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—resources:tools-software:linux-drivers:misc:dpot [11 Mar 2015 11:04] – [Status] fix alignment Lars-Peter Clausen
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 +====== Digital Potentiometer Linux Driver ======
 +
 +===== Supported Devices =====
 +
 +  * [[adi>AD5160]]
 +  * [[adi>AD5161]]
 +  * [[adi>AD5165]]
 +  * [[adi>AD5170]]
 +  * [[adi>AD5171]]
 +  * [[adi>AD5172]]
 +  * [[adi>AD5201]]
 +  * [[adi>AD5203]]
 +  * [[adi>AD5204]]
 +  * [[adi>AD5206]]
 +  * [[adi>AD5207]]
 +  * [[adi>AD5231]]
 +  * [[adi>AD5232]]
 +  * [[adi>AD5233]]
 +  * [[adi>AD5235]]
 +  * [[adi>AD5242]]
 +  * [[adi>AD5243]]
 +  * [[adi>AD5245]]
 +  * [[adi>AD5246]]
 +  * [[adi>AD5247]]
 +  * [[adi>AD5248]]
 +  * [[adi>AD5251]]
 +  * [[adi>AD5252]]
 +  * [[adi>AD5253]]
 +  * [[adi>AD5254]]
 +  * [[adi>AD5255]]
 +  * [[adi>AD5258]]
 +  * [[adi>AD5259]]
 +  * [[adi>AD5260]]
 +  * [[adi>AD5262]]
 +  * [[adi>AD5270]]
 +  * [[adi>AD5271]]
 +  * [[adi>AD5272]]
 +  * [[adi>AD5273]]
 +  * [[adi>AD5274]]
 +  * [[adi>AD5280]]
 +  * [[adi>AD5282]]
 +  * [[adi>AD5290]]
 +  * [[adi>AD5291]]
 +  * [[adi>AD5292]]
 +  * [[adi>AD5293]]
 +  * [[adi>AD7376]]
 +  * [[adi>AD8400]]
 +  * [[adi>AD8402]]
 +  * [[adi>AD8403]]
 +  * [[adi>ADN2850]]
 +  * [[adi>ADN2860]]
 +
 +===== Reference Circuits =====
 +
 +  * [[adi>CN0112]]
 +  * [[adi>CN0114]]
 +  * [[adi>CN0287]]
 +
 +===== Evaluation Boards =====
 +
 +  * [[adi>EVAL-AD5160EBZ]]
 +  * [[adi>EVAL-AD5161EBZ]]
 +  * [[adi>EVAL-AD5165EBZ]]
 +  * [[adi>EVAL-AD5171DBZ]]
 +  * [[adi>EVAL-AD5172SDZ]]
 +  * [[adi>EVAL-AD5232SDZ]]
 +  * [[adi>EVAL-AD5235SDZ]]
 +  * [[adi>EVAL-AD5242EBZ]]
 +  * [[adi>EVAL-AD5243SDZ]]
 +  * [[adi>EVAL-AD5245EBZ]]
 +  * [[adi>EVAL-AD5246DBZ]]
 +  * [[adi>EVAL-AD5247DBZ]]
 +  * [[adi>EVAL-AD5252SDZ]]
 +  * [[adi>EVAL-AD5254SDZ]]
 +  * [[adi>EVAL-AD5258DBZ]]
 +  * [[adi>EVAL-AD5259DBZ]]
 +  * [[adi>EVAL-AD5262EBZ]]
 +  * [[adi>EVAL-AD5270SDZ]]
 +  * [[adi>EVAL-AD5272SDZ]]
 +  * [[adi>EVAL-AD5273DBZ]]
 +  * [[adi>EVAL-AD5282EBZ]]
 +  * [[adi>EVAL-AD5290EBZ]]
 +  * [[adi>EVAL-AD5292EBZ]]
 +  * [[adi>EVAL-AD7376EBZ]]
 +  * [[adi>EVAL-AD8403SDZ]]
 +  * [[adi>EVAL-ADN2850SDZ]]
 +  * PMOD-DPOT
 +
 +<source trunk/drivers/misc/ad525x_dpot.c:/DEVID/-/Documentation/ c linux-kernel>
 +===== Description =====
 +
 +The ad525x_dpot driver exports a simple sysfs interface.  This allows you to
 +work with the immediate resistance settings as well as update the saved startup
 +settings.  Access to the factory programmed tolerance is also provided, but
 +interpretation of this settings is required by the end application according to
 +the specific part in use.
 + 
 +==== Files ====
 +
 +Each dpot device will have a set of **eeprom**, **rdac**, and **tolerance** files.  How
 +many depends on the actual part you have, as will the range of allowed values.
 + 
 +The **eeprom** files are used to program the startup value of the device.
 + 
 +The **rdac** files are used to program the immediate value of the device.
 + 
 +The **tolerance** files are the read-only factory programmed tolerance settings
 +and may vary greatly on a part-by-part basis.  For exact interpretation of
 +this field, please consult the datasheet for your part.  This is presented
 +as a hex file for easier parsing.
 +
 +
 +====== Source Code ======
 +
 +===== Status =====
 +
 +^ Source ^ Mainlined? ^
 +| [[git.linux.org>drivers/misc/ad525x_dpot.c|git]] | [[git.linux.org>drivers/misc/ad525x_dpot.c|Yes]] |
 +
 +===== Files =====
 +
 +^ Function ^ File ^
 +| driver  | [[git.linux.org>drivers/misc/ad525x_dpot.c]] |
 +| i2c bus support  | [[git.linux.org>drivers/misc/ad525x_dpot-i2c.c]] |
 +| spi bus support  | [[git.linux.org>drivers/misc/ad525x_dpot-spi.c]] |
 +| include | [[git.linux.org>drivers/misc/ad525x_dpot.h]] |
 +
 +
 +====== Example platform device initialization ======
 +
 +{{page>software/linux/docs/platform_and_bus_model#Platform Data&noheader&firstseconly&noeditbtn}}
 +
 +===== Example Platform / Board file (I2C Interface) =====
 +
 +{{page>software/linux/docs/platform_and_bus_model#Declaring I2C devices&firstseconly&noeditbtn}}
 +
 +<code C>
 +static struct i2c_board_info __initdata bfin_i2c_board_info[] = {
 +#if defined(CONFIG_AD525X_DPOT) || defined(CONFIG_AD525X_DPOT_MODULE)
 + {
 + I2C_BOARD_INFO("ad5245", 0x2c),
 + },
 + {
 + I2C_BOARD_INFO("ad5245", 0x2d),
 + },
 +#endif
 +}
 +</code>
 +
 +===== Example Platform / Board file (SPI Interface) =====
 +
 +{{page>software/linux/docs/platform_and_bus_model#Declaring SPI slave devices&firstseconly&noeditbtn}}
 +
 +<code C>
 +static struct spi_board_info bfin_spi_board_info[] __initdata = {
 +#if defined(CONFIG_AD525X_DPOT) || defined(CONFIG_AD525X_DPOT_MODULE)
 + {
 + .modalias = "ad5291",
 + .max_speed_hz = 5000000,     /* max spi clock (SCK) speed in HZ */
 + .bus_num = 0,
 + .chip_select = 1,
 + },
 +#endif
 +};
 +</code>
 +
 +<WRAP tip>
 +
 +__**Old Method**__
 +
 +<code C>
 +static struct spi_board_info bfin_spi_board_info[] __initdata = {
 +#if defined(CONFIG_AD525X_DPOT) || defined(CONFIG_AD525X_DPOT_MODULE)
 + {
 + .modalias = "ad_dpot",
 + .platform_data = "ad5291",
 + .max_speed_hz = 5000000,     /* max spi clock (SCK) speed in HZ */
 + .bus_num = 0,
 + .chip_select = 1,
 + },
 +#endif
 +};
 +</code>
 +</WRAP>
 +
 +
 +====== Adding Linux driver support ======
 +
 +Configure kernel with "make menuconfig" (alternatively use "make xconfig" or
 +"make qconfig")
 +
 +<WRAP round help>
 +The ad525x_dpot driver depends on **CONFIG_SPI** or **CONFIG_I2C**
 +</WRAP>
 +
 +<code>
 +Device Drivers  --->
 +  [*] Misc devices  --->
 +    <*>   Analog Devices Digital Potentiometers
 +    <*>     support I2C bus connection
 +    <*>     support SPI bus connection
 +</code>
 +
 +====== Hardware configuration ======
 +
 +{{:resources:tools-software:linux-drivers:misc:pmoddpot_lr.png?600|PmodDPOT, ADSP-BF537 EZKIZ}}
 +====== Driver testing ======
 +
 +Locate the device in your sysfs tree.  This is probably easiest by going into
 +the common i2c directory and locating the device by the i2c slave address.
 +
 +<xterm> 
 + # ls /sys/bus/i2c/devices/
 + 0-0022  0-0027  0-002f
 +</xterm> 
 +So assuming the device in question is on the first i2c bus and has the slave
 +address of 0x2f, we descend (unrelated sysfs entries have been trimmed).
 +
 +<xterm>  
 + # ls /sys/bus/i2c/devices/0-002f/
 + eeprom0 rdac0 tolerance0
 +</xterm>  
 +You can use simple reads/writes to access these files:
 + 
 +<xterm> 
 + # cd /sys/bus/i2c/devices/0-002f/
 + 
 + # cat eeprom0
 + 0
 + # echo 10 > eeprom0
 + # cat eeprom0
 + 10
 + 
 + # cat rdac0
 + 5
 + # echo 3 > rdac0
 + # cat rdac0
 + 3
 +</xterm> 
 +====== More Information ======
 +
  
resources/tools-software/linux-drivers/misc/dpot.txt · Last modified: 05 Jan 2021 15:57 by Ioana Chelaru

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