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