I seem to only get 0 values from the board using a Teensy 4.0

[BryanVision]

I couldn't get the library to run, so I used my own code.

#include <Wire.h>
#include <IntervalTimer.h>

// FDC1004 I2C address
#define FDC1004_I2C_ADDRESS 0x50

// FDC1004 Configuration Register Addresses
#define FDC_CONF_REG 0x0C
#define MEAS1_CONF_REG 0x08
#define MEAS2_CONF_REG 0x09
#define MEAS3_CONF_REG 0x0A
#define MEAS4_CONF_REG 0x0B

// FDC1004 Measurement Register Addresses for MSB and LSB of each channel
#define MEAS1_MSB 0x00
#define MEAS1_LSB 0x01
#define MEAS2_MSB 0x02
#define MEAS2_LSB 0x03
#define MEAS3_MSB 0x04
#define MEAS3_LSB 0x05
#define MEAS4_MSB 0x06
#define MEAS4_LSB 0x07

// IntervalTimer object
IntervalTimer myTimer;

// Function prototypes
void writeFDCRegister(uint16_t reg, uint16_t value);
void readMeasurement(void);
void readMeasurementTask(void);

void setup() {
  Serial.begin(9600);
  Wire.begin();
  delay(1000); // Wait for Serial monitor to open
  Serial.println("Initializing FDC1004 for all 4 channels...");

  // Set the measurement rate to 100S/s and enable repeat measurements
  writeFDCRegister(FDC_CONF_REG, 0x0C00);

  // Configure all 4 measurement channels for single-ended measurements
  writeFDCRegister(MEAS1_CONF_REG, 0x1C00); // Channel 1
  writeFDCRegister(MEAS2_CONF_REG, 0x1C00); // Channel 2
  writeFDCRegister(MEAS3_CONF_REG, 0x1C00); // Channel 3
  writeFDCRegister(MEAS4_CONF_REG, 0x1C00); // Channel 4

  Serial.println("FDC1004 configured for continuous measurement on all channels.");

  // Set up the hardware timer to call readMeasurementTask every 10ms
  myTimer.begin(readMeasurementTask, 10000); // 10000 microseconds = 10ms
}

void loop() {
  // The readMeasurementTask function is called every 10ms by the hardware timer
  // Nothing needed in the loop
}

void readMeasurementTask() {
  // Read measurement from all channels
  readMeasurement();
}

void readMeasurement() {
  for (int i = 0; i < 4; i++) {
    uint16_t msb = 0, lsb = 0;
    uint8_t msbReg = MEAS1_MSB + (i * 2); // Calculate MSB register for current channel
    uint8_t lsbReg = MEAS1_LSB + (i * 2); // Calculate LSB register for current channel

    // Read MSB
    Wire.beginTransmission(FDC1004_I2C_ADDRESS);
    Wire.write(msbReg >> 8);
    Wire.write(msbReg & 0xFF);
    Wire.endTransmission(false);
    Wire.requestFrom(FDC1004_I2C_ADDRESS, 2);
    if (Wire.available() == 2) {
      msb = Wire.read() << 8;
      msb |= Wire.read();
    }

    // Read LSB
    Wire.beginTransmission(FDC1004_I2C_ADDRESS);
    Wire.write(lsbReg >> 8);
    Wire.write(lsbReg & 0xFF);
    Wire.endTransmission(false);
    Wire.requestFrom(FDC1004_I2C_ADDRESS, 2);
    if (Wire.available() == 2) {
      lsb = Wire.read() << 8;
      lsb |= Wire.read();
    }
    
    // Print MSB and LSB for the current channel
    Serial.print("Channel ");
    Serial.print(i + 1);
    Serial.print(": MSB=");
    Serial.print(msb, HEX);
    Serial.print(", LSB=");
    Serial.println(lsb, HEX);
  }

  // Print a separator for readability
  Serial.println("------");
}

void writeFDCRegister(uint16_t reg, uint16_t value) {
  Wire.beginTransmission(FDC1004_I2C_ADDRESS);Channel 1: MSB=0, LSB=0
Channel 2: MSB=0, LSB=0
Channel 3: MSB=0, LSB=0
Channel 4: MSB=0, LSB=0
  Wire.write(highByte(reg)); // MSB of register address
  Wire.write(lowByte(reg)); // LSB of register address
  Wire.write(highByte(value)); // MSB of register value
  Wire.write(lowByte(value)); // LSB of register value
  Wire.endTransmission();
}

Channel 1: MSB=0, LSB=0
Channel 2: MSB=0, LSB=0
Channel 3: MSB=0, LSB=0
Channel 4: MSB=0, LSB=0

I confirmed the arduino teensy 4.0 could see the FDC1004 at its 0x50 address by running:

#include <Wire.h>

void setup() {
  Wire.begin();
  
  Serial.begin(9600);
  while (!Serial); // for Leonardo/Micro/Zero
  
  Serial.println("\nI2C Scanner");

  byte error, address;
  int nDevices = 0;

  Serial.println("Scanning...");

  for (address = 1; address < 127; address++ ) {
    // The i2c_scanner uses the return value of
    // the Write.endTransmisstion to see if
    // a device did acknowledge to the address.
    Wire.beginTransmission(address);
    error = Wire.endTransmission();

    if (error == 0) {
      Serial.print("I2C device found at address 0x");
      if (address < 16) {
        Serial.print("0");
      }
      Serial.print(address, HEX);
      Serial.println("  !");
      
      nDevices++;
    }
    else if (error == 4) {
      Serial.print("Unknown error at address 0x");
      if (address < 16) {
        Serial.print("0");
      }
      Serial.println(address, HEX);
    }    
  }
  if (nDevices == 0) {
    Serial.println("No I2C devices found\n");
  }
  else {
    Serial.println("done\n");
  }
}

void loop() {
  // nothing to do
}

I

2C Scanner
Scanning...
I2C device found at address 0x50 !
done

When running the following code to output from every address:

#include <Wire.h>

// FDC1004 I2C address
#define FDC1004_I2C_ADDRESS 0x50

void setup() {
  Serial.begin(9600);
  Wire.begin();

  // Wait for Serial monitor to open
  while (!Serial) {
    ; // wait for serial port to connect.
  }

  Serial.println("Reading FDC1004 registers...");
}

void loop() {
  // Register addresses to read
  uint8_t registersToRead[] = {
    0x00, // MEAS1_MSB
    0x01, // MEAS1_LSB
    0x02, // MEAS2_MSB
    0x03, // MEAS2_LSB
    0x04, // MEAS3_MSB
    0x05, // MEAS3_LSB
    0x06, // MEAS4_MSB
    0x07, // MEAS4_LSB
    0x08, // CONF_MEAS1
    0x09, // CONF_MEAS2
    0x0A, // CONF_MEAS3
    0x0B, // CONF_MEAS4
    0x0C, // FDC_CONF
    0x0D, // OFFSET_CAL_CIN1
    0x0E, // OFFSET_CAL_CIN2
    0x0F, // OFFSET_CAL_CIN3
    0x10, // OFFSET_CAL_CIN4
    0x11, // GAIN_CAL_CIN1
    0x12, // GAIN_CAL_CIN2
    0x13, // GAIN_CAL_CIN3
    0x14, // GAIN_CAL_CIN4
    0xFE, // Manufacturer ID
    0xFF  // Device ID
  };

  for (uint8_t reg : registersToRead) {
    readAndPrintRegister(reg);
    delay(100); // Short delay between reads
  }

  Serial.println("------");
  delay(1000); // Delay before starting over
}

void readAndPrintRegister(uint8_t reg) {
  Wire.beginTransmission(FDC1004_I2C_ADDRESS);
  Wire.write(reg);
  Wire.endTransmission(false); // End transmission but send a restart to keep the bus active
  Wire.requestFrom(FDC1004_I2C_ADDRESS, 2); // Request 2 bytes for the register value
  
  if (Wire.available() == 2) {
    uint16_t value = Wire.read() << 8; // Read MSB
    value |= Wire.read(); // Read LSB

    Serial.print("Register 0x");
    if (reg < 0x10) {
      Serial.print('0'); // Print leading zero for single digit hex numbers
    }
    Serial.print(reg, HEX);
    Serial.print(": 0x");
    Serial.println(value, HEX);
  } else {
    Serial.print("Failed to read register 0x");
    Serial.println(reg, HEX);
  }
}

We see that I can read values from all of the other addresses.

14:02:03.441 -> ------
14:02:04.454 -> Register 0x00: 0x0
14:02:04.533 -> Register 0x01: 0x0
14:02:04.659 -> Register 0x02: 0x0
14:02:04.751 -> Register 0x03: 0x0
14:02:04.845 -> Register 0x04: 0x0
14:02:04.939 -> Register 0x05: 0x0
14:02:05.017 -> Register 0x06: 0x0
14:02:05.155 -> Register 0x07: 0x0
14:02:05.248 -> Register 0x08: 0x1C00
14:02:05.341 -> Register 0x09: 0x1C00
14:02:05.435 -> Register 0x0A: 0x1C00
14:02:05.558 -> Register 0x0B: 0x1C00
14:02:05.651 -> Register 0x0C: 0x0
14:02:05.745 -> Register 0x0D: 0x0
14:02:05.839 -> Register 0x0E: 0x0
14:02:05.964 -> Register 0x0F: 0x0
14:02:06.043 -> Register 0x10: 0x0
14:02:06.135 -> Register 0x11: 0x4000
14:02:06.261 -> Register 0x12: 0x4000
14:02:06.354 -> Register 0x13: 0x4000
14:02:06.447 -> Register 0x14: 0x4000
14:02:06.538 -> Register 0xFE: 0x5449
14:02:06.663 -> Register 0xFF: 0x1004
14:02:06.757 -> ------

I have attempted to connect a number of things to channels 1-4, with no change from 0.