Question

我的应用程序的目标是使用ATMEGA328P作为数字直接合成400赫兹正弦发生器的核心。来自微处理器的脉冲被发送到作为全H桥连接的四个高压N-MOSFET的栅极。 16位定时器1使用WGM模式10，并命令Northeast和Northwest MOSFET。 8位定时器0和8位定时器2使用模式5，分别命令Southeast和Southwest MOSFET。我能够生成具有正确宽度的脉冲，但未能使它们正确同步。在Timer1脉冲与来自Timer0和Timer2的相应脉冲之间存在一两个时钟滑移。

尝试通过设置Timer0和Timer2初始计数来补偿此延迟时，我没有成功。

#define CPU_FREQ 16000000UL
#define OUT_FREQ 400UL
#define SAMPLE_FREQ 40000UL
#define SAMPLE_COUNT SAMPLE_FREQ/OUT_FREQ/2
#define SAMPLE_MAX CPU_FREQ/SAMPLE_FREQ/2 - 1
#define TIMER0_MAX 255
#define TIMER2_MAX 255
#define TIMER0_DELAY 1
#define TIMER2_DELAY 1

void setupTimers() {
  cli();           // disable global interrupts;
  GTCCR = bit(TSM) | bit(PSRASY) | bit( PSRSYNC);
  setupTimer0();
  setupTimer1();
  setupTimer2();
  sei();           // enable global interrupts;
  GTCCR = 0;       
}

void setupTimer0() {
  // Waveform Generation Mode 5, PWM, Phase Correct
  // TOP = OCR0A, OCR1B updated at TOP,  TOV1 Flag set on BOTTOM
  // Set OC0B on Compare Match when up-counting.
  // Clear OC0B on Compare Match when down-counting
  // Clock Source Mode 1, No prescaling
  // OCIE0B, OCIE0A, TOIE0 interrupts disaabled
  // No Force Output Compare A or B
  // TCNT0 initial count compensation for OCR0A as TOP delay

  TCCR0A =   bit(COM0B1) |   bit(COM0B0) | bit(WGM00);
  TCCR0B = bit(CS00) | bit(WGM02) ;
  TCNT0 = TIMER0_DELAY;
  OCR0A  = SAMPLE_MAX;
  OCR0B  = nextOCR0B;
  TIMSK0 = 0;
}

void setupTimer1() {
  // Waveform Generation Mode 10, PWM, Phase Correct
  // TOP = ICR1, OCR1A and OCR1B updated at TOP,  TOV1 Flag set on TOP
  // Clear OC1A on Compare Match when upcounting.
  // Set OC1A on Compare Match when downcounting
  // Clear OC1B on Compare Match when upcounting.
  // Set OC1B on Compare Match when downcounting
  // Clock Source Mode 1, No prescaling
  // OCIE1B, OCIE1A, TOIE1 interrupts disaabled
  // No Force Output Compare A or B

  TCCR1A =  bit(COM1A1) | bit(COM1B1) | bit(WGM11) ;
  TCCR1B = bit(CS10) | bit(WGM13);
  TCCR1C = 0;
  TCNT1 = 0;
  OCR1A = nextOCR1A;
  OCR1B = nextOCR1B;
  ICR1 = SAMPLE_MAX;
  TIMSK1 = 0;
}

void setupTimer2() {
  // Waveform Generation Mode 5, PWM, Phase Correct
  // TOP = OCR0A, OCR1B updated at TOP,  TOV1 Flag set on BOTTOM
  // Set OC0B on Compare Match when up-counting.
  // Clear OC0B on Compare Match when down-counting
  // Clock Source Mode 1, No prescaling
  // OCIE0B, OCIE0A, TOIE0 interrupts disaabled
  // No Force Output Compare A or B
  // TCNT2 initial count compensation for OCR2A as TOP delay

  TCCR2A =   bit(COM2B1) | bit(COM2B0) | bit(WGM20);
  TCCR2B = bit(CS20) | bit(WGM22) ;
  TCNT2 = TIMER2_DELAY;
  OCR2A  = SAMPLE_MAX;
  OCR2B  = nextOCR2B;
  TIMSK2 = 0;
}

预期结果：同步脉冲实际结果：非同步脉冲

Answer 1

通过反复试验，我设法找到了解决我的问题的TIMER0_DELAY，TIMER1_DELAY和TIMER2_DELAY的组合。

在PWM正确相位模式和预分频比1：1

1 个答案: