SPI ADC data acquisition

[leodk]

I am trying to make the following system:

An ADC (specifically the LTC 1407) will recieve a signal an Arduino will acquire the data using the SPI protocol. (At first i was using the Arduino UNO R4 Minima but it didnt show any result so i used the Arduino UNO R3).

(PS1: The end game is to sample the signal buta i am starting simple so i want to take 1 value enery 1s. I decided to make it easier so instead of any other signal i am supplying the ADC with a DC Voltage (from 0,1V to 1,1V))
(PS2: the ADC (LTC1407) has 2 differential channels, and for what i understood i have to always supply both of them with signal/signals, but thats not the main problem here)

The problem: I have connected everything as i should ( a) ADC to Arduino, b) the ADC with capacitpors, according to the datasheet ets) but the result in the monitor doesnt correspond to anaything and doesnt make any sense. I provide below the code i have constructed, with some pictures of the results.

I check with an oscillator that the clock, the DC, other connections were ok, i changed the wires to make sure it wasnt any of that the problem

also when i pulled out the data cable (from the ADC to the Arduino, MISO) all returning values returned zero. So far so good. But when i pullet out either the Channel 0 cables, or the Channel 1 cables, or the cable 3,3V (from arduino) the results werent affected at all, they were still coming and the same values. Also the values didnt change from 0,1V to 1,1V of signal i was sending.

Does anyone have any opinion about what might be the problem?

Thank you in advance
I am at your disposal

(i understand that the code i am providing may have some minor errors but it is my understanding that my problem is something else. Maybe i am wrong)

CODE BELOW:

#include <SPI.h>

// SPI - Arduino Pins
const int clockPin = 13;
const int slavePin = 10;
const int dataPin  = 12;

// ADC's reference voltage
const float referenceVoltage = 2.5;

// Stating the data variables
int bytesChannel0;   // 2 bytes data from Channel 0 
int bytesChannel1;   // 2 bytes data from Channel 1

// Stating frequency variables
float frequencyChannel0;
float frequencyChannel1;

// Variables to store time for frequency calculation
unsigned long startTimeChannel0;
unsigned long startTimeChannel1;



void setup()
{
  // Set up Serial communication
  Serial.begin(9600);

  // Set up SPI communication
  SPI.begin();
  
  // Set SPI pins
  pinMode(clockPin, OUTPUT);
  pinMode(slavePin, OUTPUT);
  pinMode(dataPin, INPUT);

  // Set ADC chip slave select pin high
  digitalWrite(slavePin, HIGH);

  // Initialize start time for frequency calculation
    startTimeChannel0 = micros();
    startTimeChannel1 = micros();
}



void loop()
{
  // Variables to store Voltage
  float voltageValueChannel0;
  float voltageValueChannel1;

  // Reading Channel 0, Channel 1
  readADC(bytesChannel0, bytesChannel1);

  // Convert bits to Voltage
  voltageValueChannel0 = convertToVoltage(bytesChannel0);
  voltageValueChannel1 = convertToVoltage(bytesChannel1);

  // Calculate frequency of signals
  frequencyChannel0 = calculateFrequency(startTimeChannel0);
  frequencyChannel1 = calculateFrequency(startTimeChannel1);


  // Print results for Channel 0
  Serial.print("Byte data from channel 0:");
  Serial.println(bytesChannel0);
  Serial.print("Channel 0: Voltage = ");
  Serial.print(voltageValueChannel0);
  Serial.print(" V, Frequency = ");
  Serial.print(frequencyChannel0);
  Serial.println(" Hz");

  // Print results for Channel 1
   Serial.print("Byte data from channel 1:");
  Serial.println(bytesChannel1);
  Serial.print("Channel 1: Voltage = ");
  Serial.print(voltageValueChannel1);
  Serial.print(" V, Frequency = ");
  Serial.print(frequencyChannel1);
  Serial.println(" Hz");

  delay(1000); // Wait for 1 second before taking the next set of samples
}


// Function to read ADC's data
void readADC (int &bytesChannel0, int &bytesChannel1)
{
  // Begin SPI transaction between Arduino and ADC LTC1407
  SPI.beginTransaction(SPISettings(200000, LSBFIRST, SPI_MODE0));

  // Select ADC LTC1407 by setting it low
  digitalWrite(slavePin, LOW);
  
  // Tranfer bytes to variables
  bytesChannel0=SPI.transfer(0x00);
  bytesChannel1=SPI.transfer(0x00);

  // De-select ADC LTC1407 by setting it high
  digitalWrite(slavePin, HIGH);

  // End SPI transaction between Arduino and ADC LTC1407
  SPI.endTransaction();
}



// Function to convert ADC's bit data to voltage data
float convertToVoltage(int bitData)
{
  float voltage = (bitData * referenceVoltage) / 4096.0; // 2^32
  return voltage;
}

// Function to calculate frequency using micros() function
float calculateFrequency(unsigned long &startTime)
{
  unsigned long currentTime = micros();
  unsigned long period = currentTime - startTime;

  // Convert period to frequency in Hz
  float frequency = 1000000.0 / period;

  // Update start time for the next cycle
  startTime = currentTime;  

            
  return frequency;
}

[DrDiettrich]

@leodk

may have some minor errors

I think that your code contains some fatal errors. Try to read the data sheet and Python code.

@leodk

all returning values returned zero

You should start a conversion with a rising edge on CONV, then clock in 16 bits MSB first for each channel.