void setup()
{
Serial.begin (57600) ; // was for debugging
adc_setup () ; // setup ADC
pmc_enable_periph_clk (TC_INTERFACE_ID + 0*3+0) ; // clock the TC0 channel 0
TcChannel * t = &(TC0->TC_CHANNEL)[0] ; // pointer to TC0 registers for its channel 0
t->TC_CCR = TC_CCR_CLKDIS ; // disable internal clocking while setup regs
t->TC_IDR = 0xFFFFFFFF ; // disable interrupts
t->TC_SR ; // read int status reg to clear pending
t->TC_CMR = TC_CMR_TCCLKS_TIMER_CLOCK1 | // use TCLK1 (prescale by 2, = 42MHz)
TC_CMR_WAVE | // waveform mode
TC_CMR_WAVSEL_UP_RC | // count-up PWM using RC as threshold
TC_CMR_EEVT_XC0 | // Set external events from XC0 (this setup TIOB as output)
TC_CMR_ACPA_CLEAR | TC_CMR_ACPC_CLEAR |
TC_CMR_BCPB_CLEAR | TC_CMR_BCPC_CLEAR ;
t->TC_RC = 875 ; // counter resets on RC, so sets period in terms of 42MHz clock
t->TC_RA = 440 ; // roughly square wave
t->TC_CMR = (t->TC_CMR & 0xFFF0FFFF) | TC_CMR_ACPA_CLEAR | TC_CMR_ACPC_SET ; // set clear and set from RA and RC compares
t->TC_CCR = TC_CCR_CLKEN | TC_CCR_SWTRG ; // re-enable local clocking and switch to hardware trigger source.
setup_pio_TIOA0 () ; // drive Arduino pin 2 at 48kHz to bring clock out
dac_setup () ; // setup up DAC auto-triggered at 48kHz
}
void setup_pio_TIOA0 () // Configure Ard pin 2 as output from TC0 channel A (copy of trigger event)
{
PIOB->PIO_PDR = PIO_PB25B_TIOA0 ; // disable PIO control
PIOB->PIO_IDR = PIO_PB25B_TIOA0 ; // disable PIO interrupts
PIOB->PIO_ABSR |= PIO_PB25B_TIOA0 ; // switch to B peripheral
}
void dac_setup ()
{
pmc_enable_periph_clk (DACC_INTERFACE_ID) ; // start clocking DAC
DACC->DACC_CR = DACC_CR_SWRST ; // reset DAC
DACC->DACC_MR =
DACC_MR_TRGEN_EN | DACC_MR_TRGSEL (1) | // trigger 1 = TIO output of TC0
(0 << DACC_MR_USER_SEL_Pos) | // select channel 0
DACC_MR_REFRESH (0x0F) | // bit of a guess... I'm assuming refresh not needed at 48kHz
(24 << DACC_MR_STARTUP_Pos) ; // 24 = 1536 cycles which I think is in range 23..45us since DAC clock = 42MHz
DACC->DACC_IDR = 0xFFFFFFFF ; // no interrupts
DACC->DACC_CHER = DACC_CHER_CH0 << 0 ; // enable chan0
}
void dac_write (int val)
{
DACC->DACC_CDR = val & 0xFFF ;
}
void adc_setup ()
{
NVIC_EnableIRQ (ADC_IRQn) ; // enable ADC interrupt vector
ADC->ADC_IDR = 0xFFFFFFFF ; // disable interrupts
ADC->ADC_IER = 0x80 ; // enable AD7 End-Of-Conv interrupt (Arduino pin A0)
ADC->ADC_CHDR = 0xFFFF ; // disable all channels
ADC->ADC_CHER = 0x80 ; // enable just A0
ADC->ADC_CGR = 0x15555555 ; // All gains set to x1
ADC->ADC_COR = 0x00000000 ; // All offsets off
ADC->ADC_MR = (ADC->ADC_MR & 0xFFFFFFF0) | (1 << 1) | ADC_MR_TRGEN ; // 1 = trig source TIO from TC0
}
// Circular buffer, power of two.
#define BUFSIZE 0x400
#define BUFMASK 0x3FF
volatile int samples [BUFSIZE] ;
volatile int sptr = 0 ;
volatile int isr_count = 0 ; // this was for debugging
#ifdef __cplusplus
extern "C"
{
#endif
void ADC_Handler (void)
{
if (ADC->ADC_ISR & ADC_ISR_EOC7) // ensure there was an End-of-Conversion and we read the ISR reg
{
int val = *(ADC->ADC_CDR+7) ; // get conversion result
samples [sptr] = val ; // stick in circular buffer
sptr = (sptr+1) & BUFMASK ; // move pointer
dac_write (0xFFF & ~val) ; // copy inverted to DAC output FIFO
}
isr_count ++ ;
}
#ifdef __cplusplus
}
#endif
void loop()
{
}
I am trying to use this sketch which is one I found on the forum, but the only thing I can is that
What can i do ?
