git-svn-id: https://rt-thread.googlecode.com/svn/trunk@2160 bbd45198-f89e-11dd-88c7-29a3b14d5316
According to the Atmel official recommended, use GPIO instead of TWI for I2C communication git-svn-id: https://rt-thread.googlecode.com/svn/trunk@2129 bbd45198-f89e-11dd-88c7-29a3b14d5316