LTC2983

LTC2983/LTC2984/LTC2986/LTM2985 Multi-Sensor Digital Temperature Measurement System Driver.

Supported Devices

Evaluation Boards

Description

This is a Linux industrial I/O (Linux Industrial I/O Subsystem) subsystem driver, targeting temperature sensors. The industrial I/O subsystem provides a unified framework for drivers for many different types of converters and sensors using a number of different physical interfaces (i2c, spi, etc). See Linux Industrial I/O Subsystem for more information.

Source Code

Status

Source

Mainlined?

drivers/iio/temperature/ltc2983.c

yes

Files

Function

File

driver

drivers/iio/temperature/ltc2983.c

Documentation

adi,ltc2983.yaml

Adding Linux driver support

Kernel configuration

Configure kernel with make menuconfig (alternatively use make xconfig or make qconfig).

Note

The LTC2983 driver depends CONFIG_SPI.

Linux Kernel Configuration
    Device Drivers  --->
    <*>     Industrial I/O support --->
        --- Industrial I/O support
            [--snip--]
              Temperature sensors --->
        [--snip--]
            -*- Analog Devices Multi-Sensor Digital Temperature Measurement
            System
        [--snip--]

Devicetree configuration

Example SPI device initialization

The devices can only be instantiated via device tree, along with all the sensors attached to it.

Driver testing

Each and every IIO device, typically a hardware chip, has a device folder under /sys/bus/iio/devices/iio:deviceX. Where X is the IIO index of the device. Under every of these directory folders reside a set of files, depending on the characteristics and features of the hardware device in question. These files are consistently generalized and documented in the IIO ABI documentation. In order to determine which IIO deviceX corresponds to which hardware device, the user can read the name file /sys/bus/iio/devices/iio:deviceX/name. In case the sequence in which the iio device drivers are loaded/registered is constant, the numbering is constant and may be known in advance.

root:/> cd /sys/bus/iio/devices/
root:/sys/bus/iio/devices> ls
iio:device0
root:/sys/bus/iio/devices> cd iio:device0
root:/sys/bus/iio/devices/iio:device0> ls -l
-r--r--r-- 1 root root 4096 Nov 16 11:17 dev
-r--r--r-- 1 root root 4096 Nov 16 11:17 in_temp0_raw
-r--r--r-- 1 root root 4096 Nov 16 11:17 in_temp1_raw
-r--r--r-- 1 root root 4096 Nov 16 11:17 in_temp2_raw
-r--r--r-- 1 root root 4096 Nov 16 11:17 in_temp3_raw
-r--r--r-- 1 root root 4096 Nov 16 11:17 in_temp_scale
-r--r--r-- 1 root root 4096 Nov 16 11:17 in_voltage0_raw
-r--r--r-- 1 root root 4096 Nov 16 11:17 in_voltage_scale
-r--r--r-- 1 root root 4096 Nov 16 11:17 name
lrwxrwxrwx 1 root root    0 Nov 16 11:17 of_node -> ../../../../../../../../firmware/devicetree/base/soc/spi@7e204000/ltc2983@0
drwxr-xr-x 2 root root    0 Nov 16 11:17 power
lrwxrwxrwx 1 root root    0 Nov 16 11:17 subsystem -> ../../../../../../../../bus/iio
-rw-r--r-- 1 root root 4096 Nov 16 11:17 uevent
root:/sys/bus/iio/devices/iio:device0>

The driver registers indexed in_tempN_raw and in_voltageN_raw attributes; the channel numbering depends on the configured sensors.

Identify the device

root:/sys/bus/iio/devices/iio:device0> cat name
ltc2983

Basic operation

Show temperature scale

Description: Multiply in_tempN_raw by in_temp_scale to obtain millidegrees Celsius when the device is configured for Celsius; divide by 1000 for °C. The driver reports a scale of 1000/1024.

The driver does not change the temperature-unit setting and has no Celsius/Fahrenheit selector.

root:/sys/bus/iio/devices/iio:device0> cat in_temp_scale
0.976562500

Show temperature

root:/sys/bus/iio/devices/iio:device0> cat in_temp0_raw

Show voltage

root:/sys/bus/iio/devices/iio:device0> cat in_voltage0_raw

Show Voltage scale

Description: Multiply in_voltageN_raw by in_voltage_scale to obtain millivolts; divide by 1000 for volts. The driver reports 1000/2^21 mV/code.

root:/sys/bus/iio/devices/iio:device0> cat in_voltage_scale
0.000476837

More Information