i2csw.cpp

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//Ìîäóëü ïðîãðàììíîé ðåàëèçàöèè øèíû I2C

//----------------------- Èñïîëüçóåìûå ðåñóðñû: ------------------------------

//Èñïîëüçóþòñÿ ïèíû SCL (PB8) è SDA (PB9).
//Äëÿ ôîðìèðîâàíèÿ òàéìèíãîâ øèíû èñïîëüçóåòñÿ òàéìåð TIM16.

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#include "main.h"
#include "systimer.h"
#include "i2csw.h"

//----------------------------- Êîíñòàíòû: -----------------------------------

#define I2C_CLK    100 //÷àñòîòà øèíû I2C, êÃö

#define I2C_DELAY (APB2_CLOCK / 1000 / I2C_CLK / 2 - 18)

//----------------------------------------------------------------------------
//----------------------------- Êëàññ TI2Csw: --------------------------------
//----------------------------------------------------------------------------

//----------------------------- Èíèöèàëèçàöèÿ: -------------------------------

TGpio<PORTB, PIN8> TI2Csw::Pin_SCL; 
TGpio<PORTB, PIN9> TI2Csw::Pin_SDA;

void TI2Csw::Init(void)
{
  Pin_SCL.Init(OUT_OD_2M, OUT_HI);
  Pin_SDA.Init(OUT_OD_2M, OUT_HI);

  RCC->APB2ENR |= RCC_APB2ENR_TIM16EN; //âêëþ÷åíèå òàêòèðîâàíèÿ TIM16
  TIM16->PSC = 0;                      //çàãðóçêà ïðåñêàëåðà
  TIM16->ARR = 0xFFFF;                 //ïåðèîä
  TIM16->CR1 = TIM_CR1_CEN;            //ðàçðåøåíèå òàéìåðà
  
  Free(); //ñáðîñ I2C
  Stop();
}

//------------------------ Îñâîáîæäåíèå øèíû I2C: ----------------------------

void TI2Csw::Free(void)
{
  for(char i = 0; i < 9; i++)
  {
    if(Pin_SDA) break;
    Pin_SCL = 0;
    BitDelay();
    Pin_SCL = 1;
    BitDelay();
  }
}

//------------------- Ãåíåðàöèÿ óñëîâèÿ "ÑÒÀÐÒ" íà I2C: ----------------------

void TI2Csw::Start(void)
{
  Pin_SDA = 0;
  BitDelay();
}

//------------------------- Çàïèñü áàéòà ïî I2C: -----------------------------

bool TI2Csw::Write(char data)
{
  bool ack = 0;
  for(char i = 0; i < 8; i++)
  {
    Pin_SCL = 0;
    if(data & 0x80)
      Pin_SDA = 1;
        else Pin_SDA = 0;
    data <<= 1;    
    BitDelay();
    Pin_SCL = 1;
    BitDelay();
  }
  Pin_SCL = 0;
  Pin_SDA = 1;
  BitDelay();
  Pin_SCL = 1;
  BitDelay();
  ack = !Pin_SDA;
  BitDelay();
  return(ack);
}

//------------------------- ×òåíèå áàéòà ïî I2C: -----------------------------

char TI2Csw::Read(bool ack)
{
  char data;
  for(char i = 0; i < 8; i++)
  {
    Pin_SCL = 0;
    Pin_SDA = 1;
    BitDelay();
    Pin_SCL = 1;
    BitDelay();
    data = data << 1;
    if(Pin_SDA) data |= 0x01;
  }
  Pin_SCL = 0;
  Pin_SDA = !ack;
  BitDelay();
  Pin_SCL = 1;
  BitDelay();
  return(data);
}

//------------------- Ãåíåðàöèÿ óñëîâèÿ "ÑÒÎÏ" íà I2C: -----------------------

void TI2Csw::Stop(void)
{
  Pin_SCL = 0;
  Pin_SDA = 0;
  BitDelay();
  Pin_SCL = 1;
  BitDelay();
  Pin_SDA = 1;
  BitDelay();
}

//---------------------- Çàäåðæêà 1/2 ïåðèîäà I2C: ---------------------------

void TI2Csw::BitDelay(void)
{
  TIM16->CNT = 0;
  while(TIM16->CNT < I2C_DELAY);
}

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