libadc

Section: Linux Simple I/O Library (2)
Updated: 7 September 2025
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NAME

libadc -- Linux Simple I/O Library: A/D Input Module

SYNOPSIS

#include <libsimpleio/libadc.h>

void ADC_get_name(int32_t chip, char *name, int32_t namesize,
  int32_t *error);

void ADC_get_reference(int32_t chip, double *reference,
  int32_t *error);

void ADC_get_scale(int32_t chip, int32_t channel, double *scale,
  int32_t *error);

void ADC_open(int32_t chip, int32_t channel, int32_t *fd,
  int32_t *error);

void ADC_close(int32_t fd, int32_t *error);

void ADC_read(int32_t fd, int32_t *sample, int32_t *error);

Link with -lsimpleio.

DESCRIPTION

All functions return either 0 (upon success) or an errno value (upon failure) in *error.

ADC_get_name() fetches an information string for an A/D device. The chip number must be passed in chip. The destination buffer address must be passed in *name and the destination buffer size must be passed in namesize. The minimum size for the destination buffer is 16 bytes.

ADC_get_reference() returns the reference voltage for the A/D converter selected by the chip parameter in the *reference parameter. This will fail unless the reference voltage has been configured with the vref-supply property in a device tree overlay for the A/D converter.

ADC_get_scale() returns an A/D input scale factor (volts per step) in the *scale parameter. The A/D chip number must be passed in the chip parameter and the A/D input channel number must be passed in the channel parameter. This will fail unless the A/D chip implements scaling.

ADC_open() opens an A/D input channel device. The A/D chip number must be passed in the chip parameter and the A/D input channel number must be passed in the channel parameter. Upon success, a file descriptor for the A/D input channel device is returned in *fd.

ADC_close() closes a previously opened A/D input channel device.

ADC_read() reads a sample from an A/D input channel device. The file descriptor for an open A/D input channel device must be passed in the fd parameter. The analog sample data will be returned in the *sample parameter.

AUTHOR

Philip Munts dba Munts Technologies.