LMP91000EVM: ADC161S626

Hi Anniza,

What kind of troubleshooting have you tried so far? How are you powering the EVM, and how are you configuring the LMP91000? We no longer offer the SPIO-4 USB controller that is meant to be paired with the LMP91000EVM, so you will have to carefully read the schematic and make appropriate connections.

thanks,

ren

Dear Ren,

To troubleshoot the ADC, I actually didn't do much, what I did was check whether the CS was low or not. When I use Arduino and just to check the ADC161S626 the output produced is constant. Here the pin configuration, code, and results of checking the ADC on the LMP91000EVM with Arduino Mega and potentiometer

#include <SPI.h>

const int chipSelectPin = 53;

void setup() {
  // Initialize serial communication
  Serial.begin(9600);

  // Set up chip select pin
  pinMode(chipSelectPin, OUTPUT);
  digitalWrite(chipSelectPin, HIGH);

  // Initialize SPI
  SPI.begin();
  SPI.setClockDivider(SPI_CLOCK_DIV16); // Set clock speed (depends on your configuration)
  SPI.setDataMode(SPI_MODE0);           // SPI mode 0
  SPI.setBitOrder(MSBFIRST);            // MSB first
}

void loop() {
  uint16_t adcValue = readADC();
  double voltage = adcValue * (3.3 / 65535.0); // Assuming a 3.3V reference
  Serial.println(voltage, 6); // Print voltage with 6 decimal places
  delay(1000); // Delay for readability
}

uint16_t readADC() {
  digitalWrite(chipSelectPin, LOW);

  // Read 16-bit data
  uint8_t highByte = SPI.transfer(0x00);
  uint8_t lowByte = SPI.transfer(0x00);

  digitalWrite(chipSelectPin, HIGH);

  // Combine high and low byte
  return (highByte << 8) | lowByte;
}

What should i do to make the ADC on the LMP91000EVM work?

Kind regards,

Anniza

Anniza,

The LMP91000 has an I2C interface, and you are not making any I2C transactions in your Arduino code. You will have to configure the LMP91000 using its I2C interface before you can make measurements with it. Please refer to the LMP91000 datasheet.

thanks,

ren

Dear Ren,

I mean the code above is only intended to test the ADC161S626, should I also need I2C to test the ADC?

Kind regards,

Anniza

Anniza,

It is the output from LMP91000 that drives the input to the ADC. You will have to configure the LMP91000 to produce an output other than 0V.

thanks,

ren

Dear Ren,

I have already activated the LMP91000 by adding I2C communication, but the results displayed are still constant. What else do I need to do to enable the ADC on the LMP91000EVM so I can use it with both Arduino and Raspberry Pi?

Kind regards,

Anniza

Hi Anniza,

What settings are you using in the TIACN and MODECN registers? This will impact the LMP91000's output.

thanks,

ren