readDigitalPin

Read logical value from GPIO input pin

Since R2021b

Syntax

pinvalue = readDigitalPin(hwobj,pinNumber)

Description

pinvalue = readDigitalPin(hwobj,pinNumber) returns the logical value of a digital pin.

If the pin is not configured, this function configures the pin as a GPIO input.

If the pin is a GPIO output, or if another interface (I2C, Serial, SPI) uses the pin, this method returns an error message.

Examples

Configure Pin as Input and Read Its Value

Configure a GPIO pin as digital input and read its logical value.

Create a connection from MATLAB^® to the NVIDIA^® Jetson™ board.

hwobj = jetson

hwobj = 

  jetson with properties:

           DeviceAddress: 'jetson-board-name'
                    Port: 22
               BoardName: 'NVIDIA Jetson TX2'
             CUDAVersion: '10.0'
            cuDNNVersion: '7.6'
         TensorRTVersion: '6.0'
              SDLVersion: '1.2'
             V4L2Version: '1.14.2-1'
        GStreamerVersion: '1.14.5'
           OpenCVVersion: '4.1.1'
                 GPUInfo: [1x1 struct]
              WebcamList: []
    AvailableDigitalPins: [7 11 12 13 15 16 18 19 21 22 23 24 29 31 32 33 35 36 37 38 40]

The AvailableDigitalPins property shows the list of available digital GPIO pins.

Show the location of all the GPIO pins on your device.

showPins(hwobj)

Display the AvailableDigitalPins.

hwobj.AvailableDigitalPins

ans =

7    11    12    13    15    16    18    19    
21    22    23    24    29    31    32    33    
35    36    37    38    40

Connect your digital device to the first GPIO pin available, for example GPIO 7.

Configure pin GPIO 7 as a digital input.

configurePin(hwobj,7,'DigitalInput')

Read the value from pin GPIO 4.

readDigitalPin(hwobj,7)

ans =

  1

The logical value of 1 indicates a positive voltage signal on the pin GPIO 7.

Input Arguments

hwobj — Connection to a specific NVIDIA hardware board

jetson object

Connection to a specific NVIDIA hardware board, specified as a jetson object.

pinNumber — GPIO pin number

scalar

GPIO pin number, specified as a scalar. This argument does not accept vectors because the hardware cannot access multiple pins simultaneously.

To get a list of valid pin numbers, use the AvailableDigitalPins property of the jetson object. For example, hwobj.AvailableDigitalPins.

Example: 12

Data Types: double

Output Arguments

pinvalue — Logical value of pin

0 | 1

Logical value of the pin, returned as a scalar.

Version History

Introduced in R2021b