Subversion Repositories FlightCtrl

Rev

Rev 766 | Go to most recent revision | Show entire file | Ignore whitespace | Details | Blame | Last modification | View Log | RSS feed

Rev 766 Rev 783
Line 18... Line 18...
18 
        // disable all interrupts before reconfiguration
 18 
        // disable all interrupts before reconfiguration
19 
        cli();
 19 
        cli();
Line 20... Line 20...
20 
 
 20 
 
21 
        // set PD7 as output of the PWM for pitch servo
 21 
        // set PD7 as output of the PWM for pitch servo
22 
        DDRD  |=(1<<DDD7);
 22 
        DDRD  |=(1<<DDD7);
Line 23... Line 23...
23 
        PORTB |= (1<<PORTD7);
 23 
        PORTD |= (1<<PORTD7);
Line 24... Line 24...
24 
 
 24 
 
25 
 
 25 
 
26 
        // Timer/Counter 2 Control Register A
 26 
        // Timer/Counter 2 Control Register A
27 
 
 27 
 
28 
        // Waveform Generation Mode is Fast PWM (Bits: WGM22 = 0, WGM21 = 1, WGM20 = 1)
 28 
        // Waveform Generation Mode is Fast PWM (Bits: WGM22 = 0, WGM21 = 1, WGM20 = 1)
Line 29... Line 29...
29 
    // PD7: Clear OC2B on Compare Match, set OC2B at BOTTOM, noninverting PWM (Bits: COM2A1 = 1, COM2A0 = 0)
 29 
    // PD7: Clear OC2B on Compare Match, set OC2B at BOTTOM, non inverting PWM (Bits: COM2A1 = 1, COM2A0 = 0)
Line 30... Line 30...
30 
    // PD6: Normal port operation, OC2B disconnected, (Bits: COM2B1 = 0, COM2B0 = 0)
 30 
    // PD6: Normal port operation, OC2B disconnected, (Bits: COM2B1 = 0, COM2B0 = 0)
31 
        TCCR2A &= ~((1<<COM2B1)|(1<<COM2B0)|(1<<COM2A0));
 31 
        TCCR2A &= ~((1<<COM2B1)|(1<<COM2B0)|(1<<COM2A0));
32 
    TCCR2A |= (1<<COM2A1)|(1<<WGM21)|(1<<WGM20);
 32 
    TCCR2A |= (1<<COM2A1)|(1<<WGM21)|(1<<WGM20);
33 
 
 33 
 
34 
    // Timer/Counter 2 Control Register B
 34 
    // Timer/Counter 2 Control Register B
35 
 
 35 
 
36 
        // Set clock divider for timer 2 to SYSKLOCK/8 = 20MHz / 8 = 2.5MHz
 36 
        // Set clock divider for timer 2 to SYSKLOCK/256 = 20MHz / 256 = 78.128 kHz
Line 37... Line 37...
37 
        // The timer increments from 0x00 to 0xFF with an update rate of 2.5 MHz,
 37 
        // The timer increments from 0x00 to 0xFF with an update rate of 78.128 kHz or 12.8 us
38 
        // hence the timer overflow interrupt frequency is 2.5 MHz / 256 = 9.765 kHz or 0.1024 ms
 38 
        // hence the timer overflow interrupt frequency is 78.128 kHz / 256 = 305.176 Hz or 3.276 ms
Line 39... Line 39...
39 
 
 39 
 
40 
    // divider 8 (Bits: CS022 = 0, CS21 = 1, CS20 = 0)
 40 
    // divider 256 (Bits: CS022 = 1, CS21 = 1, CS20 = 0)
Line 41... Line 41...
41 
        TCCR2B &= ~((1<<FOC2A)|(1<<FOC2B)|(1<<WGM22));
 41 
        TCCR2B &= ~((1<<FOC2A)|(1<<FOC2B)|(1<<CS20)|(1<<WGM22));
Line 57... Line 57...
57 
 
 57 
 
58 
 
 58 
 
59 
/*****************************************************/
 59 
/*****************************************************/
60 
/*              Control Servo Position               */
 60 
/*              Control Servo Position               */
61 
/*****************************************************/
 61 
/*****************************************************/
62 
ISR(TIMER2_COMPA_vect)  // 9.765 kHz
 62 
ISR(TIMER2_COMPA_vect)  // every  OCR2A * 12.8s (compare match)
Line 63... Line 63...
63 
{
 63 
{
64 
  static uint8_t timer = 10;
 64 
  static uint8_t timer = 10;
65 
 
 65 
 
66 
  if(!timer--)
 66 
  if(!timer--)
- 
 
 67 
    {
Line 67... Line 68...
67 
    {
 68 
                 // enable PWM on PD7 in non inverting mode
68 
                 // enable PWM on PD7 in non inverting mode
 69 
                 TCCR2A &= ~(0<<COM2A0);
69 
                 TCCR2A = (TCCR2A & 0x3F)|(1<<COM2A1)|(0<<COM2A0);
 70 
                 TCCR2A |= (1<<COM2A1);
70 
 
 71