The TCA9548A device features eight bidirectional switches that can be controlled via the I²C bus. The upstream SCL/SDA pair connects to eight downstream channels. Any individual channel or combination of channels can be selected by programming the control register. These downstream channels resolve I²C target address conflicts. For example, if eight identical digital temperature sensors are required in the application, one sensor can be connected to each channel: 0-7.

• 1-to-8 Bidirectional translating switches
• I²C Bus and SMBus compatible
• Active-low reset input
• Three address pins, allowing up to eight TCA9548A devices on the I²C bus
• Channel selection through an I2C Bus, in any combination
• Power up with all switch channels deselected
• Low RON switches
• Allows voltage-level translation between 1.8V, 2.5V, 3.3V, and 5V buses
• No glitch on power up
• Supports hot insertion
• Low standby current
• Operating power-supply voltage range of 1.65 to 5.5 V
• 5-V Tolerant inputs
• 0 to 400kHz Clock frequency
• Latch-up performance exceeds 100mA per JESD 78, class II

The last bit of the target address defines the operation (read or write) to be performed. When it is high (1), a read is selected, while a low (0) selects a write operation. Shows the TCA9548A address reference:

To call the module, you only need the “wire” library. The code below scans the module, for example:

/**
 * TCA9548 I2CScanner.ino -- I2C bus scanner for Arduino
 *
 * Based on https://playground.arduino.cc/Main/I2cScanner/
 *
 */
 
#include "Wire.h"
 
#define TCAADDR 0x70
 
void tcaselect(uint8_t i) {
  if (i > 7) return;
 
  Wire.beginTransmission(TCAADDR);
  Wire.write(1 << i);
  Wire.endTransmission();  
}
 
 
// standard Arduino setup()
void setup()
{
    while (!Serial);
    delay(1000);
 
    Wire.begin();
 
    Serial.begin(115200);
    Serial.println("\nTCAScanner ready!");
 
    for (uint8_t t=0; t<8; t++) {
      tcaselect(t);
      Serial.print("TCA Port #"); Serial.println(t);
 
      for (uint8_t addr = 0; addr<=127; addr++) {
        if (addr == TCAADDR) continue;
 
        Wire.beginTransmission(addr);
        if (!Wire.endTransmission()) {
          Serial.print("Found I2C 0x");  Serial.println(addr,HEX);
        }
      }
    }
    Serial.println("\ndone");
}
 
void loop() 
{
}

More codes on the Adafruit website: https://learn.adafruit.com/adafruit-tca9548a-1-to-8-i2c-multiplexer-breakout/arduino-wiring-and-test

https://www.ti.com/lit/ds/symlink/tca9548a.pdf

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