ZIO, Motherboard User Manual
Rev. 2.0
Zilogic Systems
Page 11
2. I²C Port
Connecting 5V I²C devices.
Since the I²C signal are pulled up to 5V, 5V I²C devices can be directly
connected to the I²C port.
Connecting 3.3V I²C devices with 5V tolerance.
Any 3.3V I²C device with 5V tolerance can be
directly connected to the I²C port. The device can be powered from an external 3.3V supply, or the
3.3V supply can be generated from the
+5V Power
using a regulator. An example circuit with the
commonly available LM1117-3.3 regulator is shown below.
IO Expander.
Additional digital inputs and outputs, if required, can be obtained using a I²C IO
expander. The PCA8574 provides 8 digital I/O lines, and PCA8578 provides 16 digital I/O lines. An
example circuit using the PCA8574, with I²C device address set to
0x20
, is shown below.
