Hi, Prasanna,
Regarding your question, pls refer to the following:
Q1) In busrt mode,
a) Conversion will start after trigger only right?
b) After one sequence(i.e 12 channels sampled), does it stop sampling or initiates a new conversion sequence
without any trigger?
>>>>>Burst mode means that the ADC will convert continuously once the ADC is triggered, it do not stop sampling when all 12 channels are sampled. For your application, DO NOT use burst mode.
Q 2) What is the use of start bit in SEQA_CTRL register?
>>>>>>The Start bit in SEQA_CTRL register is just used in Software Trigger mode, whne the bit is set by software, ADC convert will be triggered once.
Q3) How to acheive the required functionality for my application?
>>>>>>>Your application requires that the ADC converter is triggered by external signal from GPIO pins, once ADC is triggered, the ADC will sample all 12 channels, then stop sampling, wait for next external trigger signal. I suggest you use the example code in the LPC SDK package:
In the case, I think you can modify the void ADC_Configuration(void), change it from software triggering mode to pin hardware triggering mode.
void ADC_Configuration(void)
{
adc_config_t adcConfigStruct;
adc_conv_seq_config_t adcConvSeqConfigStruct;
/* Configure the converter. */
#if defined(FSL_FEATURE_ADC_HAS_CTRL_ASYNMODE) & FSL_FEATURE_ADC_HAS_CTRL_ASYNMODE
adcConfigStruct.clockMode = kADC_ClockSynchronousMode; /* Using sync clock source. */
#endif /* FSL_FEATURE_ADC_HAS_CTRL_ASYNMODE */
adcConfigStruct.clockDividerNumber = DEMO_ADC_CLOCK_DIVIDER;
#if defined(FSL_FEATURE_ADC_HAS_CTRL_RESOL) & FSL_FEATURE_ADC_HAS_CTRL_RESOL
adcConfigStruct.resolution = kADC_Resolution12bit;
#endif /* FSL_FEATURE_ADC_HAS_CTRL_RESOL */
#if defined(FSL_FEATURE_ADC_HAS_CTRL_BYPASSCAL) & FSL_FEATURE_ADC_HAS_CTRL_BYPASSCAL
adcConfigStruct.enableBypassCalibration = false;
#endif /* FSL_FEATURE_ADC_HAS_CTRL_BYPASSCAL */
#if defined(FSL_FEATURE_ADC_HAS_CTRL_TSAMP) & FSL_FEATURE_ADC_HAS_CTRL_TSAMP
adcConfigStruct.sampleTimeNumber = 0U;
#endif /* FSL_FEATURE_ADC_HAS_CTRL_TSAMP */
#if defined(FSL_FEATURE_ADC_HAS_CTRL_LPWRMODE) & FSL_FEATURE_ADC_HAS_CTRL_LPWRMODE
adcConfigStruct.enableLowPowerMode = false;
#endif /* FSL_FEATURE_ADC_HAS_CTRL_LPWRMODE */
#if defined(FSL_FEATURE_ADC_HAS_TRIM_REG) & FSL_FEATURE_ADC_HAS_TRIM_REG
adcConfigStruct.voltageRange = kADC_HighVoltageRange;
#endif /* FSL_FEATURE_ADC_HAS_TRIM_REG */
ADC_Init(DEMO_ADC_BASE, &adcConfigStruct);
#if !(defined(FSL_FEATURE_ADC_HAS_NO_INSEL) && FSL_FEATURE_ADC_HAS_NO_INSEL)
/* Use the temperature sensor input to channel 0. */
ADC_EnableTemperatureSensor(DEMO_ADC_BASE, true);
#endif /* FSL_FEATURE_ADC_HAS_NO_INSEL. */
/* Enable channel DEMO_ADC_SAMPLE_CHANNEL_NUMBER's conversion in Sequence A. */
adcConvSeqConfigStruct.channelMask =
(0xFFFU << DEMO_ADC_SAMPLE_CHANNEL_NUMBER); /* Includes channel DEMO_ADC_SAMPLE_CHANNEL_NUMBER. Rong modified*/
adcConvSeqConfigStruct.triggerMask = 1U; //select PIN INT0 as trigger source Rong Wrote
adcConvSeqConfigStruct.triggerPolarity = kADC_TriggerPolarityPositiveEdge;
adcConvSeqConfigStruct.enableSingleStep = false;
adcConvSeqConfigStruct.enableSyncBypass = false;
adcConvSeqConfigStruct.interruptMode = kADC_InterruptForEachSequence;
ADC_SetConvSeqAConfig(DEMO_ADC_BASE, &adcConvSeqConfigStruct);
ADC_EnableConvSeqA(DEMO_ADC_BASE, true); /* Enable the conversion sequence A. */
/* Clear the result register. */
ADC_DoSoftwareTriggerConvSeqA(DEMO_ADC_BASE);
while (!ADC_GetChannelConversionResult(DEMO_ADC_BASE, DEMO_ADC_SAMPLE_CHANNEL_NUMBER, &gAdcResultInfoStruct))
{
}
ADC_GetConvSeqAGlobalConversionResult(DEMO_ADC_BASE, &gAdcResultInfoStruct);
}
You also need to write the PINTSEL[0] regisyter to select the GPIO pin which can trigger ADC, even you have to configure the pin feature in the IOCON module for the pin.
Q4) Any example code would be helpful
>>>>>>>>>>>Pls use the ADC example in the SDK package.
You can download SDK package from the link:
Welcome | MCUXpresso SDK Builder
Hope it can help you
BR
XiangJun Rong
Hi, Prasanna,
The ADC supports external pin trigger, pls refer to the following section. For the GINT0/1 module, pls refer to the section:
Chapter 14: LPC546xx Group GPIO input interrupt (GINT0/1)
Hope it can help you
BR
XiangJun Rong
