SparkFun qwiic 6DOF LSM6DSO - issue with sample values, when connected with SparkFun qwiic I2C MUX

Sensors IMU & Motion
1

Hello again,

I have a Sparkfun thing plus c connected to a SparkFun qwiic I2C MUX, which connected with multiple SparkFun qwiic LSM6DSO.

When I using the following code, the sample values from the LSM6DSO are constantly 0.0, although properly initialization of the MUX and all of the LSM6DSO.

Can you please help me fix that problem?

#include <SPI.h>
#include <SD.h>
#include "SparkFunLSM6DSO.h"
#include <Wire.h>
#include <Arduino.h>

#define MUX_ADDR 0x70 //7-bit unshifted default I2C Address

const int numIMUs = 2;
LSM6DSO imus[numIMUs];

bool logging = false; // Define the logging flag
const int sd_cs = 5; //Thing Plus C SD card pin
String dataMessage;
File file;


//Enables a specific port number
void enableMuxPort(byte portNumber)
{
  if (portNumber > 7) portNumber = 7;

  //Read the current mux settings
  Wire.requestFrom(MUX_ADDR, 1);
  if (!Wire.available()) return; //Error
  byte settings = Wire.read();

  //Set the wanted bit to enable the port
  settings |= (1 << portNumber);

  //Write the updated settings
  Wire.beginTransmission(MUX_ADDR);
  Wire.write(settings);
  Wire.endTransmission();
}

//Disables a specific port number
void disableMuxPort(byte portNumber)
{
  if (portNumber > 7) portNumber = 7;
  //Read the current mux settings
  Wire.requestFrom(MUX_ADDR, 1);
  if (!Wire.available()) return; //Error
  byte settings = Wire.read();
  //Clear the wanted bit to disable the port
  settings &= ~(1 << portNumber);
  //Write the updated settings
  Wire.beginTransmission(MUX_ADDR);
  Wire.write(settings);
  Wire.endTransmission();
}

void setup() {
  Serial.begin(115200);

  delay(500); 

  if (!SD.begin(sd_cs)) {
    Serial.println("Card Mount Failed");
    return;
  }
  uint8_t cardType = SD.cardType();

  if (cardType == CARD_NONE) {
    Serial.println("No SD card attached");
    return;
  }

  Serial.print("SD Card Type: ");
  if (cardType == CARD_MMC) {
    Serial.println("MMC");
  } else if (cardType == CARD_SD) {
    Serial.println("SDSC");
  } else if (cardType == CARD_SDHC) {
    Serial.println("SDHC");
  } else {
    Serial.println("UNKNOWN");
  }

  uint64_t cardSize = SD.cardSize() / (1024 * 1024);
  Serial.printf("SD Card Size: %lluMB\n", cardSize);

  Wire.begin();
  delay(10);


  //Disable all eight mux ports initially, then we can enable them one at a time
  for (byte x = 0 ; x <= 7 ; x++)
  {
    disableMuxPort(x);
  }

  //Initialize all the sensors
  for (byte i = 0 ; i < numIMUs ; i++)
  {
    enableMuxPort(i); //Tell mux to connect to port X
    if (imus[i].begin()) {
      Serial.print("IMU");
      Serial.print(i + 1);
      Serial.println(" is Ready.");
    } else {
      Serial.print("Could not connect to IMU");
      Serial.println(i + 1);
      Serial.println("Freezing");
    }
    disableMuxPort(i);
  }


  file = SD.open("/datab.txt", FILE_WRITE);
  if (!file) {
    Serial.println("Failed to open file for writing");
    return;
  }
  if (file.print("Reading IMUS \r\n")) {
    Serial.println("File written");
  } else {
    Serial.println("Write failed");
  }

  Serial.println("Waiting for command: send 's' to start logging data"); 
}

void loop() {

  if (Serial.available() > 0) {
    // If there is data available from the serial port
    char command = Serial.read();

    if (command == 'S' || command == 's') {
      // Start logging data when 'S' or 's' is received
      Serial.println("Logging started.");
      Serial.println("To end logging data: send 'e'"); 
      // myLog.syncFile();
      logging = true; // Set a flag to indicate logging has started
    } else if (command == 'E' || command == 'e') {
      // Stop logging data when 'E' or 'e' is received
      Serial.println("Logging stopped.");
      logging = false; // Set the flag to indicate logging has stopped
      file.close();
    }
  }  

  if (logging) {
    for (byte i = 0; i < numIMUs; i++) {
      enableMuxPort(i);
      // Read data from the current IMU
      dataMessage = "IMU" + String(i + 1) + " AccX: " + String(imus[i].readFloatAccelX()) + "\r\n";
      Serial.println(dataMessage);
      file.print(dataMessage);

      // Calculate the timestamp in seconds
      unsigned long currentMicros = micros();
      float timestampInSeconds = currentMicros / 1000000.0;
      dataMessage = "Timestamp: " + String(timestampInSeconds) + "\r\n";
      Serial.println(dataMessage);
      file.print(dataMessage);
      disableMuxPort(i);
      // Continue to read and log data from the current IMU as needed
      delay(1);
      // delayMicroseconds(9615);
    }
  }
}

Thank you!

2

You have a very complex system, with many possibilities for making mistakes.

Did you first verify that one sensor, connected alone to the MCU, works as expected when running a library example?

Proceed step by step from that point, adding components one by one, verifying proper operation at each step.

3

Yes, I first verify one sensor, connected alone to the MCU, and it works as expected - it sampled and logged the data properly.

From that point, I connected one sensor to the MCU with I2C MUX. the MUX and sensor initialized properly. but now, the sensor sampling values are stack in 0.0

The operations in my code were taken from the I2C MUX library example.

4

If the sensor initialized properly with the multiplexer, then it sounds like I2C communications are working.

Try the simplest program possible to see if you can collect and print data from the sensor+multiplexer (remove any code related to the SD card).