54 lines
1.9 KiB
Arduino
54 lines
1.9 KiB
Arduino
|
void setup ()
|
||
|
|
{
|
||
|
|
//--- These lines set-up output at pins #9 and #10 for push-pull and are implemented in hardware ---//
|
||
|
|
digitalWrite( 9, HIGH); // set pin #9 to HIGH
|
||
|
|
pinMode ( 9, OUTPUT); // pin #9 in output mode
|
||
|
|
digitalWrite(10, LOW ); // set pin #10 to LOW
|
||
|
|
pinMode (10, OUTPUT); // pin #10 in output mode
|
||
|
|
|
||
|
|
TCCR1A = 0; // Timer/Counter Control Register 1A set to 0
|
||
|
|
TCCR1B = 0; // Timer/Counter Control Register 1B set to 0
|
||
|
|
TCNT1 = 0; // Set counter for timer #1 to 0
|
||
|
|
|
||
|
|
uint16_t freq = 9000;
|
||
|
|
uint16_t tc = 8000000/freq;
|
||
|
|
// 2 -> 4000 kHz
|
||
|
|
// 20 -> 400 kHz
|
||
|
|
// 200 -> 40 kHz
|
||
|
|
// 800 -> 10 kHz
|
||
|
|
// 1600 -> 5 kHz
|
||
|
|
// 2000 -> 4 kHz
|
||
|
|
|
||
|
|
ICR1 = tc;
|
||
|
|
OCR1A = tc/2; // number of ticks for counter 1A - Output Compare Register for A
|
||
|
|
OCR1B = tc/2; // set number of ticks for counter 1B to the same value as for 1A - Output Compare Register for B
|
||
|
|
|
||
|
|
TCCR1A |= (0 << COM1A0); // enable toggling output A - Compare Match Output A Mode bit set to 1/*
|
||
|
|
TCCR1A |= (1 << COM1A1);
|
||
|
|
TCCR1A |= (1 << COM1B0); // enable toggling output B - Compare Match Output B Mode bit set to 1
|
||
|
|
TCCR1A |= (1 << COM1B1);
|
||
|
|
|
||
|
|
// Phase and Frequency correct PWM with TOP set by ICR1
|
||
|
|
TCCR1B |= (1 << WGM13); // WGM=8
|
||
|
|
|
||
|
|
TCCR1B &= ~((1 << CS12) | (1 << CS11) | (1 << CS10)); // Clear the three clock select bits
|
||
|
|
TCCR1B |= (1 << CS10);
|
||
|
|
|
||
|
|
// see https://ww1.microchip.com/downloads/aemDocuments/documents/MCU08/ProductDocuments/DataSheets/ATmega48A-PA-88A-PA-168A-PA-328-P-DS-DS40002061B.pdf
|
||
|
|
// sections 16, 17, 18 for details
|
||
|
|
|
||
|
|
// f = fclk/(2*N*(1+OCR1A))
|
||
|
|
// N variable represents the prescale factor (1, 8, 32, 64, 128, 256, or 1024), set CS10/CS11/CS12 appropriately
|
||
|
|
|
||
|
|
// find values of OCR1A for frequencies of interest
|
||
|
|
// consider using timer #2!
|
||
|
|
|
||
|
|
}
|
||
|
|
|
||
|
|
void loop() {
|
||
|
|
// put your main code here, to run repeatedly:
|
||
|
|
|
||
|
|
}
|
||
|
|
|
||
|
|
|