The BeagleBone Black ADC

The BeagleBone Black hardware has six analog input pins (AIN0 to AIN5). Each analog input pin has a 12-bit analog-to-digital converter (ADC) that converts the analog input voltage to a digital voltage reading.

In addition to the six input pins, the BeagleBone Black hardware has power rail and ground pins (VDD_ADC and GND_ADC).

The function readVoltage measures the voltage applied to an analog input pin relative to the ADC ground pin (GND_ADC). The ADC-driver built into the Linux® kernel returns the voltage measurement converted to a double. The values range from 0 V (GND_ADC) - 1.8 V (VDD_ADC).

Caution

  • Never connect a voltage greater than 1.8 Vacross the ADC pins. Voltages greater than 1.8 V can damage the board.

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