ADC in LPC 824

[lpcware]

Content originally posted in LPCWare by krishna.mohan on Mon Oct 19 00:16:17 MST 2015
Hi,

I've downloaded the sample project from https://www.lpcware.com/content/nxpfile/lpcopen-software-development-platform-lpc8xx-packages.
and used the adc initialization code as shown below. ADC pins are 3, 9,10.

        /* Setup ADC for 12-bit mode and normal power */
Chip_ADC_Init(LPC_ADC, 0);

/* Need to do a calibration after initialization and trim */
Chip_ADC_StartCalibration(LPC_ADC);
while (!(Chip_ADC_IsCalibrationDone(LPC_ADC))) {}

/* Setup for maximum ADC clock rate using sycnchronous clocking */
Chip_ADC_SetClockRate(LPC_ADC, ADC_MAX_SAMPLE_RATE);

/* Optionally, you can setup the ADC to use asycnchronous clocking mode.
   To enable this, mode use 'LPC_ADC->CTRL |= ADC_CR_ASYNMODE;'.
   In asycnchronous clocking mode mode, the following functions are
   used to set and determine ADC rates:
   Chip_Clock_SetADCASYNCSource();
   Chip_Clock_SetADCASYNCClockDiv();
   Chip_Clock_GetADCASYNCRate();
   clkRate = Chip_Clock_GetADCASYNCRate() / Chip_Clock_GetADCASYNCClockDiv; */

/* Setup sequencer A for ADC channel 0, EOS interrupt */
//#if defined(BOARD_NXP_LPCXPRESSO_824)
/* Setup a sequencer to do the following:
   Perform ADC conversion of ADC channels 0 only */
Chip_ADC_SetupSequencer(LPC_ADC, ADC_SEQA_IDX, (ADC_SEQ_CTRL_CHANSEL(3) | ADC_SEQ_CTRL_CHANSEL(9) |
ADC_SEQ_CTRL_CHANSEL(10) | ADC_SEQ_CTRL_MODE_EOS));


/* Enable the clock to the Switch Matrix */
Chip_Clock_EnablePeriphClock(SYSCTL_CLOCK_SWM);

/* Configure the SWM for P0-23 as the input for the ADC3 */
Chip_SWM_EnableFixedPin(SWM_FIXED_ADC3);
/* Configure the SWM for P0-17 as the input for the ADC9 */
Chip_SWM_EnableFixedPin(SWM_FIXED_ADC9);
/* Configure the SWM for P0-13 as the input for the ADC10 */
Chip_SWM_EnableFixedPin(SWM_FIXED_ADC10);

/* Disable the clock to the Switch Matrix to save power */
//Chip_Clock_DisablePeriphClock(SYSCTL_CLOCK_SWM);
//#else
//#warning "No ADC setup for this example"
//#endif

/* Setup threshold 0 low and high values to about 25% and 75% of max */
Chip_ADC_SetThrLowValue(LPC_ADC, 0, ((1 * 0xFFF) / 4));
Chip_ADC_SetThrHighValue(LPC_ADC, 0, ((3 * 0xFFF) / 4));

/* Clear all pending interrupts */
Chip_ADC_ClearFlags(LPC_ADC, Chip_ADC_GetFlags(LPC_ADC));

/* Enable ADC overrun and sequence A completion interrupts */
Chip_ADC_EnableInt(LPC_ADC, (ADC_INTEN_SEQA_ENABLE | ADC_INTEN_OVRRUN_ENABLE));

/* Use threshold 0 for ADC channel and enable threshold interrupt mode for
   channel as crossing */
Chip_ADC_SelectTH0Channels(LPC_ADC, ADC_THRSEL_CHAN_SEL_THR1(BOARD_ADC_CH));
Chip_ADC_SetThresholdInt(LPC_ADC, BOARD_ADC_CH, ADC_INTEN_THCMP_CROSSING);

/* Enable ADC NVIC interrupt */
NVIC_EnableIRQ(ADC_SEQA_IRQn);

/* Enable sequencer */
Chip_ADC_EnableSequencer(LPC_ADC, ADC_SEQA_IDX);


And for reading the ADC result

                                rawSample = Chip_ADC_GetDataReg(LPC_ADC, 3);
adc_value = ADC_DR_RESULT(rawSample);
/* Show some ADC data */
if (rawSample & (ADC_DR_OVERRUN | ADC_SEQ_GDAT_DATAVALID)) {
putLineUART("Chan: 3 \r\n");
if(rawSample & ADC_DR_OVERRUN)
putLineUART("Overrun: True \r\n");
else
putLineUART("Overrun: False \r\n");
if(rawSample & ADC_SEQ_GDAT_DATAVALID)
putLineUART("Data Valid: True\r\n");
else
putLineUART("Data Valid: False\r\n");
}
rawSample = Chip_ADC_GetDataReg(LPC_ADC, 9);
adc_value = ADC_DR_RESULT(rawSample);
/* Show some ADC data */
if (rawSample & (ADC_DR_OVERRUN | ADC_SEQ_GDAT_DATAVALID)) {
putLineUART("Chan: 9 \r\n");
if(rawSample & ADC_DR_OVERRUN)
putLineUART("Overrun: True \r\n");
else
putLineUART("Overrun: False \r\n");
if(rawSample & ADC_SEQ_GDAT_DATAVALID)
putLineUART("Data Valid: True\r\n");
else
putLineUART("Data Valid: False\r\n");
}
rawSample = Chip_ADC_GetDataReg(LPC_ADC, 10);
adc_value = ADC_DR_RESULT(rawSample);
/* Show some ADC data */
if (rawSample & (ADC_DR_OVERRUN | ADC_SEQ_GDAT_DATAVALID)) {
putLineUART("Chan: 10 \r\n");
if(rawSample & ADC_DR_OVERRUN)
putLineUART("Overrun: True \r\n");
else
putLineUART("Overrun: False \r\n");
if(rawSample & ADC_SEQ_GDAT_DATAVALID)
putLineUART("Data Valid: True\r\n");
else
putLineUART("Data Valid: False\r\n");
}

All the adc results are showing the same result. Please let me know where is the mistake. I'm not figure it out.

Regards,
Krishnamohan.

[lpcware]

Content originally posted in LPCWare by krishna.mohan on Mon Oct 19 01:39:02 MST 2015
I've downloaded sample Project from  https://www.lpcware.com/content/nxpfile/lpcopen-software-development-platform-lpc8xx-packages
Build the periph_adc project in LPC Xpresso IDE. and tried to debug project though LPC-LINK2 debugger. it was prompting error window all the time even after restarting the LPC Xpresso.

Regards,
Krishnamohan

[lpcware]

Content originally posted in LPCWare by vtw.433e on Mon Oct 19 01:01:51 MST 2015
Debug the board, or debug an application running on the board?

See http://www.nxp.com/documents/user_manual/UM10830.pdf for details of the board (including how to connect a debugger)