audio_telemetry_hw.h

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#ifndef AUDIO_TELEMETRY_HW_H
#define AUDIO_TELEMETRY_HW_H

#include "LPC21xx.h"
#include BOARD_CONFIG

void TIMER1_ISR(void) __attribute__((naked));

/* T1 prescaler, set T1_CLK to 5MHz, T1_CLK = PCLK / T1PCLK_DIV */

#if (PCLK == 15000000)
#define T1_PCLK_DIV     3
#else

#if (PCLK == 30000000)
#define T1_PCLK_DIV     6
#else

#if (PCLK == 60000000)
#define T1_PCLK_DIV     12
#else

#error unknown PCLK frequency
#endif
#endif
#endif

#define SAMPLES_PER_PERIOD 4
#define SAMPLE_PERIOD (PCLK/4762/SAMPLES_PER_PERIOD/T1_PCLK_DIV)

static inline void audio_telemetry_init(void)
{
  /* turn on DAC pins */
  PINSEL1 &= 1 << 19;
  PINSEL1 |= ~(1 << 18);
  /* reset & disable timer 1   */
  T1TCR = TCR_RESET;
  /* set the prescale divider  */
  T1PR = T1_PCLK_DIV - 1;
  /* select TIMER1 as IRQ       */
  VICIntSelect &= ~VIC_BIT(VIC_TIMER1);
  /* enable TIMER1 interrupt   */
  VICIntEnable = VIC_BIT(VIC_TIMER1);
  /* on slot vic slot 1        */
  VICVectCntl1 = VIC_ENABLE | VIC_TIMER1;
  /* address of the ISR        */
  VICVectAddr1 = (uint32_t)TIMER1_ISR;
  /* trigger initial match in a long time from now */
  T1MR0 = SAMPLE_PERIOD;
  /* enable interrupt on match register 0 */
  T1MCR |= TMCR_MR0_I | TMCR_MR0_R;
  /* enable timer 1 */
  T1TCR = TCR_ENABLE;
}


#define AUDIO_TELEMETRY_CHECK_RUNNING() {}


#endif /* AUDIO_TELEMETRY_HW_H */