Invoke gcc compiler. -o means to generate files, and will be followed by the name of generated

file. fan.c is source program, and -lwiringPi means to use the wiringPi library in Raspberry Pi.

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Run program

./fan

The fan will start to rotate in 2s, and its speed will increase every second. When reaching to the

highest speed, it will run for two seconds and then stop, and so on.

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Codes Analysis

1. Init Raspberry Pi I2C configuration.

2. Control fan speed in loop. The fan speed level can be known from the protocol: 0x00: close;

0x01: full speed; 0x02: 20%speed; 0x03: 30%speed;....0x09: 90%speed.