電子發(fā)燒友App
創(chuàng)作
發(fā)文章
發(fā)帖 
提問 
發(fā)資料
發(fā)視頻資料介紹
Table of Contents
Digital Potentiometer Linux Driver
Supported Devices
Reference Circuits
Evaluation Boards
- PMOD-DPOT
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
Files
| Function | File |
|---|---|
| driver | drivers/misc/ad525x_dpot.c |
| i2c bus support | drivers/misc/ad525x_dpot-i2c.c |
| spi bus support | drivers/misc/ad525x_dpot-spi.c |
| include | drivers/misc/ad525x_dpot.h |
Example platform device initialization
For compile time configuration, it’s common Linux practice to keep board- and application-specific configuration out of the main driver file, instead putting it into the board support file.
For devices on custom boards, as typical of embedded and SoC-(system-on-chip) based hardware, Linux uses platform_data to point to board-specific structures describing devices and how they are connected to the SoC. This can include available ports, chip variants, preferred modes, default initialization, additional pin roles, and so on. This shrinks the board-support packages (BSPs) and minimizes board and application specific #ifdefs in drivers.
Example Platform / Board file (I2C Interface)
Declaring I2C devices
Unlike PCI or USB devices, I2C devices are not enumerated at the hardware level. Instead, the software must know which devices are connected on each I2C bus segment, and what address these devices are using. For this reason, the kernel code must instantiate I2C devices explicitly. There are different ways to achieve this, depending on the context and requirements. However the most common method is to declare the I2C devices by bus number.
This method is appropriate when the I2C bus is a system bus, as in many embedded systems, wherein each I2C bus has a number which is known in advance. It is thus possible to pre-declare the I2C devices that inhabit this bus. This is done with an array of struct i2c_board_info, which is registered by calling i2c_register_board_info().
So, to enable such a driver one need only edit the board support file by adding an appropriate entry to i2c_board_info.
For more information see: Documentation/i2c/instantiating-devices
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 }
Example Platform / Board file (SPI Interface)
Declaring SPI slave devices
Unlike PCI or USB devices, SPI devices are not enumerated at the hardware level. Instead, the software must know which devices are connected on each SPI bus segment, and what slave selects these devices are using. For this reason, the kernel code must instantiate SPI devices explicitly. The most common method is to declare the SPI devices by bus number.
This method is appropriate when the SPI bus is a system bus, as in many embedded systems, wherein each SPI bus has a number which is known in advance. It is thus possible to pre-declare the SPI devices that inhabit this bus. This is done with an array of struct spi_board_info, which is registered by calling spi_register_board_info().
For more information see: Documentation/spi/spi-summary
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 };
Old Method
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 };
Adding Linux driver support
Configure kernel with “make menuconfig” (alternatively use “make xconfig” or “make qconfig”)
The ad525x_dpot driver depends on CONFIG_SPI or CONFIG_I2C
Device Drivers --->
[*] Misc devices --->
<*> Analog Devices Digital Potentiometers
<*> support I2C bus connection
<*> support SPI bus connection
Hardware configuration
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.
# ls /sys/bus/i2c/devices/ 0-0022 0-0027 0-002fSo 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).
# ls /sys/bus/i2c/devices/0-002f/ eeprom0 rdac0 tolerance0You can use simple reads/writes to access these files:
# 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
More Information
- 數(shù)字電位器X9C103的測試程序代碼下載 58次下載
- AD9834 IIO直接數(shù)字合成Linux驅(qū)動(dòng)程序
- AD9832 IIO直接數(shù)字合成Linux驅(qū)動(dòng)程序
- 數(shù)字電位器的PCB原理圖免費(fèi)下載 30次下載
- DS1666數(shù)字電位器的中文資料說明 25次下載
- STM32F103數(shù)字電位器X9C103的驅(qū)動(dòng)程序免費(fèi)下載 190次下載
- 優(yōu)化數(shù)字電位器電路設(shè)計(jì)方案 12次下載
- Linux驅(qū)動(dòng)程序缺陷檢測研究 9次下載
- Linux系統(tǒng)網(wǎng)絡(luò)驅(qū)動(dòng)程序的編寫 0次下載
- 第9章 Linux驅(qū)動(dòng)程序設(shè)計(jì) 3次下載
- 理解和應(yīng)用數(shù)字電位器
- DAC與數(shù)字電位器
- 數(shù)字電位器的應(yīng)用
- 理解和應(yīng)用數(shù)字電位器
- 從機(jī)械式電位器升級到數(shù)字電位器
- 用線性數(shù)字電位器實(shí)現(xiàn)對數(shù)調(diào)節(jié) 1557次閱讀
- 數(shù)字控制電位器和電阻器與激光驅(qū)動(dòng)器接口 809次閱讀
- 數(shù)字電位器取代機(jī)械電位器 2492次閱讀
- AD8400系列數(shù)字電位器的驅(qū)動(dòng)設(shè)計(jì)與實(shí)現(xiàn) 3713次閱讀
- AD527x系列數(shù)字電位器的驅(qū)動(dòng)設(shè)計(jì)與實(shí)現(xiàn) 2233次閱讀
- 米爾科技LINUX設(shè)備驅(qū)動(dòng)程序教程 2105次閱讀
- 數(shù)字電位器AD5160測試程序 2.4w次閱讀
- 如何理解數(shù)字電位器 9505次閱讀
- 如何制作數(shù)字電位器_數(shù)字電位器制作方法 2.1w次閱讀
- 常用數(shù)字電位器芯片有哪些 11.3w次閱讀
- 數(shù)字電位器工作原理詳解_數(shù)字電位器應(yīng)用_數(shù)字電位器選型指南 5.9w次閱讀
- 數(shù)字電位器控制原理圖 3.5w次閱讀
- 數(shù)字電位器應(yīng)用實(shí)例_數(shù)字電位器四大應(yīng)用電路 4.6w次閱讀
- 數(shù)字電位器怎么選型_數(shù)字電位器選型指南 9628次閱讀
- 數(shù)字電位器串口設(shè)計(jì)與仿真 1835次閱讀
上傳資料賺積分下載排行
本周
- 1AN-1267: 使用ADSP-CM408F ADC控制器的電機(jī)控制反饋采樣時(shí)序
- 1.41MB | 3次下載 | 免費(fèi)
- 2AN158 GD32VW553 Wi-Fi開發(fā)指南
- 1.51MB | 2次下載 | 免費(fèi)
- 3AN148 GD32VW553射頻硬件開發(fā)指南
- 2.07MB | 1次下載 | 免費(fèi)
- 4AN-1154: 采用恒定負(fù)滲漏電流優(yōu)化ADF4157和ADF4158 PLL的相位噪聲和雜散性能
- 199.28KB | 次下載 | 免費(fèi)
- 5AN-960: RS-485/RS-422電路實(shí)施指南
- 380.8KB | 次下載 | 免費(fèi)
- 6EE-249：使用VisualDSP在ADSP-218x DSP上實(shí)現(xiàn)軟件疊加
- 60.02KB | 次下載 | 免費(fèi)
- 7AN-1111: 使用ADuCM360/ADuCM361時(shí)的降低功耗選項(xiàng)
- 306.09KB | 次下載 | 免費(fèi)
- 8AN-904: ADuC7028評估板參考指南
- 815.82KB | 次下載 | 免費(fèi)
本月
- 1ADI高性能電源管理解決方案
- 2.43 MB | 450次下載 | 免費(fèi)
- 2免費(fèi)開源CC3D飛控資料（電路圖&PCB源文件、BOM、
- 5.67 MB | 138次下載 | 1 積分
- 3基于STM32單片機(jī)智能手環(huán)心率計(jì)步器體溫顯示設(shè)計(jì)
- 0.10 MB | 130次下載 | 免費(fèi)
- 4使用單片機(jī)實(shí)現(xiàn)七人表決器的程序和仿真資料免費(fèi)下載
- 2.96 MB | 44次下載 | 免費(fèi)
- 5美的電磁爐維修手冊大全
- 1.56 MB | 24次下載 | 5 積分
- 6如何正確測試電源的紋波
- 0.36 MB | 18次下載 | 免費(fèi)
- 7感應(yīng)筆電路圖
- 0.06 MB | 10次下載 | 免費(fèi)
- 8萬用表UT58A原理圖
- 0.09 MB | 9次下載 | 5 積分
總榜
- 1matlab軟件下載入口
- 未知 | 935121次下載 | 10 積分
- 2開源硬件-PMP21529.1-4 開關(guān)降壓/升壓雙向直流/直流轉(zhuǎn)換器 PCB layout 設(shè)計(jì)
- 1.48MB | 420062次下載 | 10 積分
- 3Altium DXP2002下載入口
- 未知 | 233088次下載 | 10 積分
- 4電路仿真軟件multisim 10.0免費(fèi)下載
- 340992 | 191367次下載 | 10 積分
- 5十天學(xué)會AVR單片機(jī)與C語言視頻教程 下載
- 158M | 183335次下載 | 10 積分
- 6labview8.5下載
- 未知 | 81581次下載 | 10 積分
- 7Keil工具M(jìn)DK-Arm免費(fèi)下載
- 0.02 MB | 73810次下載 | 10 積分
- 8LabVIEW 8.6下載
- 未知 | 65988次下載 | 10 積分
工商網(wǎng)監(jiān)
評論