tca9548a

tca9548a

A Node.js module for the TCA9548A I2C 8-channel Multiplexer.

Built using node v11.9.0

This is Node.js I2C module for the TCA9548A Low-Voltage 8-Channel I2C Switch/Multiplexer.

This module uses i2c-bus which should provide access with Node.js on Linux boards like the Raspberry Pi Zero, 1, 2, or 3B and +, BeagleBone, BeagleBone Black, or Intel Edison.

Since TCA9548A needs to talk directly to the I2C bus and requires access to /dev/i2c, you will typically need run Node with elevated privileges or add your user account to the i2c group: $ sudo adduser $USER i2c. On Raspberry PI, be sure to enable I2C protocol in system configuration before proceeding.

Example Code:

//require module
//
const TCA9548A = require('tca9548a');

//module is constructed via Class so first call a new instance
//device is automatically initialized and ready to use
//addr defaults to 0x70 and bus defaults to 1
//
const tca9548a_1 = new TCA9548A({addr: 0x70, bus: 1});

//if you have more than one TCA9548A, can call another instance
//make sure that the addr is correct!!!
//
const tca9548a_2 = new TCA9548A({addr: 0x71, bus: 1});


//as an example, if using two bme280 temp sensors (sensor1 and sensor2)
//that have the same address need to enable the specific 
//multiplexer port each time you want to read from a certain device
//singlePortOn activates the port of the argument and 
//disables all other ports
//argument has to be a number 0-7
//
//use a callback to ensure that the port is enabled 
//before proceeding with other processing
//
//for example, sensor1 is attached to port 2 on the multiplexer
//
tca9548a_1.singlePortOn(2, doSomethingWithSensor());

//then read from sensor2 attached to port 6 on the multiplexer
//
tca9548a_1.singlePortOn(6, doSomethingWithSensor());


function doSomethingWithSensor () {
  //process sensor data magic
  console.log('doSomethingWithSensor called');
}



//can also enable all ports
tca9548a_1.allPortsOn();

//or disable all ports
tca9548a_1.allPortsOff();