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pfowler |
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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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// Output #0 is on pin 21 so connect an LED or whatever from that to ground
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Adafruit_MCP23017 mcp;
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uint8_t mcp_inthit = 0;
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uint8_t leda_time = 0;
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uint8_t ledon = 0;
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void setup() {
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Serial.begin(9600);
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mcp.begin(); // use default address 0
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// Setup configuration
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mcp.writeReg(MCP23017_IOCONA, B01100000); // Dont mirror, disable sequential access
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mcp.writeReg(MCP23017_IOCONB, B01100000); // Dont mirror, disable sequential access
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// 1------- // BANK: 1 = Reg in different bank, 0 - Registers in seq
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// -1------ // MIRROR: Mirror interrupts if true
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// --1----- // SEQOP: 1 = Sequential access (AddrPtr does not increment)
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// ---1---- // DISSLW: Slew rate control for SDA
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// ----1--- // HAEN: Not used in MCP23017
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// -----1-- // ODR: 1 = INT pin as open-drain, 0 = Active driver
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// ------1- // INTPOL: Set polarity of INT output 1 = HIGH, 0 = Low
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// -------1 //
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// Setup pin directions
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mcp.writeReg(MCP23017_IODIRA, B00000000);
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mcp.writeReg(MCP23017_IODIRB, B10000000);
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// Enable pull-ups on ports
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mcp.writeReg(MCP23017_GPPUA, B00000000);
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mcp.writeReg(MCP23017_GPPUB, B10000000);
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// Setup pin polarity on ports
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mcp.writeReg(MCP23017_IPOLA, B00000000);
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mcp.writeReg(MCP23017_IPOLA, B10000000);
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// Set default values for pin on change
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mcp.writeReg(MCP23017_DEFVALA, B00000000);
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mcp.writeReg(MCP23017_DEFVALB, B00000000);
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// Enable 'default value detection' on ports
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mcp.writeReg(MCP23017_INTCONA, B00000000);
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mcp.writeReg(MCP23017_INTCONB, B00000000);
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// Enable interrupts on ports
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mcp.writeReg(MCP23017_GPINTENA, B00000000); //Enable interrupts on PORTA,0
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mcp.writeReg(MCP23017_GPINTENB, B10000000); // Enable interrupts on PORTB,7
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mcp.pinMode(7, OUTPUT);
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mcp.digitalWrite(7, LOW);
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mcp.pinMode(8, OUTPUT);
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mcp.digitalWrite(8, LOW);
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pinMode(13, OUTPUT);
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mcp.readReg(MCP23017_INTCAPA);
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mcp.readReg(MCP23017_INTCAPB);
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attachInterrupt(0, mcp_int, FALLING);
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}
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void loop() {
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if (mcp_inthit) {
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mcp_inthit = 0;
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handleMCP_int();
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}
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if (leda_time>0)
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leda_time--;
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if (leda_time==0 && ledon) {
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mcp.digitalWrite(8, 0);
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ledon = 0;
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}
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delay(1);
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}
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void handleMCP_int() {
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uint8_t srca = mcp.readReg(MCP23017_INTFA);
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uint8_t srcb = mcp.readReg(MCP23017_INTFB);
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uint8_t a = mcp.readReg(MCP23017_INTCAPA);
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uint8_t b = mcp.readReg(MCP23017_INTCAPB);
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if (bitRead(srcb, 7) && bitRead(b, 7)) {
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mcp.digitalWrite(8, 1);
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leda_time = 1000;
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ledon = 1;
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}
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}
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void mcp_int(void) {
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mcp_inthit = 1;
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}
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