USB CDC no longer needs TIM3 (which was originally used for LED(4) PWM)
and so TIM3 has been freed for general purpose use by the user. Hence
LED(4) lost its PWM capabilities.
This patch reinstates the PWM capabilities using a semi-generic piece
of code which allows to configure a timer and PWM channel to use for any
LED. But the PWM capability is only configured if the LED is set to an
intensity between 1 and 254 (ie only when needed). In that case the
relevant timer is configured for PWM. It's up to the user to make sure
the timers are not used if PWM is active.
This patch also makes sure that PWM LEDs are turned off using standard
GPIO when calling led.off() or led.intensity(0), instead of just setting
the PWM counter to zero.
TIM3 is no longer used by USB CDC for triggering outgoing data, so we
can now make it available to the user.
PWM fading on LED(4) is now gone, but will be reinstated in a new way.
This allows the DAC to use a user-specified Timer for the triggering
(instead of the default Timer(6)), while still supporting original
behaviour.
Addresses issues #1129 and #1388.
Blanket wide to all .c and .h files. Some files originating from ST are
difficult to deal with (license wise) so it was left out of those.
Also merged modpyb.h, modos.h, modstm.h and modtime.h in stmhal/.
Simple but functional timer control. More sophistication will
eventually be added, or for now just use direct register access :)
Also added pyb.freq() function to get MCU clock frequencies.
Reads ADC values into a bytearray (or similar) at a fixed rate. Needs a
better name and improved API. Also fix up DAC dma function (which also
needs a better name and API).
Damien George