write

R2026b

Write data to I2C device

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Syntax

write(i2c,data,dataPrecision)

Description

Add-On Required: This feature requires the MATLAB Support Package for BeagleBone Black Hardware add-on.

write(i2c,data,dataPrecision) writes data to an I2C device.

The write function stops when it finishes writing the specified data to the device, or when the timeout period elapses.

example

Examples

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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

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Connection to I2C device, specified as a i2cdev object.

Example: i2c

Data to write to I2C device, specified as vector of hexadecimal values.

Example: [hex2dec('20') hex2dec('51')]

Data Types: int8 | int16 | uint8 | uint16

Data precision, specified as a character vector. Match the data precision to the size of the register on the device. Optional.

Example: 'int16'

Data Types: char

Version History

Introduced in R2015a

See Also

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