It also means I won't bother implementing software 6-PWM.

Dead-Time insertion is possible up to 64 timer counts on rising and falling side - assuming a prescaler of 0 on a 72MHz timer clock, and PWM frequency of 25kHz, then 2% dead time work out to 31 timer counts, and 400ns of dead time on each side. You could go as high as 4% (= 800ns) at 25kHz PWM.

Other notes:

• setting polarity active-high or active-low is implemented, also separately for 6-PWM. TODO test it
• phase state setting is not implemented in 6-PWM mode TODO implement and test it
• TODO add a test case to GitHub actions for Silabs
• TODO add documentation in docs.simplefoc.com

[runger1101001]

Superseded by comprehensive and professional PR #485