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====== AD5504 IIO High Voltage ADC Linux Driver ======

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

  * [[adi>AD5504]]
  * [[adi>AD5501]]

===== Reference Circuits =====

  * [[adi>CN0193]]

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

  * [[adi>EVAL-AD5504EBZ]]
  * [[adi>EVAL-AD5501EBZ]]

===== Description =====

This is a Linux industrial I/O ([[software:linux:docs:iio:iio|IIO]]) subsystem driver, targeting multi-channel serial interface DACs.
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/iio/dac/ad5504.c|git]] |  [[git.linux.org>drivers/iio/dac/ad5504.c|Yes]]  |
===== Files =====

^ Function ^ File ^
| driver  | [[git.linux.org>drivers/iio/dac/ad5504.c]] |
| include | [[git.linux.org>drivers/iio/dac/ad5504.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>
static struct ad5504_platform_data ad5504_pdata = {
	.vref_mv = 30000,
};
</code>

<WRAP tip> 
This driver supports also an alternative way of specifying the reference voltage, by using the Linux regulator framework.
</WRAP>

===== Specifying reference voltage via the regulator framework =====


Below example specifies a 30 Volt reference for the SPI device 3 on SPI-Bus 0. (**spi0.3**)

<code c>
#if defined(CONFIG_REGULATOR_FIXED_VOLTAGE) || defined(CONFIG_REGULATOR_FIXED_VOLTAGE_MODULE)
static struct regulator_consumer_supply ad5504_consumer_supplies[] = {
	REGULATOR_SUPPLY("vcc", "spi0.3"),
};

static struct regulator_init_data stamp_avdd_reg_init_data = {
	.constraints	= {
		.name	= "30V0",
		.valid_ops_mask = REGULATOR_CHANGE_STATUS,
	},
	.consumer_supplies = ad5504_consumer_supplies,
	.num_consumer_supplies = ARRAY_SIZE(ad5504_consumer_supplies),
};

static struct fixed_voltage_config stamp_vdd_pdata = {
	.supply_name	= "board-30V0",
	.microvolts	= 30000000,
	.gpio		= -EINVAL,
	.enabled_at_boot = 0,
	.init_data	= &stamp_avdd_reg_init_data,
};
static struct platform_device brd_voltage_regulator = {
	.name		= "reg-fixed-voltage",
	.id		= -1,
	.num_resources	= 0,
	.dev		= {
		.platform_data	= &stamp_vdd_pdata,
	},
};
#endif
</code>

<code c>
static struct platform_device *board_devices[] __initdata = {
#if defined(CONFIG_REGULATOR_FIXED_VOLTAGE) || defined(CONFIG_REGULATOR_FIXED_VOLTAGE_MODULE)
	&brd_voltage_regulator,
#endif
};
</code>


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

	platform_add_devices(board_devices, ARRAY_SIZE(board_devices));

	[--snip--]

	return 0;
}
arch_initcall(board_init);
</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_AD5504) || \
 	defined(CONFIG_AD5504_MODULE)
	{
		/* the modalias must be the same as spi device driver name */
		.modalias = "ad5504", /* Name of spi_driver for this device */
		.max_speed_hz = 1000000,     /* max spi clock (SCK) speed in HZ */
		.bus_num = 0, /* Framework bus number */
		.chip_select = 3, /* Framework chip select */
		.mode = SPI_MODE_1,
		.irq = IRQ_PF2,
	},
#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>

====== Adding Linux driver support ======

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

<WRAP round help>
The AD5504 Driver depends on **CONFIG_SPI**
</WRAP>

<code>
Linux Kernel Configuration
	Device Drivers  --->
		<*>     Industrial I/O support --->
		    --- Industrial I/O support

		          *** Digital to analog convertors ***
		    [--snip--]
		    <*>   Analog Devices AD5504/AD5501 DAC spi driver
		    [--snip--]
</code>

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

{{:software:driver:linux:ad5504_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         iio:device0:event0

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

root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> **ls -l**
-r--r--r--    1 root     root          4096 Jan  3 14:39 name
-rw-r--r--    1 root     root          4096 Jan  3 14:39 out_voltage0_powerdown
-rw-r--r--    1 root     root          4096 Jan  3 14:39 out_voltage0_raw
-rw-r--r--    1 root     root          4096 Jan  3 14:39 out_voltage1_powerdown
-rw-r--r--    1 root     root          4096 Jan  3 14:39 out_voltage1_raw
-rw-r--r--    1 root     root          4096 Jan  3 14:39 out_voltage2_powerdown
-rw-r--r--    1 root     root          4096 Jan  3 14:39 out_voltage2_raw
-rw-r--r--    1 root     root          4096 Jan  3 14:39 out_voltage3_powerdown
-rw-r--r--    1 root     root          4096 Jan  3 14:39 out_voltage3_raw
-rw-r--r--    1 root     root          4096 Jan  3 14:39 out_voltage_powerdown_mode
-r--r--r--    1 root     root          4096 Jan  3 14:39 out_voltage_powerdown_mode_available
-r--r--r--    1 root     root          4096 Jan  3 14:39 out_voltage_scale
lrwxrwxrwx    1 root     root             0 Jan  3 14:39 subsystem -> ../../../../../bus/iio
-rw-r--r--    1 root     root          4096 Jan  3 14:39 uevent
</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/spi0.3/iio:device0> **cat name**
ad5504
</xterm></WRAP>

=== Show scale ===

**Description:**\\
scale to be applied to out_voltage0_raw in order to obtain the measured voltage in millivolts.

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> **cat out_voltage_scale**
7.324
</xterm></WRAP>

=== Set channel Y output voltage ===

**Description:**\\
/sys/bus/iio/devices/iio:deviceX/out_voltageY_raw\\

Raw (unscaled, no bias etc.) output voltage for
channel Y.

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> echo 1234 > out0_raw
</xterm></WRAP>

**U** = //out_voltage0_raw * out_voltage_scale// = 1234 * 7.324 = **9037,816 //mV//**


=== List available power down modes ===

/sys/bus/iio/devices/deviceX/out_voltage_powerdown_mode_available

**Description:**\\
Lists all available output power down modes.

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> **cat out_voltage_powerdown_mode_available**
20kohm_to_gnd three_state
</xterm></WRAP>

=== Set power down mode ===

/sys/bus/iio/devices/iio:deviceX/out_voltage_powerdown_mode

**Description:**\\
Specifies the output power down mode.
DAC output stage is disconnected from the amplifier and\\

| 20kohm_to_gnd | connected to ground via an 20kOhm resistor |
| three_state | left floating |

For a list of available output power down options read
out_voltageX_powerdown_mode_available.


<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> **echo three_state > out_voltage_powerdown_mode**
root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> **cat out_voltage_powerdown_mode**
three_state
</xterm></WRAP>

=== Enable power down mode on output Y ===

/sys/bus/iio/devices/iio:deviceX/out_voltageY_powerdown

**Description:**\\
Writing 1 causes output Y to enter the power down mode specified
by the corresponding out_voltageY_powerdown_mode. Clearing returns to
normal operation. Y may be suppressed if all outputs are
controlled together.

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> **echo 1 > out_voltage0_powerdown**
root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> **cat out_voltage0_powerdown**
1
root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> **echo 0 > out_voltage0_powerdown**
root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> **cat out_voltage0_powerdown**
0
</xterm></WRAP>

====== More Information ======

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