Going by that comment, and without having to go into the datasheet (although I suggest that you do if you want to understand what those lines mean), it appears that the Arduino Mega (16 MHz) defaults to 100 kHz I2C clock. Following the formula given, change the value of TWI_FREQ to achieve a desired I2C clock frequency. However, after reading the datasheet of the Atmega, it appears to me that the fastest you can get. Take a look at the section 24.5.2 Bit Rate Generator Unit to confirm this. If you define 'High Speed' to be 3.4 MHz I2C, then the answer appears to be no, you can't achieve that with your current hardware, but you should be able to get something faster than the default 100 kHz if you really want to.ĮDIT: It may be possible to achieve 1 MHz if I'm reading the datasheet correctly.

Formula used from the datasheet: SCL = (F_CPU)/(16 + 2*TWBR*4^TWPS) The disclaimer below still stands :pĭisclaimer: I just took a quick glance at the docs to come up with the above, it's totally possible that I missed something.

Wire library i2c