Quick for imx6ull development board c program call shell

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This chapter is about linux Under system environment linux-C call shell Command control GPIO Input and output steps .shell As Linux  The shell of the operating system , Provide users with an interface to use the operating system . It's a command language 、 Command interpreter and programming language , It interprets commands entered by the user and sends them to the kernel .

Use shell The command operates directly /sys/ Under the gpio node , First, in the imx6ull-14x14-evk.dts Comment out the device tree  LED And button function ,LED Pin for GPIO0_3,key Pin for GPIO1_18.

Pass in the program shell Command to read key values and control LED The lamp .

1. adopt popen perform shell command

popen and pclose The function is to create a pipeline , Used to connect to another process , Then read the output of that process or send input to it , The specific operation is fork A subprocess ,exec One shell Carry out orders .

2. Fill in shell command , Set pin status

3. control Led

Cross compilation arm-linux-gnueabihf-gcc -o led shellGpio.c , take led Copy the file to the development board .

Test can see that the light of the development board is flashing , The terminal has print information ：

4. Read the key value

Post compile testing ：

Good product recommendation - Fast for quality IMX6ULL Development board

Terminator information is open source , If you don't buy it, you can download software and hardware resources freely  

  You just need to focus on VX official account ： XunWei Electronics ,   reply ： The terminator , Free access to product information  

 i.MX6ULL Terminator manual download link  
https://pan.baidu.com/s/171NHz6_sVMGIQ3g7GcCqOQ   Extraction code ：n3og 

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https://space.bilibili.com/33785640

 i.MX6ULL Terminator development board Introduction  
https://www.bilibili.com/video/BV1aE411F7S9

 i.MX6ULL Terminator development board out of the box experience  
https://www.bilibili.com/video/BV1M7411m7wT

Linux-QT The tutorial is free to watch here , Xunwei is the first to provide 6ULL Of QT Video actual combat course , Try the fresh version ：

In this issue QT What knowledge will the video harvest ？
https://www.bilibili.com/video/BV1tp4y1i7EJ?p=1
P10 QT Serial port assistant for PC development （ On ）
https://www.bilibili.com/video/BV1tp4y1i7EJ?p=10
QT Network programming UDP signal communication
https://www.bilibili.com/video/BV1tp4y1i7EJ?p=14
QT Cross compilation of system transplantation QT Source code and touch source code
https://www.bilibili.com/video/BV1tp4y1i7EJ?p=17
QT Cross platform operation QT Program cross compiled to ARM Development board
https://www.bilibili.com/video/BV1tp4y1i7EJ?p=19
QT The use of cross platform operation QT Control the buzzer
https://www.bilibili.com/video/BV1tp4y1i7EJ?p=20
QT Cross platform operation QT Program compiled into mobile phone APP
https://www.bilibili.com/video/BV1tp4y1i7EJ?p=21
Copy a smart home interface （ On ）
https://www.bilibili.com/video/BV1tp4y1i7EJ?p=7
Copy a smart home interface （ Next ）
https://www.bilibili.com/video/BV1tp4y1i7EJ?p=9