资料介绍
Table of Contents
AD5791 IIO DAC Linux Driver
Supported Devices
Reference Circuits
Evaluation Boards
Description
This is a Linux industrial I/O (IIO) subsystem driver, targeting single-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 IIO for more information.
Source Code
Status
Files
Function | File |
---|---|
driver | drivers/iio/dac/ad5791.c |
include | drivers/iio/dac/ad5791.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.
The reference voltage may vary between boards and models. The platform_data for the device's “struct device” holds this information.
/** * struct ad5791_platform_data - platform specific information * @vref_pos_mv: Vdd Positive Analog Supply Volatge (mV) * @vref_neg_mv: Vdd Negative Analog Supply Volatge (mV) * @use_rbuf_gain2: ext. amplifier connected in gain of two configuration */ struct ad5791_platform_data { u16 vref_pos_mv; u16 vref_neg_mv; bool use_rbuf_gain2; };
This driver supports also an alternative way of specifying the reference voltage, by using the Linux regulator framework.
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)
#if defined(CONFIG_REGULATOR_FIXED_VOLTAGE) || defined(CONFIG_REGULATOR_FIXED_VOLTAGE_MODULE) static struct regulator_consumer_supply ad5791_consumer_supplies_vdd[] = { REGULATOR_SUPPLY("vdd", "spi0.3"), }; static struct regulator_init_data stamp_avdd_reg_init_data = { .constraints = { .name = "10V0", .valid_ops_mask = REGULATOR_CHANGE_STATUS, }, .consumer_supplies = ad5791_consumer_supplies_vdd, .num_consumer_supplies = ARRAY_SIZE(ad5791_consumer_supplies_vdd), }; static struct fixed_voltage_config stamp_vdd_pdata = { .supply_name = "board+10V0", .microvolts = 10000000, .gpio = -EINVAL, .enabled_at_boot = 0, .init_data = &stamp_avdd_reg_init_data, }; static struct platform_device brd_voltage_regulator_vdd = { .name = "reg-fixed-voltage", .id = 0, .num_resources = 0, .dev = { .platform_data = &stamp_vdd_pdata, }, }; static struct regulator_consumer_supply ad5791_consumer_supplies_vss[] = { REGULATOR_SUPPLY("vss", "spi0.3"), }; static struct regulator_init_data stamp_avss_reg_init_data = { .constraints = { .name = "-10V0", .valid_ops_mask = REGULATOR_CHANGE_STATUS, }, .consumer_supplies = ad5791_consumer_supplies_vss, .num_consumer_supplies = ARRAY_SIZE(ad5791_consumer_supplies_vss), }; static struct fixed_voltage_config stamp_vss_pdata = { .supply_name = "board-10V0", .microvolts = 10000000, .gpio = -EINVAL, .enabled_at_boot = 0, .init_data = &stamp_avss_reg_init_data, }; static struct platform_device brd_voltage_regulator_vss = { .name = "reg-fixed-voltage", .id = 1, .num_resources = 0, .dev = { .platform_data = &stamp_vss_pdata, }, }; #endif
static struct platform_device *board_devices[] __initdata = { #if defined(CONFIG_REGULATOR_FIXED_VOLTAGE) || defined(CONFIG_REGULATOR_FIXED_VOLTAGE_MODULE) &brd_voltage_regulator_vss, &brd_voltage_regulator_vdd, #endif };
static int __init board_init(void) { [--snip--] platform_add_devices(board_devices, ARRAY_SIZE(board_devices)); [--snip--] return 0; } arch_initcall(board_init);
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
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.
static struct spi_board_info board_spi_board_info[] __initdata = { #if defined(CONFIG_AD5791) || / defined(CONFIG_AD5791 _MODULE) { /* the modalias must be the same as spi device driver name */ .modalias = "ad5791", /* 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 */ .platform_data = &ad5791_pdata, .mode = SPI_MODE_3, }, #endif };
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);
Adding Linux driver support
Configure kernel with “make menuconfig” (alternatively use “make xconfig” or “make qconfig”)
The AD5791 Driver depends on CONFIG_SPI
Linux Kernel Configuration Device Drivers ---> ... <*> Industrial I/O support ---> --- Industrial I/O support ... Digital to analog converters ---> ... <*> Analog Devices AD5760/AD5780/AD5781/AD5790/AD5791 DAC SPI driver ... ... ...
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.
This specifies any shell prompt running on the target
root:/> cd /sys/bus/iio/devices/ root:/sys/bus/iio/devices> ls device0 root:/sys/bus/iio/devices> cd device0 root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> ls -l drwxr-xr-x 2 root root 0 Jan 4 12:28 . drwxr-xr-x 3 root root 0 Jan 4 12:28 .. -r--r--r-- 1 root root 4096 Jan 4 12:28 name -rw-r--r-- 1 root root 4096 Jan 4 12:29 out_voltage0_powerdown -rw-r--r-- 1 root root 4096 Jan 4 12:30 out_voltage0_raw -rw-r--r-- 1 root root 4096 Jan 4 12:28 out_voltage_powerdown_mode -r--r--r-- 1 root root 4096 Jan 4 12:28 out_voltage_powerdown_mode_available -r--r--r-- 1 root root 4096 Jan 4 12:28 out_voltage_scale lrwxrwxrwx 1 root root 0 Jan 4 12:28 subsystem -> ../../../../../bus/iio -rw-r--r-- 1 root root 4096 Jan 4 12:28 uevent
Show device name
This specifies any shell prompt running on the target
root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> cat name ad5791
Show scale
Description:
scale to be applied to out_voltage0_raw in order to obtain the measured voltage in millivolts.
This specifies any shell prompt running on the target
root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> cat out_voltage_scale 0.019
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.
This specifies any shell prompt running on the target
root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> echo 131579 > out_voltage0_raw
U = out_voltage0_raw * out_voltage_scale = 131579 * 0.019 = 2500.001 mV
This specifies any shell prompt running on the target
root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> echo -131579 > out_voltage0_raw
U = out_voltage0_raw * out_voltage_scale = -131579 * 0.019 = -2500.001 mV
List available power down modes
/sys/bus/iio/devices/iio:deviceX/out_voltage_powerdown_mode_available
Description:
Lists all available output power down modes.
This specifies any shell prompt running on the target
root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> cat out_voltage_powerdown_mode_available 6kohm_to_gnd three_state
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
6kohm_to_gnd | connected to ground via an 6kOhm resistor |
three_state | left floating |
For a list of available output power down options read out_voltage_powerdown_mode_available.
This specifies any shell prompt running on the target
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
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.
This specifies any shell prompt running on the target
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
More Information
- IIO mailing list: linux [dash] iio [at] vger [dot] kernel [dot] org
- AD5790评估软件 5次下载
- AD5790 IBIS型号 8次下载
- AD5504 IO高体积ADC Linux漂流器 7次下载
- AD1836声音Linux漂流器 5次下载
- AD9523低速克洛克发电机Linux漂流器 1次下载
- 基于Nios驱动的AD5790 BeMicro FPGA方案 3次下载
- AD7298 IIO多通道ADC Linux漂流器 9次下载
- SM2602声音Linux漂流器 2次下载
- ADAU1977声音Linux漂流器 1次下载
- AD5760/AD5780/AD5790快速入门指南 7次下载
- AD7793 ILO低能西格玛三角洲Linux漂流器 3次下载
- SM2518声音Linux漂流器 13次下载
- AD5790 FMC-SDP转接器和评估板/Xilinx KC705参考设计 14次下载
- AD5790:可供系统立即使用的20位、±2LSB INL电压输出DAC 5次下载
- 系统准备20位电压输出数模转换器ad5790数据表 5次下载
- linux和windows的区别 linux系统一般用来干嘛 252次阅读
- 如何在zcu102板卡上创建pipeline呢? 172次阅读
- 5G新开站点D4频段干扰案例分享 655次阅读
- Linux 下的make 工具和 Makefile 536次阅读
- linux中管道符的使用 3233次阅读
- GNU/Linux和Linux的区别在哪? 1056次阅读
- 监控你的站点访问是否正常 513次阅读
- IEEE 802.11ax站点上行链路准确性测试方案 2392次阅读
- Linux教程之Linux常用命令大全 5367次阅读
- Linux学习书籍推荐Linux就该这么学 4566次阅读
- 嵌入式Linux系统开发入门基础 1698次阅读
- Linux终端测试网速的方法 6765次阅读
- Linux服务器加固的基本步骤详解 4218次阅读
- 基于zynq的Linux根文件系统生成 5020次阅读
- 微波解决LTE回传站点光纤短缺问题 1216次阅读
下载排行
本周
- 1电子电路原理第七版PDF电子教材免费下载
- 0.00 MB | 1491次下载 | 免费
- 2单片机典型实例介绍
- 18.19 MB | 95次下载 | 1 积分
- 3S7-200PLC编程实例详细资料
- 1.17 MB | 27次下载 | 1 积分
- 4笔记本电脑主板的元件识别和讲解说明
- 4.28 MB | 18次下载 | 4 积分
- 5开关电源原理及各功能电路详解
- 0.38 MB | 11次下载 | 免费
- 6100W短波放大电路图
- 0.05 MB | 4次下载 | 3 积分
- 7基于单片机和 SG3525的程控开关电源设计
- 0.23 MB | 4次下载 | 免费
- 8基于AT89C2051/4051单片机编程器的实验
- 0.11 MB | 4次下载 | 免费
本月
- 1OrCAD10.5下载OrCAD10.5中文版软件
- 0.00 MB | 234313次下载 | 免费
- 2PADS 9.0 2009最新版 -下载
- 0.00 MB | 66304次下载 | 免费
- 3protel99下载protel99软件下载(中文版)
- 0.00 MB | 51209次下载 | 免费
- 4LabView 8.0 专业版下载 (3CD完整版)
- 0.00 MB | 51043次下载 | 免费
- 5555集成电路应用800例(新编版)
- 0.00 MB | 33562次下载 | 免费
- 6接口电路图大全
- 未知 | 30320次下载 | 免费
- 7Multisim 10下载Multisim 10 中文版
- 0.00 MB | 28588次下载 | 免费
- 8开关电源设计实例指南
- 未知 | 21539次下载 | 免费
总榜
- 1matlab软件下载入口
- 未知 | 935053次下载 | 免费
- 2protel99se软件下载(可英文版转中文版)
- 78.1 MB | 537793次下载 | 免费
- 3MATLAB 7.1 下载 (含软件介绍)
- 未知 | 420026次下载 | 免费
- 4OrCAD10.5下载OrCAD10.5中文版软件
- 0.00 MB | 234313次下载 | 免费
- 5Altium DXP2002下载入口
- 未知 | 233046次下载 | 免费
- 6电路仿真软件multisim 10.0免费下载
- 340992 | 191183次下载 | 免费
- 7十天学会AVR单片机与C语言视频教程 下载
- 158M | 183277次下载 | 免费
- 8proe5.0野火版下载(中文版免费下载)
- 未知 | 138039次下载 | 免费
评论
查看更多