/*
 * STM32 - ćwiczenie 5, I2C
 * projekt ,,Python w Elektronicznej Sieci''
 * Krzysztof Lasocki <krz.lasocki@gmail.com>
 *
 * opis działania I2C (znaczenie ACK, NACK, START, STOP, ...)
 * dla dociekliwych: https://www.ti.com/lit/an/slva704/slva704.pdf
 */
#include <libopencm3/cm3/common.h>
#include <libopencm3/stm32/rcc.h>
#include <libopencm3/stm32/gpio.h>
#include <libopencm3/cm3/scb.h>

#include <libopencm3/stm32/i2c.h>
#include <libopencm3/stm32/usart.h>

#include <libopencm3/cm3/nvic.h>

#include <stdio.h>
#include "uart.h"


/* logika działania jako układ slave I2C */

#define SLAVE_ADDR 0x0F

uint8_t slavebyte;

void i2c2_ev_isr(void){
  uint16_t sr1, sr2;

  sr1 = I2C_SR1(I2C2);
  printf("I2C ISR: sr1=0x%04x slavebyte=%d\n", sr1, slavebyte); // for demonstration / debug only

  // Address matched (Slave)
  if (sr1 & I2C_SR1_ADDR){
    // Clear the ADDR sequence by reading SR2.
    sr2 = I2C_SR2(I2C2);
    (void) sr2;
  }

  // Write request from master
  if (sr1 & I2C_SR1_RxNE){
    slavebyte = I2C_DR(I2C2);
    printf("I2C ISR: received %d\n", slavebyte); // for demonstration / debug only
    slavebyte *= 2; // slave logic is multiply by 2 ;)
  }

  // Read request from master
  if ((sr1 & I2C_SR1_TxE)){
    I2C_DR(I2C2) = slavebyte;
  }

  // Stop sequence detected (Slave)
  if (sr1 & I2C_SR1_STOPF){
    // Clear by write I2C_CR1
    I2C_CR1(I2C2) = I2C_CR1(I2C2);
  }
}


/* konfiguracja I2C - master i slave */

void i2c_setup(){
  rcc_periph_clock_enable(RCC_GPIOB);


  /* I2C1 - master; SDA=B7, SCL=B6 */
  rcc_periph_clock_enable(RCC_I2C1);

  i2c_reset(I2C1);
  i2c_peripheral_disable(I2C1);
  i2c_set_speed(I2C1, i2c_speed_sm_100k, 8);

  gpio_set_mode(GPIOB, GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_ALTFN_OPENDRAIN, GPIO6 | GPIO7);

  i2c_peripheral_enable(I2C1);


  /* I2C2 - slave; SDA=B11, SCL=B10 */
  rcc_periph_clock_enable(RCC_I2C2);

  i2c_reset(I2C2);
  i2c_peripheral_disable(I2C2);
  i2c_set_speed(I2C2, i2c_speed_sm_100k, 8);

  i2c_set_own_7bit_slave_address(I2C2, SLAVE_ADDR);

  nvic_enable_irq(NVIC_I2C2_EV_IRQ);

  gpio_set_mode(GPIOB, GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_ALTFN_OPENDRAIN, GPIO10 | GPIO11);

  i2c_enable_interrupt(I2C2, I2C_CR2_ITEVTEN );
  i2c_peripheral_enable(I2C2);

  i2c_enable_ack(I2C2);
}


/* funkcje zapisu i odczytu po I2C - wykorzystywane w trybie master */

void i2c_send_write(uint32_t peryf, uint8_t dane){
  i2c_send_start(peryf);
  // Czekaj na wysłanie startu
  while (!((I2C_SR1(peryf) & I2C_SR1_SB) & (I2C_SR2(peryf) & (I2C_SR2_MSL | I2C_SR2_BUSY))));

  i2c_send_7bit_address(peryf, SLAVE_ADDR, I2C_WRITE);
  // Czekaj na wysłanie adresu
  while (!(I2C_SR1(peryf) & I2C_SR1_ADDR));
  (void) I2C_SR2(peryf); // Wyczyść EV6

  i2c_send_data(peryf, dane);

  while (!(I2C_SR1(peryf) & (I2C_SR1_BTF))); // czekaj na wyslanie danych

  i2c_send_stop(peryf);
}


uint8_t i2c_send_read(uint32_t peryf){
  uint8_t dane;

  i2c_send_start(peryf);
  // Czekaj na wysłanie startu
  while (!((I2C_SR1(peryf) & I2C_SR1_SB) & (I2C_SR2(peryf) & (I2C_SR2_MSL | I2C_SR2_BUSY))));

  i2c_send_7bit_address(peryf, SLAVE_ADDR, I2C_READ);
  // Czekaj na wysłanie adresu
  while (!(I2C_SR1(peryf) & I2C_SR1_ADDR));
  (void) I2C_SR2(peryf); // Wyczyść EV6

  // Czekaj aż otrzymasz 1 bajt danych
  while (!(I2C_SR1(peryf) & I2C_SR1_RxNE));
  dane = i2c_get_data(peryf);

  i2c_send_stop(peryf);

  return dane;
}


/* pętla główna - konfiguracja oraz logika mastera i2c */

int main(){
  rcc_periph_clock_enable(RCC_GPIOC);
  gpio_set_mode(GPIOC, GPIO_MODE_OUTPUT_2_MHZ,
		GPIO_CNF_OUTPUT_PUSHPULL, GPIO13 | GPIO14);
  usart_setup();
  
  for(int j = 0; j < 10; j++) {
    printf("...%d\n", j);
    for (int i = 0; i < 150000; i++) __asm__("nop");
    gpio_toggle(GPIOC, GPIO13);
  }

  SCB_VTOR = FLASH_BASE;

  uint8_t k = 0;
  i2c_setup();

  while(1){
    for (int i = 0; i < 500000; i++) __asm__("nop");

    printf("Wysylam %d\n", k);
    i2c_send_write(I2C1, k);
    uint8_t wynik = i2c_send_read(I2C1);
    printf("Odebralem %d\n", wynik);
    k++;
  }
}