LTC2983 Multi-Sensor Digital Temperature Measurement System Driver

Supported Devices

LTC2983

Evaluation Boards

Description

This is a Linux industrial I/O (IIO) 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 IIO for more information.

Source Code

Status

Source	Mainlined?
git	WIP

Files

Function	File
driver	drivers/iio/temperature/ltc2983.c

Example SPI device initialization

The LTC2983 supports SPI interfaces. Currently, the devices can only be instantiated via device tree. All the sensors attached on the LTC2983 channels must be described and instantiated on the devicetree.

Required devicetree properties:

compatible: Must be always one of these:
- adi,ltc2983
reg: Must be the SPI device chip select number.
interrupts: Interrupt line.

Example with thermoucouple and RTD:

spi0 {
         #address-cells = <1>;
         #size-cells = <0>;
         sensor_ltc2983: ltc2983@0 {
                 compatible = "adi,ltc2983";
                 reg = <0>;

                 #address-cells = <1>;
                 #size-cells = <0>;
                 adi,temperature-celcius;
                 interrupts = <20 IRQ_TYPE_EDGE_RISING>;
                 
                 diode5: diode@5 {
                         reg = <5>;
                         adi,sensor-type = <28>;
                 };

                 thermocouple@18 {
                         reg = <18>;
                         adi,sensor-type = <8>; //Type B
                         adi,sensor-config = <1>; //Differential, open-circuit current
                         adi,cold-junction-handle = <&diode5>;
                 };
                 
                 rsense2: rsense@2 {
                        reg = <2>;
                        adi,sensor-type = <29>;
                        adi,rsense-val-micro-ohms = /bits/ 64 <1200000000>; //1.2Kohms
                 };
                 
                 rtd@14 {
                         reg = <14>;
                         adi,sensor-type = <15>; //PT1000
                         /*2-wire, internal gnd, no current rotation*/
                         adi,sensor-config = <1>;
                         adi,excitation-current = <7>; //500uA
                         adi,rsense-handle = <&rsense2>;
                 };
        };
};

For more details, look at bindings.

Adding Linux driver support

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

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--]

Hardware configuration

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.

02 Mar 2011 15:16