scanI2CBus

Scan I2C bus device addresses

Syntax

[i2cAddresses] = scanI2CBus(bbb,bus)

Description

[i2cAddresses] = scanI2CBus(bbb,bus) returns a list of addresses for devices that connect to the I2C bus.

Examples

Connect and Exchange Data with I2C Devices

You can connect and exchange data with an I2C device on I2C bus 1.

Create a connection from the MATLAB^® software to the BeagleBone^® Black hardware.

bbb = beaglebone

bbb = 

  beaglebone with properties:

           DeviceAddress: '192.168.7.2'
               BoardName: 'BeagleBone Black Rev 00C0'
           AvailableLEDs: {'USR0'  'USR1'  'USR2'  'USR3'}
    AvailableDigitalPins: {1x29 cell}
     AvailableAnalogPins: {'AIN0'  'AIN1'  'AIN2'  'AIN3'  'AIN4'  'AIN5'  'AIN6'}
        AvailablePWMPins: {}
    AvailableSPIChannels: {}
       AvailableI2CBuses: {'i2c-1'}
    AvailableSerialPorts: {}
        AvailableWebcams: {} 

Enable I2C bus 1.

enableI2C(bbb,1)

Display AvailableI2CBuses.

bbb.AvailableI2CBuses

ans = 

    'i2c-1'    'i2c-2'

AvailableI2CBuses displays default bus 2 as i2c-1. The 1 is an internal index number. When you enable bus 1, AvailableI2CBuses displays it as i2c-2.

After physically connecting your I2C device to the I2C bus 1 pins, get the addresses of two I2C devices attached to I2C bus 1.

scanI2CBus(bbb,'i2c-2')

ans = 

     {'0x55','0x20'}

Create a connection, i2csensor, from the MATLAB software to the I2C sensor at '0x20'.

i2csensor = i2cdev(bbb,'i2c-2','0x20')

i2csensor = 

I2C with Properties:
     Bus: i2c-2
    I2CAddress: 0x20
       TimeOut: 10

Read two uint8 numbers from the sensor.

output1 = read(i2csensor,2);

Read the value of register 14 from the sensor.

output2 = readRegister(i2csensor,14);

Create a connection, i2cdisplay, from the MATLAB software to an I2C LED display at '0x55'.

i2cdisplay = i2cdev(bbb,'i2c-2','0x55')

i2cdisplay = 

I2C with Properties:
     Bus: i2c-2
    I2CAddress: 0x55
       TimeOut: 10

Write characters to the display.

write(i2cdisplay,[hex2dec('20') hex2dec('51')])

Write a scalar hexadecimal value, hex2dec('08'), to register 3 on an I2C device. uint8 is the default data type.

writeRegister(i2cdisplay,3,hex2dec('08'))

Input Arguments

bbb — Connection to BeagleBone Black hardware

beaglebone object

BeagleBone Black connection created using beaglebone, specified as an object.

bus — I2C bus identifier

'i2c-1' | 'i2c-2'

The I2C bus identifier, specified as a character vector. This property is set by the bus input argument, and it cannot be changed after object creation.

Example: 'i2c-1'

Data Types: char

Output Arguments

i2cAddresses — I2C device addresses

cell array

Addresses of I2C device attached to the bus, returned as a cell of hex values.