Wiki

Below is the source of this page. To edit this source as well as other pages on the wiki, you must login.
====== AD7192 IIO High Precision ADC Linux Driver ======

===== Supported Devices =====

  * [[adi>AD7190]]
  * [[adi>AD7192]]
  * [[adi>AD7193]] (Upstream 4.6+)
  * [[adi>AD7194]]
  * [[adi>AD7195]]
===== Reference Circuits =====

  * [[adi>CN0119]]
  * [[adi>CN0102]]
  * [[adi>CN0155]]
  * [[adi>CN0209]]
  * [[adi>CN0251]]
  * [[adi>CN0287]]
  * [[adi>CN0371]]

===== Evaluation Boards =====

  * [[adi>EVAL-AD7190EBZ]]
  * [[adi>EVAL-AD7192EBZ]]
  * [[adi>EVAL-AD7193EBZ]]
  * [[adi>EVAL-AD7194EBZ]]
  * [[adi>EVAL-AD7195EBZ]]
===== Description =====

This is a Linux industrial I/O ([[software:linux:docs:iio:iio|IIO]]) subsystem driver, targeting multi channel serial interface ADCs.
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 [[software:linux:docs:iio:iio|IIO]] for more information.

====== Source Code ======

===== Status =====

^ Source ^ Mainlined? ^
| [[git.linux.org>drivers/staging/iio/adc/ad7192.c|git]] | [[git.linux.org>drivers/staging/iio/adc/ad7192.c|yes]]  |
===== Files =====

^ Function ^ File ^
| driver  | [[staging.kernel.org>drivers/staging/iio/adc/ad7192.c]] |
| include | [[staging.kernel.org>drivers/staging/iio/adc/ad7192.h]] |

====== Example platform device initialization ======

{{page>software/linux/docs/platform_and_bus_model#Platform Data&noheader&firstseconly&noeditbtn}}

The reference voltage may vary between boards and models. The platform_data for the device's "struct device" holds this information.

<code c>
/**
 * struct ad7192_platform_data - platform/board specific information
 * @vref_mv:		the external reference voltage in millivolt
 * @ext_clk_Hz:		the external clock frequency in Hz, if not set
 *			the driver uses the internal clock (16.776 MHz)
 * @clock_source_sel:	[0..3]
 *			0 External 4.92 MHz clock connected from MCLK1 to MCLK2
 *			1 External Clock applied to MCLK2
 *			2 Internal 4.92 MHz Clock not available at the MCLK2 pin
 *			3 Internal 4.92 MHz Clock available at the MCLK2 pin
 * @refin2_en:		REFIN1/REFIN2 Reference Select (AD7190/2 only)
 * @rej60_en:		50/60Hz notch filter enable
 * @sinc3_en:		SINC3 filter enable (default SINC4)
 * @chop_en:		CHOP mode enable
 * @buf_en:		buffered input mode enable
 * @unipolar_en:	unipolar mode enable
 * @burnout_curr_en:	constant current generators on AIN(+|-) enable
 */

struct ad7192_platform_data {
	u16		vref_mv;
	u32		ext_clk_Hz;
	u8		clock_source_sel;
	bool		refin2_en;
	bool		rej60_en;
	bool		sinc3_en;
	bool		chop_en;
	bool		buf_en;
	bool		unipolar_en;
	bool		burnout_curr_en;
};
</code>

<code c>
static struct ad7192_platform_data ad7192_pdata = {
	.vref_mv		= 3300,
	.clock_source_sel	= 2,
	.refin2_en		= true,
	.rej60_en		= false,
	.sinc3_en		= false,
	.chop_en		= false,
	.buf_en			= false,
	.unipolar_en		= true,
	.burnout_curr_en	= false,
};
</code>

{{page>software/linux/docs/platform_and_bus_model#Declaring SPI slave devices&firstseconly&noeditbtn}}

Depending on the converter IC used, you may need to set the modalias accordingly, matching your part name.
It may also required to adjust max_speed_hz. Please consult the datasheet, for maximum spi clock supported by the device in question.

<code c>
static struct spi_board_info board_spi_board_info[] __initdata = {
#if defined(CONFIG_AD7192) \
	|| defined(CONFIG_AD7192_MODULE)
	{
		.modalias = "ad7192",
		.max_speed_hz = 1000000,     /* max spi clock (SCK) speed in HZ */
		.bus_num = 0,
		.chip_select = GPIO_PF10 + MAX_CTRL_CS, /* CS, change it for your board */
		.platform_data = &ad7192_pdata,
		.mode = SPI_MODE_3,
		.irq = IRQ_PF6,
	},
#endif
};
</code>

<code c>
static int __init board_init(void)
{
	[--snip--]

	spi_register_board_info(board_spi_board_info, ARRAY_SIZE(board_spi_board_info));

	[--snip--]

	return 0;
}
arch_initcall(board_init);
</code>

====== Device tree support ======
Device tree is the new method for describing non-discoverable hardware in Linux. This replaces former structure based method. For configuring a device using this drivers please follow the example bellow: 

<code>
/dts-v1/;
/plugin/;

/ {

	fragment@0 {
		target-path = "/";
		dvdd: fixedregulator@0 {
			compatible = "regulator-fixed";
			regulator-name = "fixed-supply";
			regulator-min-microvolt = <3300000>;
			regulator-max-microvolt = <3300000>;
			regulator-boot-on;
		};
	};

	fragment@1 {
		target-path = "/";
		avdd: fixedregulator@1 {
			compatible = "regulator-fixed";
			regulator-name = "fixed-supply2";
			regulator-min-microvolt = <3300000>;
			regulator-max-microvolt = <3300000>;
			regulator-boot-on;
		};
	};

	fragment@3 {
		target = <&spi0>;
			#address-cells = <1>;
			#size-cells = <0>;
			status = "okay";

		ad7190@0 {
			compatible = "adi,ad7190";
			reg = <0>;
			spi-max-frequency = <1000000>;
			spi-cpol;
			spi-cpha;
			#interrupt-cells = <2>;
			interrupts = <25 0x2>;
			interrupt-parent = <&gpio>;
			dvdd-supply = <&dvdd>;
			avdd-supply = <&avdd>;

			adi,reference-voltage-mv = /bits/ 16  <3300>;
			adi,clock-source-select = [02];
			adi,refin2-pins-enable;
			adi,rejection-60-Hz-enable;
			adi,chop-enable;
			adi,buffer-enable;
			adi,burnout-currents-enable;
			adi,sinc3-filter-enable;
			adi,unipolar-enable;
		};
	};
};
</code>

<note important> Interrupt pin connection - interrupts = <25 0x2>; this line means that gpio pin 25 is used for the interrupt and it must be connect to the DOUT/RDY pin of AD7192 along with the SPI MISO.  
 </note>
====== Adding Linux driver support ======

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

<WRAP round help>
The AD7192 Driver depends on **CONFIG_SPI**
</WRAP>

<code>
Linux Kernel Configuration
	Device Drivers  --->
		[*] Staging drivers  --->
			<*>     Industrial I/O support --->
			    --- Industrial I/O support
			    -*-   Enable ring buffer support within IIO
			    -*-     Industrial I/O lock free software ring
			    -*-   Enable triggered sampling support

			          *** Analog to digital converters ***
			    [--snip--]

			    <*>   Analog Devices AD7190 AD7192 AD7195 ADC driver

			    [--snip--]

</code>


====== Hardware configuration ======

{{:resources:tools-software:linux-drivers:iio-adc:ad7192_eval_lr.jpg?600|}}
====== Driver testing ======

{{page>software:linux:docs:iio:iio_snippets#iio device files&noheader&firstseconly&noeditbtn}}

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/> **cd /sys/bus/iio/devices/**
root:/sys/bus/iio/devices> ls
iio:device0          trigger0

root:/sys/bus/iio/devices> **cd iio:device0**

root:/sys/devices/platform/bfin-spi.0/spi0.18/iio:device0> **ls -l**
-rw-r--r--    1 root     root          4096 Jan  4 16:59 bridge_switch_en
drwxr-xr-x    4 root     root             0 Jan  4 16:59 buffer
-rw-r--r--    1 root     root          4096 Jan  4 16:59 in_voltage-in_voltage_scale
-r--r--r--    1 root     root          4096 Jan  4 16:59 in_voltage-in_voltage_scale_available
-r--r--r--    1 root     root          4096 Jan  4 16:59 in_voltage1-in_voltage2_raw
-r--r--r--    1 root     root          4096 Jan  4 16:59 in_voltage1_raw
-r--r--r--    1 root     root          4096 Jan  4 16:59 in_voltage2-in_voltage2_shorted_raw
-r--r--r--    1 root     root          4096 Jan  4 16:59 in_voltage2_raw
-r--r--r--    1 root     root          4096 Jan  4 16:59 in_voltage3-in_voltage4_raw
-r--r--r--    1 root     root          4096 Jan  4 16:59 in_voltage3_raw
-r--r--r--    1 root     root          4096 Jan  4 16:59 in_voltage4_raw
-rw-r--r--    1 root     root          4096 Jan  4 16:59 in_voltage_scale
-r--r--r--    1 root     root          4096 Jan  4 16:59 in_voltage_scale_available
-r--r--r--    1 root     root          4096 Jan  4 16:59 name
drwxr-xr-x    2 root     root             0 Jan  4 16:59 power
-rw-r--r--    1 root     root          4096 Jan  5 11:38 sampling_frequency
lrwxrwxrwx    1 root     root             0 Jan  4 16:59 subsystem -> ../../../../../bus/iio
-r--r--r--    1 root     root          4096 Jan  4 16:59 in_temp0_raw
-rw-r--r--    1 root     root          4096 Jan  4 16:59 in_temp0_scale
drwxr-xr-x    2 root     root             0 Jan  4 16:59 trigger
-rw-r--r--    1 root     root          4096 Jan  4 16:59 uevent
root:/sys/devices/platform/bfin-spi.0/spi0.18/iio:device0> 
</xterm></WRAP>

=== Show device name ===

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/devices/platform/bfin-spi.0/spi0.18/iio:device0> **cat name**
ad7192
</xterm></WRAP>

=== Set sampling frequency / update rate ===

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/devices/platform/bfin-spi.0/spi0.18/iio:device0> **cat sampling_frequency**
10
root:/sys/devices/platform/bfin-spi.0/spi0.18/iio:device0> **echo 50 > sampling_frequency**
root:/sys/devices/platform/bfin-spi.0/spi0.18/iio:device0> **cat sampling_frequency**
50
root:/sys/devices/platform/bfin-spi.0/spi0.18/iio:device0>
</xterm></WRAP>

=== Show available scales for differential input channels ===

Lists all available scales for the differential input pairs:
^ ADC Input Pair ^ Channel name ^
| AIN1(+) - AIN2(-) | in_voltage1-in_voltage2_raw |
| AIN3(+) - AIN4(-) | in_voltage3-in_voltage4_raw |
| AIN2(-) - AIN2(-) | in_voltage2-in_voltage2_shorted_raw |

Setting these directly influences the ADC input range, by altering the GAIN amplifier.

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/devices/platform/bfin-spi.0/spi0.18/iio:device0> **cat in_voltage-in_voltage_scale_available**
0.000393390 0.000196690 0.000098340 0.000049170 0.000024580 0.000012290 0.000006140 0.000003070
</xterm></WRAP>

=== Show available scales for pseudo-differential input channels ===

Lists all available scales for the differential input pairs:
^ ADC Input Pair ^ Channel name ^
| AIN1 - AINCOM | in_voltage1_raw |
| AIN2 - AINCOM | in_voltage2_raw |
| AIN3 - AINCOM | in_voltage3_raw |
| AIN4 - AINCOM | in_voltage4_raw |

Setting these directly influences the ADC input range, by altering the GAIN amplifier.

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/devices/platform/bfin-spi.0/spi0.18/iio:device0> **cat in_voltage_scale_available**
0.000393390 0.000196690 0.000098340 0.000049170 0.000024580 0.000012290 0.000006140 0.000003070
</xterm></WRAP>

=== Set scale for differential input channels ===

Scale to be applied to in1-in2_raw, in2-in3_raw in order to obtain the measured voltage in millivolts.
Allows the user to select one scale out of the available scales.
If the written scale differs from the current scale. The driver performs full and zero offset calibration on all differential input channels.

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/devices/platform/bfin-spi.0/spi0.18/iio:device0> **cat in_voltage-in_voltage_scale**
0.000393390
root:/sys/devices/platform/bfin-spi.0/spi0.18/iio:device0> **echo 0.000196690 > in_voltage-in_voltage_scale**
root:/sys/devices/platform/bfin-spi.0/spi0.18/iio:device0> **cat in_voltage-in_voltage_scale**
0.000196690
</xterm></WRAP>

=== Show channel in_voltage1 measurement ===

**Description:**\\
Raw unscaled voltage measurement on channel in_voltage1

^ ADC Input Pair ^ Channel name ^
| AIN1(+) - AIN2(-) | in_voltage1-in_voltage2_raw |
| AIN3(+) - AIN4(-) | in_voltage3-in_voltage4_raw |
| AIN2(-) - AIN2(-) | in_voltage2-in_voltage2_shorted_raw |
| AIN1 - AINCOM | in_voltage1_raw |
| AIN2 - AINCOM | in_voltage2_raw |
| AIN3 - AINCOM | in_voltage3_raw |
| AIN4 - AINCOM | in_voltage4_raw |

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/devices/platform/bfin-spi.0/spi0.18/iio:device0> **cat in1_raw**
-1
</xterm></WRAP>

**U** = //in_voltage1_raw * in_voltage_scale// = 3983772* 0.000393390 = **1567.17606708 //mV//**

=== Show channel in_voltage1-in_voltage2 measurement ===

**Description:**\\
Raw unscaled voltage measurement on channel in_voltage1-in_voltage2

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/devices/platform/bfin-spi.0/spi0.18/iio:device0> **cat in_voltage1-in_voltage2_raw**
-1
</xterm></WRAP>

**U** = //in_voltage1-in_voltage3_raw * in_voltage-in_voltage_scale// = -1 * 0.000393390 = **-0.000393390 //mV//**

=== Show internal temperature ===

**__Description:__** /sys/bus/iio/devices/iio:deviceX/in_temp0_raw \\
Shows raw unscaled temperature.


<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/devices/platform/bfin-spi.0/spi0.18/iio:device0> **cat in_temp0_raw**
-175
</xterm></WRAP>

=== Bride power-down switch control ===

**__Description:__** /sys/bus/iio/devices/iio:deviceX/bridge_switch_en \\
Writing 1 closes the bridge switch.

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/devices/platform/bfin-spi.0/spi0.18/iio:device0> **echo 1 > bridge_switch_en**
root:/sys/devices/platform/bfin-spi.0/spi0.18/iio:device0> **cat bridge_switch_en**
1
root:/sys/devices/platform/bfin-spi.0/spi0.18/iio:device0> **echo 0 > bridge_switch_en**
</xterm></WRAP>

=== AC excitation control (AD7195 only) ===

**__Description:__** /sys/bus/iio/devices/iio:deviceX/ac_excitation_en \\
Writing 1 enables AC excitation on the AD7195 ACX strobes.

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/devices/platform/bfin-spi.0/spi0.18/iio:device0> **echo 1 > ac_excitation_en**
root:/sys/devices/platform/bfin-spi.0/spi0.18/iio:device0> **cat ac_excitation_en**
1
root:/sys/devices/platform/bfin-spi.0/spi0.18/iio:device0> **echo 0 > ac_excitation_en**
</xterm></WRAP>
===== Trigger management =====

<WRAP round help>
This driver only supports it's own default trigger source **ad7192-dev0**
</WRAP>

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/devices/platform/bfin-spi.0/spi0.18/iio:device0> **cat trigger/current_trigger**
ad7192-dev0
</xterm></WRAP>

===== Buffer management =====

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/devices/platform/bfin-spi.0/spi0.18/device0/iio:buffer> ls
enable           length 
</xterm></WRAP>

{{page>software:linux:docs:iio:iio_snippets#Buffer management&noheader&firstseconly&noeditbtn}}

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/devices/platform/bfin-spi.0/spi0.18/iio:device0/scan_elements> **ls**
in_voltage1-in_voltage2_en             in_voltage2_en                 in_voltage4_en
in_voltage1-in_voltage2_index          in_voltage2_index              in_voltage4_index
in_voltage1-in_voltage2_type           in_voltage2_type               in_voltage4_type
in_voltage1_en                         in_voltage3-in_voltage4_en     in_temp0_en
in_voltage1_index                      in_voltage3-in_voltage4_index  in_temp0_index
in_voltage1_type                       in_voltage3-in_voltage4_type   in_temp0_type
in_voltage2-in_voltage2_shorted_en     in_voltage3_en                 timestamp_en
in_voltage2-in_voltage2_shorted_index  in_voltage3_index              timestamp_index
in_voltage2-in_voltage2_shorted_type   in_voltage3_type               timestamp_type  
root:/sys/devices/platform/bfin-spi.0/spi0.18/iio:device0/scan_elements>
</xterm></WRAP>

{{page>software:linux:docs:iio:iio_snippets#Typical ADC scan elements&noheader&firstseconly&noeditbtn}}
====== More Information ======

{{page>software:linux:docs:iio:iio_snippets#iio pointers&noheader&firstseconly&noeditbtn}}
Analog Devices Wiki

Page Tools
