I2C Timing Item

1. I2c timing protocol;
1) WRTIE:

In the case of writing, we need to use only one message;

-Start -|Addr+w| register| data| -stop-

2) READ:

when reading, we need two.

-Start -|Addr+w| register| -stop-
-Start -|Addr+r| data....| -stop-

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In the slave view

When slave recieved the Addr+w, Slave enter recieve interrupt.

When slave recieved the Addr+r, Slave enter transmit interrupt.

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I2cdetect 實際上是調用了SMBBUS 的接口：
它事實上等價與 smbus_read_byte()（沒有指定要讀的register）; 只是並不關心讀取的那一byte 是什麼， 只要有迴應數據即可！

-Start -|Addr+r| 1 byte data| -stop-

I2c 設備是通過i2c_detect ()函數來完成的！只有被detect 到的device 才能被註冊！