【個人的備忘録】Arduino Unoのレジスタに直接アクセスしてPWMしてみた

9番ピンと10番ピンで交互にPWM

const int MOTOR1_PIN = 9;
const int MOTOR2_PIN = 10;

unsigned int PWM_FREQ = 100;
unsigned long CLOCK_FREQ = 16000000; //16MHz
unsigned int RATIO = 256; //分周比256
float duty = 0.8;
unsigned int top_val = CLOCK_FREQ / (2*RATIO*PWM_FREQ);

void setup() {
  pinMode(MOTOR1_PIN, OUTPUT);
  pinMode(MOTOR2_PIN, OUTPUT);
  TCCR1A = 0;
  TCCR1B = 0;
}

void loop() {
  // 9PinのPWM
  // モード(位相・周波数基準PWM + TOP.ICR1: WGM13 WGM12 WGM11 WGM10 = 1 0 0 0)
  TCCR1A = 0b10000000;//10:9ピンON 00:10ピンOFF 00:N/A 00:WGM11 WGM10
  TCCR1B = 0b00010100; //000:N/A  10:WGM13 WGM12  100:分周比256
  // Top値
  ICR1 = top_val;
  //duty比
  OCR1A = (unsigned int)(top_val * duty); //9ピンはOCR1A

  delay(5000);
  
  // 10PinのPWM
  // モード(位相・周波数基準PWM + TOP.ICR1: WGM13 WGM12 WGM11 WGM10 = 1 0 0 0)
  TCCR1A = 0b00100000;//10:9ピンOFF 00:10ピンON 00:N/A 00:WGM11 WGM10
  TCCR1B = 0b00010100; //000:N/A  10:WGM13 WGM12  100:分周比256
  // Top値
  ICR1 = top_val;
  //duty比
  OCR1B = (unsigned int)(top_val * duty);//10ピンはOCR1B

  delay(5000);
}

参考

https://garretlab.web.fc2.com/arduino/inside/hardware/arduino/avr/cores/arduino/wiring_analog.c/analogWrite.html
https://geek.tacoskingdom.com/blog/52#part-h3-1-h2-0
https://usicolog.nomaki.jp/engineering/avr/avrPWM.html
https://ht-deko.com/arduino/portregisters.html