Although early days, i've just ploughed into a possible noob problem! I'm needing to connect ADC (unit) via PaHub (unit) to M5 Fire (port A). All good except i'm getting way out comparison readings.. As follows

--> Using the ADC via PaHub to Fire (portA ) vs running ADC directly via Fire (portA) no PaHub.

So using ADC via PaHub reading ~ 2610 (Int), using ADC to Port A directly ~ 3120 (int), 1.2 VDC battery connected to ADC.

I'm aware that I2c pullUp resisters exist on HUB & ADC, in parallel (total ~ > 3 kOhm), which should be ok.

Any thoughts would be appreciated..

Cheers

/*
    hardware: M5Stack Fire, unit's --> M5 Mux (TCA9548A) + ADC (ADS1100)
    test00: connecting ADS board to TCA9548A then to M5 Stack Fire (port A)
    test01: TCA connected directly into Fires port A, not via TCA9548A
    connect: PORTA(21, 22)
*/

#include <Wire.h>

// ADS1100 I2C address is 0x48
// TCA9548A I2C address is 0x70

#define ADC_Addr 0x48
#define MUX_Addr 0x70

//Hub range is 0 to 5
//Select port on mux 0-5
void muxPortSelect(uint8_t i) {
  if (i > 5) return;

  Wire.beginTransmission(MUX_Addr);
  Wire.write(1 << i);
  Wire.endTransmission();
}

void setup()
{
  int error = 0;
  // Initialise I2C communication as MASTER
  Wire.begin();
  // Initialise Serial Communication, set baud rate = 115200
  Serial.begin(115200);

  // Set Mux channel
  muxPortSelect(0);  // <--- Comment out and plug ADC directly into port A

  // Set ADC
  Wire.beginTransmission(ADC_Addr);
  // Continuous conversion mode, 8 SPS, 1PGA
  //Wire.write(0x0C);
  // Stop I2C Transmission
  error = Wire.endTransmission();
  if (error == 0) {
    Serial.println("OK we have ok");
  } else {
    Serial.println("No Good -- Bummer");
  }
  delay(100);
}

void loop()
{
  unsigned int data[2];

  // Request 2 bytes of data
  Wire.requestFrom(ADC_Addr, 2);

  // Read 2 bytes of data
  // raw_adc msb, raw_adc lsb
  if (Wire.available() == 2)
  {
    data[0] = Wire.read();
    data[1] = Wire.read();
  }

  // Convert the data
  float raw_adc = (data[0] * 256.0) + data[1];
  if (raw_adc > 32767)
  {
    raw_adc -= 65536;
  }

  // Output data to serial monitor
  Serial.print("Digital Value of Analog Input : ");
  Serial.println(raw_adc);

  delay(300);
}