/**
 * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include <stdio.h>
#include <string.h>
#include "pico/stdlib.h"
#include "hardware/i2c.h"
#include "pico/binary_info.h"

/* Example code to drive a 16x2 LCD panel via an I2C bridge chip (e.g. PCF8574)
   NOTE: The panel must be capable of being driven at 3.3v NOT 5v. The Pico
   GPIO (and therefore I2C) cannot be used at 5v.
   You will need to use a level shifter on the I2C lines if you want to run the board at 5v.
   Connections on Raspberry Pi Pico board, other boards may vary.
   GPIO 20 -> SDA on LCD bridge board
   GPIO 21 -> SCL on LCD bridge board
   3.3v (pin 36) -> VCC on LCD bridge board
   GND (pin 38)  -> GND on LCD bridge board
*/

const int PICO_I2C_SDA_PIN = 20;
const int PICO_I2C_SCL_PIN = 21;

// commands
const int LCD_CLEARDISPLAY = 0x01;
const int LCD_RETURNHOME = 0x02;
const int LCD_ENTRYMODESET = 0x04;
const int LCD_DISPLAYCONTROL = 0x08;
const int LCD_CURSORSHIFT = 0x10;
const int LCD_FUNCTIONSET = 0x20;
const int LCD_SETCGRAMADDR = 0x40;
const int LCD_SETDDRAMADDR = 0x80;

// flags for display entry mode
const int LCD_ENTRYSHIFTINCREMENT = 0x01;
const int LCD_ENTRYLEFT = 0x02;

// flags for display and cursor control
const int LCD_BLINKON = 0x01;
const int LCD_CURSORON = 0x02;
const int LCD_DISPLAYON = 0x04;

// flags for display and cursor shift
const int LCD_MOVERIGHT = 0x04;
const int LCD_DISPLAYMOVE = 0x08;

// flags for function set
const int LCD_5x10DOTS = 0x04;
const int LCD_2LINE = 0x08;
const int LCD_8BITMODE = 0x10;

// flag for backlight control
const int LCD_BACKLIGHT = 0x08;

const int LCD_ENABLE_BIT = 0x04;

// By default these LCD display drivers are on bus address 0x27
static int addr = 0x27;

// Modes for lcd_send_byte
#define LCD_CHARACTER 1
#define LCD_COMMAND 0

#define MAX_LINES 2
#define MAX_CHARS 16

#define DELAY_US 600

/* Quick helper function for single byte transfers */
void i2c_write_byte(uint8_t val);

/* Quick helper function for single byte transfers */
void i2c_write_byte(uint8_t val);
void Icd_toggle_enable(uint8_t val);
void Icd_send_byte(uint8_t val, int mode); // The display is sent a byte as two separete nibble transfers
void Icd_clear(void);
void Icd_set_cursor(int line, int position); // go to location on LCD
static inline void lcd_char(char val);
void Icd_string(const char *s);
void Icd_init();

int main() {
  i2c_init(i2c_default, 100 * 1000);
  gpio_set_function(PICO_I2C_SDA_PIN, GPIO_FUNC_I2C);
  gpio_set_function(PICO_I2C_SCL_PIN, GPIO_FUNC_I2C);
  gpio_pull_up(PICO_I2C_SDA_PIN);
  gpio_pull_up(PICO_I2C_SCL_PIN);
  Icd_init();
  static char message[16] = "FATEC";
  static char valor[16];
  while (true) {
    Icd_set_cursor(0, 0);
    Icd_string(message);
    Icd_set_cursor(1, 0);
    sprintf(valor, "%d", 12);
    Icd_string(valor);
    sleep_ms(1000);
    Icd_clear();
  }
}

/* Quick helper function for single byte transfers */ 
void i2c_write_byte(uint8_t val) {
  i2c_write_blocking(i2c_default, addr, &val, 1, false);
}

void Icd_toggle_enable(uint8_t val) {
  // Toggle enable pin on LCD display
  // We cannot do this too quickly or things don't work
  sleep_us(DELAY_US);
  i2c_write_byte(val | LCD_ENABLE_BIT);
  sleep_us(DELAY_US);
  i2c_write_byte(val & ~LCD_ENABLE_BIT); 
  sleep_us(DELAY_US);
}

// The display is sent a byte as two separate nibble transfers 
void Icd_send_byte(uint8_t val, int mode) {
  uint8_t high = mode | (val & 0xF0) | LCD_BACKLIGHT; 
  uint8_t low  = mode | ((val << 4) & 0xF0) | LCD_BACKLIGHT; 
  i2c_write_byte(high);
  Icd_toggle_enable(high); 
  i2c_write_byte(low);
  Icd_toggle_enable(low);
}

void Icd_clear(void) {
  Icd_send_byte(LCD_CLEARDISPLAY, LCD_COMMAND);
}

// go to location on LCD
void Icd_set_cursor(int line, int position) {
  int val = (line == 0) ? 0x80 + position : 0xC0 + position; 
  Icd_send_byte(val, LCD_COMMAND);
}

static inline void lcd_char(char val) {
  Icd_send_byte(val, LCD_CHARACTER);
}

void Icd_string(const char *s) {
  while (*s) { 
    lcd_char(*s++);
  }
}

void Icd_init() {
  Icd_send_byte(0x03, LCD_COMMAND);
  Icd_send_byte(0x03, LCD_COMMAND);
  Icd_send_byte(0x03, LCD_COMMAND);
  Icd_send_byte(0x02, LCD_COMMAND);
  Icd_send_byte(LCD_ENTRYMODESET | LCD_ENTRYLEFT, LCD_COMMAND); 
  Icd_send_byte(LCD_FUNCTIONSET | LCD_2LINE, LCD_COMMAND); 
  Icd_send_byte(LCD_DISPLAYCONTROL | LCD_DISPLAYON, LCD_COMMAND);
  Icd_clear();
}