Required Hardware
The MCP23017 provides an easy, cheap and effective solution by providing an extra 16 lines of I/O which can be written to and read from through the I2C interface that most microcontrollers provide.
Wiring
To wire your MCP23017 Expander to your Arduino, connect the following pins:
- Pin 15 (A0) –> Arduino Ground
- Pin 16 (A1) –> Arduino Ground
- Pin 17 (A2) –> Arduino Ground
- Pin 18 (Reset) –> Arduino +5V
- Pin 19 (Int B) –> N/C
- Pin 20 (Int A) –> N/C
- Pin 21 – 28 –> Button Pin (-)
- Pin 1 – 8 –> Led Pin(+) via 470ohm Resisotr
- Pin 9 (Vdd) –> Arduino +5V
- Pin 10 (Vss) –> Arduino Ground
- Pin 11 –> N/C
- Pin 12 (Scl) –> Arduino Pin A5
- Pin 13 (Sda) –> Arduino Pin A4
- Pin 14 –> N/C
Don’t forget to wire all the Ground Pins of each Led to the Arduino Ground. Also connect all the tact pins(-) via 10Kohm Resistor to the Ground and all the tact pins(+) to the +5V.
Recommended Software
- none
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