Note: Tested on the Arduino Nano 33 IoT, Adafruit Itsy Bitsy M0, and the Adafruit Trinket M0; untested on the Arduino Zero, the Arduino MKR series, and the Adafruit Feather M0, but should work. Let me know about problems.

A fast PWM library for SAMD21G-based Arduinos

Uses the SAMD21's timers TCC0, TCC1, and TCC2 to generate PWM signals on eight pins (four on the Adafruit Trinket M0):

• Nano 33 IoT: 4, 5, 6, 7, 8, 11, 12, and 13;
• Arduino Zero (untested), Adafruit Feather M0 (untested), Adafruit Itsy Bitsy M0: 3, 4, 8, 9, 10, 11, 12, and 13;
• MKR series (untested): 2, 3, 4, 5, 6, 7, 8, and 9;
• Adafruit Trinket M0: 0, 2, 3 and 4.

Thanks go to ...

... Martin L. and Shawn Hymel for important parts of the code, and for explaining esoteric and dark stuff.

Usage:

Allowed values in square brackets.

Include the library:

#include <SAMD21turboPWM.h>

Create a TurboPWM object (called pwm here, but name as you wish):

TurboPWM pwm;

Set input clock divider and Turbo Mode (which uses a 96MHz instead of a 48Mhz input clock):

pwm.setClockDivider([1-255], [true, false]);

Initialise timer x, with prescaler, with steps (resolution), with fast aka single-slope PWM (or not -> double-slope PWM):

pwm.timer([0, 1, 2], [1, 2, 4, 8, 16, 64, 256, 1024], [2-MaxSteps], [true, false]);

• For the Arduino Nano 33 IoT, you need to initialise timer 1 for pins 4 and 7, timer 0 for pins 5, 6, 8, and 12, and timer 2 for pins 11 and 13;
• For the Arduino Zero (untested), Adafruit Feather M0 (untested), and Adafruit Itsy Bitsy M0 you need to initialise timer 0 for pins 3, 4, 10 and 12, timer 1 for pins 8 and 9, and timer 2 for pins 11 and 13;
• For the Arduino MKR series (untested), you need to initialise timer 1 for pins 2 and 3, timer 0 for pins 4, 5, 6 and 7, and timer 2 for pins 8 and 9;
• For the Adafruit Trinket M0, you need to initialise timer 0 for pins 0 and 2, and timer 1 for pins 3 and 4.

MaxSteps is 0xFFFFFF for (24-bits) timers 0 and 1, and 0xFFFF for (16 bits) timer 2.

Start PWM on a pin with a duty cycle:

pwm.analogWrite([pin number], [0-1000]);

Enable/disable a timer:

pwm.enable([0, 1, 2], [true, false]);

Get a timer's current PWM frequency:

pwm.frequency([0, 1, 2]);

Also see the header file and the examples.

If you feel like donating for this library, you can do so here: http://ocrdu.nl/donations .