Support » Pololu Simple Motor Controller G2 User’s Guide » 4. Connecting your motor controller »
4.4. Connecting an I²C device
The SCL and SDA pins on the Simple Motor Controller G2 can be used to communicate with microcontrollers that support I²C. The Simple Motor Controller G2 acts as an I²C slave and accepts commands from the master device. The Simple Motor Controller G2 is compatible with I²C bus voltage levels from 1.8 V to 5 V.
Note that I²C is not enabled by default. You will need to check the “Enable I2C” checkbox in the “Input settings” tab of the Simple Motor Control Center G2 software, and then click “Apply settings” to enable it.
You will need to connect the SCL pin of your master device to the SCL pin of the Simple Motor Controller G2, and connect the SDA pin of the master device to the SDA pin of the Simple Motor Controller G2. (On the 18v25 and 24v19, you can use either of the two SCL pins.) To control multiple devices, connect all the SCL pins together and connect all the SDA pins together.
The SDA and SCL pins do not have pull-up resistors enabled, so you should make sure that your master device has pull-ups on both lines, or add external ones yourself. If you find that you need to add pull-up resistors, a resistance of 10 kΩ is a good place to start, but you might need to adjust the resistance depending on how much capacitance is on the bus and how fast you want to run the clock.