Adding I2C Interface test with Arduino

[TheoHollender]

We want to add a test for the I2C interface that checks whether all the drivers work using an arduino.

[TheoHollender]

The test is already ready and works in the following way :

The Arduino works as an I2C Slave on address 0x42, and the following protocol is used :

• The Raspberry Pi sends on register 1 the "Hello, World !\0" string without using the write function (using writeDevice by putting register in front of the string)
• If the received string is correct, the Arduino sends "Hello, RPI !\0" back and the Raspberry Pi verifies it is present (testing readDevice).
• Then the Raspberry Pi writes 256 times a byte (all distinct) in register 0 (using write) and expects the arduino to send it back.
• Finally, the raspberry pi reads 10.000 randoms bytes (<= 165) from register 2 (using read), and the raspberry pi checks the fact that bytes are <= 165 and that the entropy is correct.

Some information about the testing :

• The arduino has a delay of about 350 microseconds to avoid a input / output error when ioctl (i suspect that the arduino code is too slow otherwise and gets interrupted too fast)