嵌入式 ARM 平台 libsoc 开发示例

By Toradex秦海

1).简介

在之前的一篇文章中已经介绍过如何基于嵌入式Linux部署libsoc支持，本文就继续基于NXP IMX6平台演示基于libsoc分别对GPIO，I2C，PWM以及SPI进行开发示例。

本文所演示的ARM平台同样来自于Toradex基于NXP iMX6 ARM处理器的Apalis iMX6 ARM嵌入式平台。

2.准备

a). Apalis iMX6Q ARM核心版配合Apalis Evaluation Board载板，连接调试串口UART1（载板X29）到开发主机方便调试。更多关于Apalis iMX6配合Apalis Evaluation Board载板的说明请参考Datasheet和开发上手指南。

b). Apalis iMX6Q ARM核心版配合Ixora载板，连接调试串口UART1（载板X22）到开发主机方便调试。更多关于Apalis iMX6配合Ixora载板的说明请参考Datasheet和开发上手指南。

c). Apalis iMX6Q安装Toradex Linux BSP V2.8b5，系统中已经默认包含了本文测试所需要的libsoc相关库支持，详细安装方法请参考这里，编译libsoc相关demo所需要的SDK配置请参考简介中提到的之前文章说明，本文不再赘述。

3). GPIO测试示例

a).基于Apalis Evaluation Board测试，硬件连接配置如下，基于C代码的GPIO测试请参考这里，本文是基于libsoc来重新测试。

X4 GPIO05 <-> X34 SW5

X4 GPIO06 <-> X34 LED1

b).源代码请参考如下，实现功能就是按键交替点亮和关闭LED灯。

https://github.com/simonqin09/libsoc-examples/blob/master/gpiotest/gpiointtest.c

c). Makefile请参考如下，直接下载的libsoc官方示例里面包含的Makefile需要进行一些修改，这里也将修改的patch附上。

./ Makefile

https://github.com/simonqin09/libsoc-examples/blob/master/gpiotest/Makefile

./ Patch file

https://github.com/simonqin09/libsoc-examples/blob/master/gpiotest/libsoc-examples_Makefile.patch

d).测试运行结果如下：

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root@apalis-imx6:~# ./gpiointtest

Waiting for interrupt. Press 'q' and 'Enter' at any time to exit

LED turns on

Interrupt occurred 1 times

LED turns off

Interrupt occurred 2 times

…

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4). PWM测试示例

a).基于Apalis Evaluation Board测试，硬件连接配置如下,基于C代码的PWM测试请参考这里，本文是基于libsoc来重新测试。

X4 GPIO05 <-> X34 SW5

X4 PWM1 <-> X34 LED1

b).源代码和Makefile请参考如下，实现功能就是程序运行后，PWM以50%占空比输出，通过按键让PWM输出占空比按照50%，75%，25%交替调整。

https://github.com/simonqin09/libsoc-examples/blob/master/pwmtest/pwmtest.c

https://github.com/simonqin09/libsoc-examples/blob/master/pwmtest/Makefile

PWM2和PWM3也都可以测试，只是PWM3默认被ov5640_mipi驱动占用，需要修改device tree释放。

d).测试运行结果如下：

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root@apalis-imx6:~# ./pwmtest

Waiting for interrupt. Press 'q' and 'Enter' at any time to exit

Interrupt occurred 1 times

PWM Duty set to 75%

Interrupt occurred 2 times

PWM Duty set to 25%

Interrupt occurred 3 times

PWM Duty set to 50%

Interrupt occurred 4 times

PWM Duty set to 75%

…

-----------------------

5). I2C测试示例

a).基于Ixora载板测试，针对载板上面连接到i2c-1的总线上面的EEPROM进行读写，基于C代码的详细测试文档可以参考这里，本文重新基于libsoc代码进行测试。

b).源代码和Makefile请参考如下，实现功能就是程序运行后，针对指定的page号码写入数据，然后再读取后验证是否读写一致。

I2ctest.c - https://github.com/simonqin09/libsoc-examples/blob/master/i2ctest/i2ctest.c

eeprom.c - https://github.com/simonqin09/libsoc-examples/blob/master/i2ctest/eeprom.c

eeprom.h - https://github.com/simonqin09/libsoc-examples/blob/master/i2ctest/eeprom.h

Makefile - https://github.com/simonqin09/libsoc-examples/blob/master/i2ctest/Makefile

d).测试运行结果如下：

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root@apalis-imx6:~# ./i2ctest 15

Writing to page starting at byte address: 0xf0

Waiting for data to be written

libsoc-i2c-debug: No such device or address

Waiting...

libsoc-i2c-debug: No such device or address

Waiting...

libsoc-i2c-debug: No such device or address

Waiting...

libsoc-i2c-debug: No such device or address

Waiting...

Data sucessfully written!

Reading page starting at byte address: 0xf0

data_write[0] = 0xf0 : data_read[0] = 0xf0 : Correct

data_write[1] = 0xf1 : data_read[1] = 0xf1 : Correct

data_write[2] = 0xf2 : data_read[2] = 0xf2 : Correct

data_write[3] = 0xf3 : data_read[3] = 0xf3 : Correct

data_write[4] = 0xf4 : data_read[4] = 0xf4 : Correct

data_write[5] = 0xf5 : data_read[5] = 0xf5 : Correct

data_write[6] = 0xf6 : data_read[6] = 0xf6 : Correct

data_write[7] = 0xf7 : data_read[7] = 0xf7 : Correct

data_write[8] = 0xf8 : data_read[8] = 0xf8 : Correct

data_write[9] = 0xf9 : data_read[9] = 0xf9 : Correct

data_write[10] = 0xfa : data_read[10] = 0xfa : Correct

data_write[11] = 0xfb : data_read[11] = 0xfb : Correct

data_write[12] = 0xfc : data_read[12] = 0xfc : Correct

data_write[13] = 0xfd : data_read[13] = 0xfd : Correct

data_write[14] = 0xfe : data_read[14] = 0xfe : Correct

data_write[15] = 0xff : data_read[15] = 0xff : Correct

-----------------------

6). SPI Master测试示例

a).基于Apalis Evaluation Board测试，需要配合Toradex另外一个基于NXP iMX7的平台作为SPI slave进行共同测试，关于硬件连接和SPI slave的配制和相关代码请参考下面文章，本文是基于libsoc来测试SPI Master端。

https://www.toradex.com/zh-cn/blog/nxp-imx7-m4-he-xin-spi-slave-ce-shi

b).源代码和Makefile请参考如下，实现功能就是程序运行后，通过Apalis iMX6 SPI0.0向SPI slave写入一组随机数据，然后再次通讯读出刚才写入的数据后确认读写是否一致。

spitest.c - https://github.com/simonqin09/libsoc-examples/blob/master/spitest/spitest.c

Makefile - https://github.com/simonqin09/libsoc-examples/blob/master/spitest/Makefile

d).测试运行结果如下：

-----------------------

root@apalis-imx6:~# ./spitest

Start to transfer!

data_send[0] = 0xca : data_read[0] = 0xca : Correct

data_send[1] = 0x03 : data_read[1] = 0x03 : Correct

data_send[2] = 0x01 : data_read[2] = 0x01 : Correct

data_send[3] = 0x56 : data_read[3] = 0x56 : Correct

data_send[4] = 0xb2 : data_read[4] = 0xb2 : Correct

data_send[5] = 0x64 : data_read[5] = 0x64 : Correct

data_send[6] = 0xf9 : data_read[6] = 0xf9 : Correct

data_send[7] = 0x34 : data_read[7] = 0x34 : Correct

data_send[8] = 0x91 : data_read[8] = 0x91 : Correct

data_send[9] = 0x84 : data_read[9] = 0x84 : Correct

data_send[10] = 0x19 : data_read[10] = 0x19 : Correct

data_send[11] = 0x0c : data_read[11] = 0x0c : Correct

data_send[12] = 0xb1 : data_read[12] = 0xb1 : Correct

data_send[13] = 0xd3 : data_read[13] = 0xd3 : Correct

data_send[14] = 0x1f : data_read[14] = 0x1f : Correct

data_send[15] = 0xf4 : data_read[15] = 0xf4 : Correct

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7).总结

如上述示例，通过基于iMX6测试了GPIO，I2C，PWM和SPI接口，对比C代码，libsoc使用和配置起来更方便简洁。