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//Copyright (c) 2012, Adafruit Industries
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#include <Wire.h>
#include "Adafruit_MCP23017.h"
// Basic pin reading and pullup test for the MCP23017 I/O expander
// public domain!
// Connect pin #12 of the expander to Analog 5 (i2c clock)
// Connect pin #13 of the expander to Analog 4 (i2c data)
// Connect pins #15, 16 and 17 of the expander to ground (address selection)
// Connect pin #9 of the expander to 5V (power)
// Connect pin #10 of the expander to ground (common ground)
// Connect pin #18 through a ~10kohm resistor to 5V (reset pin, active low)
// Input #0 is on pin 21 so connect a button or switch from there to ground
Adafruit_MCP23017 mcp;
void setup() {
mcp.begin(); // use default address 0
mcp.pinMode(0, INPUT);
mcp.pullUp(0, HIGH); // turn on a 100K pullup internally
pinMode(13, OUTPUT); // use the p13 LED as debugging
}
void loop() {
// The LED will 'echo' the button
digitalWrite(13, mcp.digitalRead(0));
}
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