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willem oldemans
150
PWMFrequency.cpp
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150
PWMFrequency.cpp
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#include <Arduino.h>
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#include "PWMFrequency.h"
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void setPWMPrescaler(uint8_t pin, uint16_t prescale)
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{
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/**
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* Divides a given PWM pin frequency by a divisor.
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*
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* Arduino Leonardo AtMega 32u4 specific
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*
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* Sets the Prescaler (Divisor) for a given PWM pin. The resulting frequency
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* is equal to the base frequency divided by the given divisor:
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* - Base frequencies:
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* o The base frequency for pins 3 and 11 is 64,500 Hz.
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* o The base frequency for pins 5,6,9,10,13 is 31,250 Hz.
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* - Divisors:
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* o The divisors available on pins 3, 5, 9, 10 and 11 are: 1, 8, 64, 256, and 1024.
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* o The divisors available on pins 6 and 13 are all powers of two between 1 and 16384
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*
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* PWM frequencies are tied together in pairs of pins. If one in a
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* pair is changed, the other is also changed to match:
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* - Pins 3 and 11 are paired on timer0 8bit (Default prescale=64, Freq=977Hz)
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* - Pins 9 and 10 are paired on timer1 16bit (Default prescale=64, Freq=490Hz)
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* - Pins 5 is exclusivly on timer3 16bit (Default prescale=64, Freq=490Hz)
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* - Pins 6 and 13 are paired on timer4 10bit (default prescale=64, Freq=490Hz)
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*
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* Note: Pins 3 and 11 operate on Timer 0 changes this pins will
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* affect the user of the main time millis() functions
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*
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* Thanks to MacTester of the TonyMacX86 forums for his work in defining
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* the timings and testing this library
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*/
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//byte mode;
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#if defined __AVR_ATmega32U4__
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if(pin==3 || pin==5 || pin==9 || pin==10 || pin==11) {
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switch(prescale) {
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case 1: mode = 0b001; break;
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case 8: mode = 0b010; break;
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case 64: mode = 0b011; break;
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case 256: mode = 0b100; break;
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case 1024: mode = 0b101; break;
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default: return;
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}
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} else if(pin==6 || pin==13) {
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switch(prescale) {
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case 1: mode = 0b0001; break;
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case 2: mode = 0b0010; break;
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case 4: mode = 0b0011; break;
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case 8: mode = 0b0100; break;
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case 16: mode = 0b0101; break;
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case 32: mode = 0b0110; break;
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case 64: mode = 0b0111; break;
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case 128: mode = 0b1000; break;
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case 256: mode = 0b1001; break;
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case 512: mode = 0b1010; break;
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case 1024: mode = 0b1011; break;
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case 2048: mode = 0b1100; break;
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case 4096: mode = 0b1101; break;
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case 8192: mode = 0b1110; break;
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case 16384: mode = 0b1111; break;
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default: return;
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}
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}
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if(pin==3 || pin==11) {
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TCCR0B = TCCR1B & 0b11111000 | mode;
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} else if (pin==9 || pin==10) {
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TCCR1B = TCCR1B & 0b11111000 | mode;
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} else if (pin==5) {
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TCCR3B = TCCR3B & 0b11111000 | mode;
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} else if (pin==6 || pin==13) {
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TCCR4B = TCCR4B & 0b11110000 | mode;
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}
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}
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#elif defined (STM32F1xx)
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//stm pwm config
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#else
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/**
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* Divides a given PWM pin frequency by a divisor.
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*
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* Sets the Prescaler (Divisor) for a given PWM pin. The resulting frequency
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* is equal to the base frequency divided by the given divisor:
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* - Base frequencies:
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* o The base frequency for pins 5 and 6 is 62500 Hz.
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* o The base frequency for pins 3, 9, 10, and 11 is 31250 Hz.
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* - Divisors:
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* o The divisors available on pins 5, 6, 9, 10 are: 1,8,64,256,1024.
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* o The divisors available on pins 3, 11 are: 1,8,32,64,128,256,1024.
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*
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* PWM frequencies are tied together in pairs of pins. If one in a
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* pair is changed, the other is also changed to match:
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* - Pins 5 and 6 are paired on timer0 (Default prescale=64, Freq=977Hz)
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* - Pins 9 and 10 are paired on timer1 (Default prescale=64, Freq=490Hz)
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* - Pins 3 and 11 are paired on timer2 (Default prescale=64, Freq=490Hz)
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*
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* Note that this function will have side effects on anything else
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* that uses timers:
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* - Changes on pins 5, or 6 may cause the delay() and
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* millis() functions to stop working. Other timing-related
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* functions may also be affected.
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* - Changes on pins 9 or 10 will cause the Servo library to function
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* incorrectly.
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*
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* Thanks to macegr of the Arduino forums for his documentation of the
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* PWM frequency divisors. His post can be viewed at:
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*
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* http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1235060559/0#4
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*/
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if(pin == 5 || pin == 6 || pin == 9 || pin == 10) {
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switch(prescale) {
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case 1: mode = 0b001; break;
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case 8: mode = 0b010; break;
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case 64: mode = 0b011; break;
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case 256: mode = 0b100; break;
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case 1024: mode = 0b101; break;
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default: return;
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}
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} else if(pin == 3 || pin == 11) {
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switch(prescale) {
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case 1: mode = 0b001; break;
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case 8: mode = 0b010; break;
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case 32: mode = 0b011; break;
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case 64: mode = 0b100; break;
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case 128: mode = 0b101; break;
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case 256: mode = 0b110; break;
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case 1024: mode = 0b111; break;
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default: return;
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}
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}
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if(pin==5 || pin==6) {
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TCCR0B = TCCR0B & 0b11111000 | mode;
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} else if (pin==9 || pin==10) {
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TCCR1B = TCCR1B & 0b11111000 | mode;
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} else if (pin==3 || pin==11) {
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TCCR2B = TCCR2B & 0b11111000 | mode;
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}
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#endif
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}
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