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Added support for extra analog inputs and pwms on ATmega168.

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This commit is contained in:
David A. Mellis
2006-10-15 11:45:26 +00:00
parent debec4e37f
commit 41d86d5a75
3 changed files with 73 additions and 26 deletions
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12
targets/arduino/pins_arduino.c
View File

@ -109,15 +109,21 @@ int analog_out_pin_to_timer_array[NUM_DIGITAL_PINS] = {
NOT_ON_TIMER,
NOT_ON_TIMER,
NOT_ON_TIMER,
// on the ATmega168, digital pin 3 has pwm
// on the ATmega168, digital pin 3 has hardware pwm
#if defined(__AVR_ATmega168__)
TIMER2B,
#else
NOT_ON_TIMER,
#endif
NOT_ON_TIMER,
// on the ATmega168, digital pins 5 and 6 have hardware pwm
#if defined(__AVR_ATmega168__)
TIMER0B,
TIMER0A,
#else
NOT_ON_TIMER,
NOT_ON_TIMER,
#endif
NOT_ON_TIMER,
NOT_ON_TIMER,
TIMER1A,
@ -161,6 +167,10 @@ pin_t analog_in_pin_to_port_array[NUM_ANALOG_IN_PINS] = {
{ PC, 3 },
{ PC, 4 },
{ PC, 5 },
#if defined(__AVR_ATmega168__)
{ NOT_A_PIN, 6 },
{ NOT_A_PIN, 7 },
#endif
};
pin_t *analog_in_pin_to_port = analog_in_pin_to_port_array;

48
targets/arduino/wiring.c
View File

@ -94,6 +94,12 @@ void digitalWrite(int pin, int val)
cbi(TCCR1A, COM1B1);
#if defined(__AVR_ATmega168__)
if (analogOutPinToTimer(pin) == TIMER0A)
cbi(TCCR0A, COM0A1);
if (analogOutPinToTimer(pin) == TIMER0B)
cbi(TCCR0A, COM0B1);
if (analogOutPinToTimer(pin) == TIMER2A)
cbi(TCCR2A, COM2A1);
@ -126,6 +132,12 @@ int digitalRead(int pin)
cbi(TCCR1A, COM1B1);
#if defined(__AVR_ATmega168__)
if (analogOutPinToTimer(pin) == TIMER0A)
cbi(TCCR0A, COM0A1);
if (analogOutPinToTimer(pin) == TIMER0B)
cbi(TCCR0A, COM0B1);
if (analogOutPinToTimer(pin) == TIMER2A)
cbi(TCCR2A, COM2A1);
@ -194,6 +206,16 @@ void analogWrite(int pin, int val)
// set pwm duty
OCR1B = val;
#if defined(__AVR_ATmega168__)
} else if (analogOutPinToTimer(pin) == TIMER0A) {
// connect pwm to pin on timer 0, channel A
sbi(TCCR0A, COM0A1);
// set pwm duty
OCR0A = val;
} else if (analogOutPinToTimer(pin) == TIMER0B) {
// connect pwm to pin on timer 0, channel B
sbi(TCCR0A, COM0B1);
// set pwm duty
OCR0B = val;
} else if (analogOutPinToTimer(pin) == TIMER2A) {
// connect pwm to pin on timer 2, channel A
sbi(TCCR2A, COM2A1);
@ -328,15 +350,14 @@ SIGNAL(SIG_OVERFLOW0)
unsigned long millis()
{
// timer 0 increments every 8 cycles, and overflows when it reaches 256.
// we calculate the total number of clock cycles, then divide by the
// number of clock cycles per millisecond.
//return timer0_overflow_count * 8UL * 256UL / (F_CPU / 1000UL);
// timer 0 increments every 64 cycles, and overflows when it reaches 256.
// we would calculate the total number of clock cycles, then divide by the
// number of clock cycles per millisecond, but this overflows too often.
//return timer0_overflow_count * 64UL * 256UL / (F_CPU / 1000UL);
// calculating the total number of clock cycles overflows an
// unsigned long, so instead find 1/128th the number of clock cycles
// and divide by 1/128th the number of clock cycles per millisecond.
return timer0_overflow_count * 8UL * 2UL / (F_CPU / 128000UL);
// instead find 1/128th the number of clock cycles and divide by 1/128th
// the number of clock cycles per millisecond
return timer0_overflow_count * 64UL * 2UL / (F_CPU / 128000UL);
}
void delay(unsigned long ms)
@ -441,11 +462,20 @@ int main(void)
// timer 0 is used for millis() and delay()
timer0_overflow_count = 0;
// set timer 0 prescale factor to 8
// on the ATmega168, timer 0 is also used for fast hardware pwm
// (using phase-correct PWM would mean that timer 0 overflowed half as often
// resulting in different millis() behavior on the ATmega8 and ATmega168)
#if defined(__AVR_ATmega168__)
sbi(TCCR0A, WGM01);
sbi(TCCR0A, WGM00);
#endif
// set timer 0 prescale factor to 64
#if defined(__AVR_ATmega168__)
sbi(TCCR0B, CS01);
sbi(TCCR0B, CS00);
#else
sbi(TCCR0, CS01);
sbi(TCCR0, CS00);
#endif
// enable timer 0 overflow interrupt
#if defined(__AVR_ATmega168__)