#include <stdio.h>          //provides printf function
#include <string.h>         //provides memset etc

#include "pico/stdlib.h"    //provides standard library for the pico
#include "hardware/gpio.h"  //configure gpio
#include "hardware/i2c.h"   //configure i2c

#define I2C_INSTANCE i2c0
#define PICO_I2C_SDA_PIN 16
#define PICO_I2C_SCL_PIN 17

// I2C peripheral adapted from https://github.com/GoodAlex223/rule_indicators

#define EEPROM_ADDRESS 0x50
#define EEPROM_REG 0x0000

//avoid dumping all 32k
#define EEPROM_DUMP_LIMIT 0x40
//#define EEPROM_DUMP_LIMIT 0x8000 

int main()
{
  stdio_init_all();

  // This example will use I2C0 on the selected SDA and SCL pins
  i2c_init(I2C_INSTANCE, 100 * 1000);
  gpio_set_function(PICO_I2C_SDA_PIN, GPIO_FUNC_I2C);
  gpio_set_function(PICO_I2C_SCL_PIN, GPIO_FUNC_I2C);

  //the pico has a board with hardware pullups attached
  gpio_pull_up(PICO_I2C_SDA_PIN);
  gpio_pull_up(PICO_I2C_SCL_PIN);

  printf("I2C EEPROM Example\n");
  const char msg[]="Hello World!";
  char write_command[sizeof(msg)+2]={0};
  memcpy(write_command+2,msg,sizeof(msg));
  write_command[0]=(EEPROM_REG>>8)&0xFF;
  write_command[1]=EEPROM_REG&0xFF;

  printf("Writing: %s\n",msg);
  i2c_write_blocking(i2c0, EEPROM_ADDRESS, (uint8_t *)write_command, sizeof(write_command), false);
  sleep_ms(100);

  char read_command[2]={0};
  char read_buffer[sizeof(msg)+1]={0};
  read_command[0]=EEPROM_REG&0xFF;
  read_command[1]=(EEPROM_REG>>8)&0xFF;

  i2c_write_blocking(i2c0, EEPROM_ADDRESS, (uint8_t *)read_command, sizeof(read_command), true);
  i2c_read_blocking(i2c0, EEPROM_ADDRESS, (uint8_t *)read_buffer, sizeof(read_buffer)-1, false);
  printf("Read %s\n",read_buffer);

  // use converter to check online https://www.rapidtables.com/convert/number/hex-to-ascii.html
  printf("          0   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F\n");
  for (int addr = 0; addr<EEPROM_DUMP_LIMIT; ++addr) {
    if (addr % 16 == 0) {
      printf("%08x ", addr);
    }
    char dump_command[2]={0};
    char dump_buffer[1]={0};
    dump_command[0]=(addr>>8)&0xFF;
    dump_command[1]=addr&0xFF;
    
    i2c_write_blocking(i2c0, EEPROM_ADDRESS, (uint8_t *)&dump_command, sizeof(dump_command), true);
    i2c_read_blocking(i2c0, EEPROM_ADDRESS, (uint8_t *)dump_buffer, sizeof(dump_buffer), false);
    printf("%2X",dump_buffer[0]);
    printf(addr % 16 == 15 ? "\n" : "  ");
    
  }
  printf("\n");

  while (true) {
    sleep_ms(1000);
  }
}