Expander - MCP23016
I2C Expander - I2C - MCP23016
Fig. 1 I2C expander
Description:
This board is an 2 x 8 bits ports expander connected with an I2C interface. It is based around a MCP23016 chip.
It connects to a host with an I2C bus. It can generate interrupt on pin change.
The board can be powered from 2 to 5V.
Specifications:
Input voltage 2 to 5V
InterfaceI2C
Ports2 x 8 bits
Schematic:
The SDA and SCK I2C lines are pulled high by R2 and R3, while R8 and R9 protects the lines. R5 to R7 pull address line A0 to A2 low. The lines can be pulled high by SW1, and can be used to set the I2C slave address of the board.
C2 filters the power supply. R1 pulls the Int signal high, because the ouput of the MCP23016 is open drain. The Int signal can be connected to the I2C bus with SW1.
R4/C1 make the chip oscillator run.
The I2C connector K1 and K2 allow the board to be connected to an I2C bus in a chain. K3 and K4 provides the interface to ports 0 and 1 of the expander chip.
R10 is here to have an easy Gnd point to connect a test instrument.
Fig. 2 I2C expander schematic
Construction:
The PCB fits on a small single sided board. All components are on the top side.
Fig. 3 I2C expander layout
Start with the 3 wire links (one beside K3, one under U1 and 1 under SW1), then the lowest components, and continue with the higher ones.
R10 is made up of a piece of resistor's lead. It's here to easily attach a clip from a test instrument or have a Gnd test point.
Pads 1 to 4 can be drilled to 3mm to fix the board, or put spacers.
| I2C Eeprom Component list |
|---|
| C1: 33 pF C2: 100 nF R1, R5, R6, R7: 100 K R2, R3: 22K R4: 3.9 K R5, R6: 22 K R8, R9: 220 R10: resistor's lead U1: MCP23016-IP (DIL package) SW1: micro-switches 1x4 K1, K2: Connector AMP MT 5pins male K3, K4: Connector AMP MT 10pins male |
How to use / Testing:
To check the board, you need a processor board running the I2C extension tutorial. Just make sure you set right I2C slave address with SW1.
Files and links:
Eagle PCB and schematics files for I2C expander.PDFs of PCB, layout and schematics of I2C expander.
PIC Tutorials for I2C extension.
Microchip MCP23016 IO expander.