#include "stm32f10x.h"
#include "I2C.h"
#include <armv30_std.h>
#include <stm32f10x.h>

#define I2C_TIMEOUT 100000

static uint8_t I2C_WaitFlag(volatile uint16_t *reg, uint16_t flag)
{
    uint32_t timeout = I2C_TIMEOUT;

    while(!(*reg & flag))
    {
        if(--timeout == 0)
            return 0;
    }
    return 1;
}

void I2C1_Init(void)
{
    /* 1. Clock aktivieren */
    RCC->APB2ENR |= RCC_APB2ENR_IOPBEN;   // GPIOB
    RCC->APB1ENR |= RCC_APB1ENR_I2C1EN;   // I2C1

    /* 2. GPIO konfigurieren: PB6=SCL, PB7=SDA */
    GPIOB->CRL &= ~((0xF << 24) | (0xF << 28));
    GPIOB->CRL |=  ((0xB << 24) | (0xB << 28));  
    // 0xB = Alternate Open Drain, 50MHz

    /* 3. I2C Reset */
    I2C1->CR1 |= I2C_CR1_SWRST;
    I2C1->CR1 &= ~I2C_CR1_SWRST;

    /* 4. Peripherietakt einstellen */
    I2C1->CR2 = 36;          // APB1 = 36 MHz
    I2C1->CCR = 180;         // 100kHz
    I2C1->TRISE = 37;        // laut Datenblatt

    /* 5. Enable */
    I2C1->CR1 |= I2C_CR1_PE;
}

void startSeq(void)
{
	I2C1->CR1 |= I2C_CR1_START;            // START setzen
	while(!(I2C1->SR1 & I2C_SR1_SB));      // Warten bis START gesendet
}

void stopSeq(void)
{
    I2C1->CR1 |= I2C_CR1_STOP;
}

uint8_t I2C_SendAddress_Write(uint8_t addr)
{
    I2C1->DR = addr << 1;     // R/W = 0

    if(!I2C_WaitFlag(&I2C1->SR1, I2C_SR1_ADDR))
        return 0;

    (void)I2C1->SR1;          // ADDR löschen
    (void)I2C1->SR2;

    return 1;
}