// PIC18 in C - Versione 0.1a - Settembre 2014
// Copyright (c) 2014 VincenzoV.net
// Creative Commons | Attribuzione-Condividi allo stesso modo 3.0 Unported.
// Creative Commons | Attribution-Share Alike 3.0 Unported
// https://www.vincenzov.net/tutorial/PIC18/i2c-PLIB.htm

// I2C master - MCP23017

#define MCP23017_ADDR 0x20   // I2C device adress
#define LEDS 0xA1            // 10100001 - Some LED is ON, others is OFF

// TABLE 1-2: REGISTER ADDRESSES - Default bank 0
#define MCP23017_IODIRB 1	   // IODIRB register address
#define MCP23017_GPIOB 0x013   // GPIOB register address

#include "configurationbits.h"

#include <i2c.h>

void I2C_error_handler(int error_code); //

void main(void) // Program start here
{
    unsigned char addrRW;

    OSCCON = 0x70; // Set internal clock to 16 MHz
    SSPADD = 0x27; // Set 100 kHz clock ( @ 16 MHz ) 

    OpenI2C(MASTER, SLEW_ON); // I2C Master mode, Slew Rate enabled

    IdleI2C();  // Wait until the bus is idle
    StartI2C(); // Send START condition

    addrRW = MCP23017_ADDR << 1; // 7 bit address + Write bit

    IdleI2C();                 // Wait until the bus is idle
    if (WriteI2C(addrRW) < 0)  // Send address with R/W set for write - Error in WriteI2C() documentation!
        I2C_error_handler(-1); 

    // Configure port B as output - see MCP23017 data sheet
    IdleI2C(); // Wait until the bus is idle
    if (WriteI2C(MCP23017_IODIRB) < 0) // Send register address
        I2C_error_handler(-1); 
    
    IdleI2C(); // Wait until the bus is idle
    if (WriteI2C(0x00) < 0) // Send Output
        I2C_error_handler(-1); 

    IdleI2C(); // Wait until the bus is idle
    StopI2C(); // Send STOP condition

    // On/Off some LEDs
    IdleI2C(); // Wait until the bus is idle
    StartI2C(); // Send START condition

    addrRW = MCP23017_ADDR << 1; // 7 bit address + Write bit

    IdleI2C(); // Wait until the bus is idle
    if (WriteI2C(addrRW) < 0) // Send address with R/W set for write
        I2C_error_handler(-1); 

    // Put data to PortB
    IdleI2C(); // Wait until the bus is idle
    if (WriteI2C(MCP23017_GPIOB) < 0) // Send register address
        I2C_error_handler(-1);

    IdleI2C(); // Wait until the bus is idle
    if (WriteI2C(LEDS) < 0) // Send led ON/OFF
        I2C_error_handler(-1);

    IdleI2C(); // Wait until the bus is idle
    StopI2C(); // Send STOP condition

    CloseI2C();

    while (1);
}

void I2C_error_handler(int error_code) { // Error handler... emty
}