Kernel driver ads1015

Supported chips:

Authors:
Dirk Eibach, Guntermann & Drunck GmbH <eibach@gdsys.de>

Description

This driver implements support for the Texas Instruments ADS1015/ADS1115.

This device is a 12/16-bit A-D converter with 4 inputs.

The inputs can be used single ended or in certain differential combinations.

The inputs can be made available by 8 sysfs input files in0_input - in7_input:

  • in0: Voltage over AIN0 and AIN1.
  • in1: Voltage over AIN0 and AIN3.
  • in2: Voltage over AIN1 and AIN3.
  • in3: Voltage over AIN2 and AIN3.
  • in4: Voltage over AIN0 and GND.
  • in5: Voltage over AIN1 and GND.
  • in6: Voltage over AIN2 and GND.
  • in7: Voltage over AIN3 and GND.

Which inputs are available can be configured using platform data or devicetree.

By default all inputs are exported.

Platform Data

In linux/platform_data/ads1015.h platform data is defined, channel_data contains configuration data for the used input combinations:

  • pga is the programmable gain amplifier (values are full scale)

    • 0: +/- 6.144 V
    • 1: +/- 4.096 V
    • 2: +/- 2.048 V
    • 3: +/- 1.024 V
    • 4: +/- 0.512 V
    • 5: +/- 0.256 V

  • data_rate in samples per second

    • 0: 128
    • 1: 250
    • 2: 490
    • 3: 920
    • 4: 1600
    • 5: 2400
    • 6: 3300

Example:

struct ads1015_platform_data data = {
      .channel_data = {
              [2] = { .enabled = true, .pga = 1, .data_rate = 0 },
              [4] = { .enabled = true, .pga = 4, .data_rate = 5 },
      }
};

In this case only in2_input (FS +/- 4.096 V, 128 SPS) and in4_input (FS +/- 0.512 V, 2400 SPS) would be created.

Devicetree

Configuration is also possible via devicetree: Documentation/devicetree/bindings/hwmon/ads1015.txt