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Use BeagleBone Black ADC to Capture Analog Data

This example shows how to use the BeagleBone Black ADC to perform a simple voltage measurement using a potentiometer.

The BeagleBone Black hardware has six analog-to-digital converter (ADC) modules associated with six analog input pins. You can use these pins to measure positive voltages in the range0V (GND_ADC) -1.8V (VDD_ADC).

In addition to your BeagleBone Black board and USB cable, you must have the following equipment:

  • 1 10 kΩ potentiometer

  • Breadboard and jumper cables

The potentiometer (POT) is a three-terminal device with terminals 1 and 3 comprising the end points of a resistor embedded in the POT. The second terminal is connected to a variable wiper. As the wiper moves, the resistance values across terminals 1 and 2 and terminals 2 and 3 change. In this circuit, POT acts as a variable voltage divider. As you move the knob of the potentiometer, the voltage seen at terminal 2 changes between1.8V (VDD_ADC) and0V (GND_ADC).

Caution

  • Never connect a voltage greater than1.8 Vacross the ADC pins. Voltages greater than1.8 Vcan damage the board.

  • Always connect the negative (ground) side of a voltage source toGND_ADC. The ADC measures positive voltages only. A reversed connection can damage the board.

  1. Configure the BeagleBone Black hardware.

    • Insert a black probe lead into theGND_ADCsocket (P8_34).

    • Insert a white probe lead into theVDD_ADCsocket (P8_32).

    • Insert a red probe lead into theAIN0socket (P8_39)

    • Connect the white lead to terminal 1 of the POT. Connect the black lead to terminal 3 of the POT. Connect the red lead to terminal 2 of the POT.

  2. Start MATLAB®.

  3. Connect the BeagleBone Black board to a host computer USB port and wait about 30 seconds for the board to start.

  4. Connect the BeagleBone Black driver interface to the board.

    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: {}

  5. Verify that'AIN0'is an available analog pin.

    bbb.AvailableAnalogPins
    ans = 'AIN0' 'AIN1' 'AIN2' 'AIN3' 'AIN4' 'AIN5' 'AIN6'

  6. 将锅设置为最低位置。读了沃尔特ge.

    v_AA = readVoltage(bbb,'AIN0')
    vv_AA = 1.8

  7. Set the POT to its highest position. Read the voltage.

    v_AA = readVoltage(bbb,'AIN0')
    vv_AA = 0.0