read

Read data from serial device

Syntax

serialData = read(myserialdevice,count)

serialData = read(myserialdevice,count,precision)

Description

serialData = read(myserialdevice,count) returns data from the serial device.

The read method stops when it finishes reading the specified data from the device, or when the timeout period elapses.

serialData = read(myserialdevice,count,precision) overrides the default value for precision.

Note

To generate C/C++ code for this function, you must have an Embedded Coder^® license.

Examples

Connect to and Exchange Data with Serial Device

You can connect to a serial device from the MATLAB^® software, write data to the device, and read data from the device.

Create a connection from the MATLAB software to the Raspberry Pi^® hardware.

mypi = raspi

Note

If you encounter errors after running the above command, try using additional arguments (as listed in raspi) or refer to Troubleshoot Connecting Issues to Raspberry Pi Hardware.

Show the location of the Tx and Rx pins, GPIO 14 (UART0_TXD) and GPIO 15 (UART0_RXD), on the GPIO header.

showPins(mypi)

Raspberry Pi hardware uses +3.3 V. Do not connect Raspberry Pi hardware directly to devices that use higher voltages.

Connect the Raspberry Pi serial port to a +3.3 V serial device.

• To receive data, connect the RXD pin (GPIO 15 UART0_RXD) on the Raspberry Pi board to the TXD pin on the serial device.

• To transmit data, connect the TXD pin (GPIO 14 UART0_TXD) on the Raspberry Pi board to the RXD pin on the serial device.

• Connect a ground pin (GND) on the Raspberry Pi board to the GND pin on the serial device.

• Connect one of the +3.3 V pins on the Raspberry Pi board to the VCC pin on the serial device.

Research the values the serial device requires for baud, data bits, parity, and stop bit.

Create a connection, myserialdevice, from the MATLAB software to the serial device.

myserialdevice = serialdev(mypi,'/dev/serial0',9600)

myserialdevice = 

  Serialdev with Properties:

        Port: '/dev/serial0'
    BaudRate: 9600
    DataBits: 8
      Parity: 'none'
    StopBits: 1
     Timeout: 10

Write a pair of values to the serial device that requires a specific data type.

write(myserialdevice,[10 12],'uint16')

Read a 100-element array of numbers from the serial port.

output = read(myserialdevice,100,'uint16')

Increase the timeout period of the serial port.

myserialdevice.Timeout = 20

myserialdevice = 

  Serialdev with Properties:

        Port: '/dev/serial0'
    BaudRate: 115200
    DataBits: 8
      Parity: 'none'
    StopBits: 1
     Timeout: 20

Input Arguments

myserialdevice — Connection to serial device

connection

Connection to a serial device, specified as a serialdev object.

Example: myserialdevice

count — Data size

data size

Data size to read from the serial device, specified as a scalar.

Example: 2

Data Types: double

precision — Data precision

'uint8' (default) | 'char' | 'int8' | 'int16' | 'uint16' | 'int32' | 'uint32' | 'single' | 'double'

Data precision, specified as a string. Optional.

Example: 'uint8'

Data Types: char

Output Arguments

serialData — Data from serial device

serial data

Data from the serial device, returned in the device- or user-defined format.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

• The read function does not support code generation for character data.

• You can deploy read on the Raspberry Pi hardware in MATLAB Online™.

• To generate C/C++ code for this function, you must have an Embedded Coder license. For more information on selecting the right product stack according to your development goals, see Product Stack for Raspberry Pi Blockset.

Version History

Introduced in R2016b