| 0,0 → 1,119 |
|---|
| #include <avr/io.h> |
| #include <avr/interrupt.h> |
| #include "timer2.h" |
| #include "eeprom.h" |
| #include "uart0.h" |
| #include "rc.h" |
| #include "attitude.h" |
| |
| #define HEF4017_RESET_HIGH PORTC |= (1<<PORTC6) |
| #define HEF4017_RESET_LOW PORTC &= ~(1<<PORTC6) |
| |
| #define HEF4017R_ON PORTC |= (1<<PORTC6) |
| #define HEF4017R_OFF PORTC &= ~(1<<PORTC6) |
| |
| OutputData_t outputs[MAX_OUTPUTS]; |
| |
| /***************************************************** |
| * Initialize Timer 2 |
| *****************************************************/ |
| void timer2_init(void) { |
| uint8_t sreg = SREG; |
| |
| // disable all interrupts before reconfiguration |
| cli(); |
| |
| // set PD7 as output of the PWM for pitch servo |
| DDRD |= (1 << DDD7); |
| PORTD &= ~(1 << PORTD7); // set PD7 to low |
| |
| DDRC |= (1 << DDC6); // set PC6 as output (Reset for HEF4017) |
| //PORTC &= ~(1<<PORTC6); // set PC6 to low |
| HEF4017_RESET_HIGH; // enable reset |
| |
| // Timer/Counter 2 Control Register A |
| |
| // Timer Mode is CTC (Bits: WGM22 = 0, WGM21 = 1, WGM20 = 0) |
| // PD7: Normal port operation, OC2A disconnected, (Bits: COM2A1 = 0, COM2A0 = 0) |
| // PD6: Normal port operation, OC2B disconnected, (Bits: COM2B1 = 0, COM2B0 = 0) |
| TCCR2A &= ~((1 << COM2A1) | (1 << COM2A0) | (1 << COM2B1) | (1 << COM2B0)); |
| TCCR2A |= (1 << WGM21); |
| |
| // Timer/Counter 2 Control Register B |
| |
| // Set clock divider for timer 2 to SYSKLOCK/32 = 20MHz / 32 = 625 kHz |
| // The timer increments from 0x00 to 0xFF with an update rate of 625 kHz or 1.6 us |
| // hence the timer overflow interrupt frequency is 625 kHz / 256 = 2.44 kHz or 0.4096 ms |
| |
| // divider 32 (Bits: CS022 = 0, CS21 = 1, CS20 = 1) |
| TCCR2B &= ~((1 << FOC2A) | (1 << FOC2B) | (1 << CS22)); |
| TCCR2B |= (1 << CS21) | (1 << CS20); |
| |
| // Initialize the Timer/Counter 2 Register |
| TCNT2 = 0; |
| |
| // Initialize the Output Compare Register A used for signal generation on port PD7. |
| OCR2A = 255; |
| TCCR2A |= (1 << COM2A1); // set or clear at compare match depends on value of COM2A0 |
| |
| // Timer/Counter 2 Interrupt Mask Register |
| // Enable timer output compare match A Interrupt only |
| TIMSK2 &= ~((1 << OCIE2B) | (1 << TOIE2)); |
| TIMSK2 |= (1 << OCIE2A); |
| |
| SREG = sreg; |
| } |
| |
| /***************************************************** |
| * Control Servo Position |
| *****************************************************/ |
| const uint8_t SERVO_REMAPPING[MAX_OUTPUTS] = {0,0,1,2,3,4,5,6}; |
| #define NEUTRAL_PULSELENGTH 937 |
| #define SERVOLIMIT 500 |
| #define FRAMELEN ((NEUTRAL_PULSELENGTH + SERVOLIMIT) * staticParams.ServoRefresh + 128) |
| #define MIN_PULSELENGTH (NEUTRAL_PULSELENGTH - SERVOLIMIT) |
| #define MAX_PULSELENGTH (NEUTRAL_PULSELENGTH + SERVOLIMIT) |
| |
| ISR(TIMER2_COMPA_vect) { |
| static uint16_t remainingPulseTime = 0; |
| static uint8_t servoIndex = 0; |
| static uint16_t sumOfPulseTimes = 0; |
| |
| if (!remainingPulseTime) { |
| // Pulse is over, and the next pulse has already just started. Calculate length of next pulse. |
| if (servoIndex < staticParams.ServoRefresh) { |
| // There are more signals to output. |
| remainingPulseTime = NEUTRAL_PULSELENGTH + outputs[SERVO_REMAPPING[servoIndex]].SetPoint; |
| if (remainingPulseTime < MIN_PULSELENGTH) remainingPulseTime = MIN_PULSELENGTH; |
| else if (remainingPulseTime > MAX_PULSELENGTH) remainingPulseTime = MAX_PULSELENGTH; |
| sumOfPulseTimes += remainingPulseTime; |
| servoIndex++; |
| } else { |
| // There are no more signals. Reset the counter and make this pulse cover the missing frame time. |
| remainingPulseTime = FRAMELEN - sumOfPulseTimes; |
| sumOfPulseTimes = servoIndex = 0; |
| HEF4017_RESET_HIGH; |
| } |
| } |
| |
| // Schedule the next OCR2A event. The counter is already reset at this time. |
| uint8_t delta; |
| if (remainingPulseTime > 255+128) { |
| delta = 255; |
| // Set output to reset to zero at next OCR match. It does not really matter when the output is set low again, |
| // as long as it happens once per pulse. This will, because all pulses are > 255+128 long. |
| TCCR2A &= ~(1<<COM2A0); |
| } else if (remainingPulseTime > 255) { |
| // Remaining pulse lengths in the range [256..256+something small] might cause trouble if handled the standard |
| // way, which is in chunks of 255. The remainder would be very small, possibly causing an interrupt on interrupt |
| // condition. Instead we now make a chunk of 128. The remaining chunk will then be in [128..255] which is OK. |
| delta = 128; |
| } else { |
| delta = remainingPulseTime; |
| // Set output to high at next OCR match. This is when the 4017 counter will advance by one. Also set reset low |
| TCCR2A |= (1<<COM2A0); |
| HEF4017_RESET_LOW; // implement servo-disable here, by only removing the reset signal if ServoEnabled!=0. |
| } |
| OCR2A = delta; |
| remainingPulseTime -= delta; |
| } |