Hi all,
I've been writing a little code to try the ADC with the K20 tower dev board.
it is using ADC0 with pins ADC0_SE6b(PTD5 / 98) & ADC0_SE7b(PTD6 / 99).
I need to read the voltage on each pin as a single ADC input.
here is my init code:
void adc0_init(void)
{
/* enable ADC0 clock */
SIM_SCGC6 |= SIM_SCGC6_ADC0_MASK;
/* set pin as adc input */
PORTD_PCR5 = PORT_PCR_MUX(0); /* ADC0_SE6b */
PORTD_PCR6 = PORT_PCR_MUX(0); /* ADC0_SE7b */
/* init registers */
ADC0_CFG1 = ADLPC_NORMAL
| ADC_CFG1_ADIV(ADIV_1)
| ADLSMP_LONG
| ADC_CFG1_MODE(MODE_8)
| ADC_CFG1_ADICLK(ADICLK_BUS);
ADC0_CFG2 = MUXSEL_ADCB
| ADACKEN_DISABLED
| ADHSC_NORMAL
| ADC_CFG2_ADLSTS(ADLSTS_20);
ADC0_SC2 = ADTRG_SW
| ACFE_DISABLED
| ACFGT_LESS
| ACREN_DISABLED
| DMAEN_DISABLED
| ADC_SC2_REFSEL(REFSEL_EXT);
ADC0_SC3 = CAL_OFF
| ADCO_SINGLE
| AVGE_ENABLED
| ADC_SC3_AVGS(AVGS_32);
ADC0_SC1A = AIEN_OFF
| DIFF_SINGLE
| ADC_SC1_ADCH(31);
ADC0_SC1B = AIEN_OFF
| DIFF_SINGLE
| ADC_SC1_ADCH(31);
}
then my adc read function:
unsigned int adc0_convert(char channel_number)
{
ADC0_SC1A = AIEN_OFF
| DIFF_SINGLE
| ADC_SC1_ADCH(channel_number);
while (!(ADC0_SC1A && ADC_SC1_COCO_MASK));
return ADC0_RA;
}
now I call it from the main:
| PORTC_ISFR=0xFFFFFFFF; //Clear ISR flags |
| printf("AD conversion start\n"); |
| val = adc0_convert(6); |
| printf("ADC0_SE6b=%6d\n",val); |
| val = adc0_convert(7); |
| printf("ADC0_SE7b=%6d\n",val); |
In order to test it, I set a voltage on pins 98 & 99 of the chip, but I have a problem: voltage on PTD5 seems to be detected in channel AD7b instead of channel AD6b and voltage on PTD6 not really well detected on channel AD6b onstead of channel AD7b.
Have I misunderstood the manual? Am I missing something?
thanks for your help :smileyhappy:
Yves
