Hi,
I am working on a project that uses the QN9080 SIP to ADC analog values from sensors and send them over BLE. I am using multiple analog sensors, so I need to perform multiple channels of ADC by switching channels.
Here is a simple code I wrote modified from the ADC example code.
// Sensor Channel #1
ADC->CH_SEL = 0x00000040;
ADC_DoSoftwareTrigger(ADC);
while(!(ADC_GetStatusFlags(ADC) & kADC_DataReadyFlag)) {}
adcConvResult1 = ADC_GetConversionResult(ADC);
tmp_data[tmp_data_num++] = (uint8_t)(adcConvResult1 >> 15);
// Sensor Channel #2
ADC->CH_SEL = 0x00000100;
ADC_DoSoftwareTrigger(ADC);
while(!(ADC_GetStatusFlags(ADC) & kADC_DataReadyFlag)) {}
adcConvResult1 = ADC_GetConversionResult(ADC);
tmp_data[tmp_data_num++] = (uint8_t)(adcConvResult1 >> 15);
I've made the above code work inside the callback function of Ctimer. Because of the sampling rate of the analog sensor output, the callback function needs to iterate at a high rate of about 10 kHz, but the "while(!(ADC_GetStatusFlags(ADC) & kADC_DataReadyFlag)) {}" code above takes too much time.
I tested it and found that it works for speeds up to about 400 Hz, and stops at speeds higher than that without moving on from the "while(!(ADC_GetStatusFlags(ADC) & kADC_DataReadyFlag)) {}" code.
When I removed the "while(!(ADC_GetStatusFlags(ADC) & kADC_DataReadyFlag)) {}" code, it worked at rates as high as 10 kHz, but the values on each ADC channel were noisy and there was a lot of interference between the channels. This effect increased at higher rates and decreased as I slowed down.
Is there any way to lower the delay time of the "while(!(ADC_GetStatusFlags(ADC) & kADC_DataReadyFlag)) {}" code? Alternatively, I would appreciate if you could describe a way to ADC multiple channels at a high speed with minimized noise and interference.
PS. I currently have the ADC running in Single mode. If I use Scan mode, I expect the same issue to be repeated because the ADC output value is available after the ADC_DoSoftwareTrigger(ADC); repeated "while(!(ADC_GetStatusFlags(ADC) & kADC_DataReadyFlag)) {}" code.
Best regards,
Oh
