Linux中的libiio编程实践

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开发板：Omapl138

AD模块：AD7606

1 交叉编译libiio

关于libiio的交叉编译，见《Linux中交叉编译libiio》。

2 简单实例

#include <iio.h>#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <string.h>/* * 功 能: 通道属性检索 * 参 数: chn —— AD 通道 *   attr —— 需要检索的属性 * 返 回: true  —— AD通道存在属性attr *   false —— AD通道不存在属性attr */static bool channel_has_attr(struct iio_channel *chn, const char *attr){unsigned int i, nb = iio_channel_get_attrs_count(chn);for (i = 0; i < nb; i++)// printf("channel attr = %s\n", iio_channel_get_attr(chn, i));if (!strcmp(attr, iio_channel_get_attr(chn, i)))return true;return false;}/* * 功 能: 获取通道chan的采样值 * 参 数: chn —— AD 通道 * 返 回: chn 通道的采样值 */static double get_channel_value(struct iio_channel *chn){char buf[1024];double val;if (channel_has_attr(chn, "processed")) {iio_channel_attr_read(chn, "processed", buf, sizeof(buf));val = strtod(buf, NULL);} else {iio_channel_attr_read(chn, "raw", buf, sizeof(buf));val = strtod(buf, NULL);if (channel_has_attr(chn, "offset")) {iio_channel_attr_read(chn, "offset", buf, sizeof(buf));val += strtod(buf, NULL);}if (channel_has_attr(chn, "scale")) {iio_channel_attr_read(chn, "scale", buf, sizeof(buf));val *= strtod(buf, NULL);}}val = val * 5 / 32768.0;return val;}int main(void){struct iio_context *ctx;unsigned int i, nb_devices;unsigned int nb_channels;double channel_value;struct iio_device *dev;struct iio_channel *chn;// create contextctx = iio_create_local_context();if ( !ctx) {printf("create context failed\n");exit(0);}// get device countnb_devices = iio_context_get_devices_count(ctx);// get device namedev = iio_context_get_device(ctx, 0);nb_channels = iio_device_get_channels_count(dev);chn = iio_device_get_channel(dev, 0);printf("channel_value:\n");for (i = 0; i < 100000; i++) {channel_value = get_channel_value(chn);printf("%.2f\n", channel_value);sleep(1);}iio_context_destroy(ctx);return 0;}

参考资料

[1]What is libiio?

[2]libiio_Main Page

[3]About libiio

[4]iio-trig-sysfs driver

[5]IIO Command Server

[6][RFC] LIBIIO

[7]libiio buffering

[8]How to Get Analog Input on the BeagleBone Black

[9]How to use the Linux Industrial IO (IIO) interface

[10]AM335x ADC Driver's Guide

[11]AD7606: Data capture by setting sampling frequency & buffer mode

[12]IIO, a new kernel subsystem

[13]Why this program can't receive the right data?

[14]linux-3.2.20/drivers/staging/iio/industrialio-buffer.c

[15]Linux Core ADC User's Guide

[16]am335x adc调试

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