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readDigitalPin

Read logical value from GPIO input pin

    Description

    example

    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

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    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)

    J21 header pinout of Jetson TX2 development board

    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

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

    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

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    Logical value of the pin, returned as a scalar.

    Version History

    Introduced in R2021b

    See Also

    Functions

    Objects