gistfile1.c

//
// This file is part of the GNU ARM Eclipse distribution.
// Copyright (c) 2014 Liviu Ionescu.
//

// ----------------------------------------------------------------------------

#include <stdio.h>
#include "diag/Trace.h"
#include <stm32f30x.h>
#include <stm32f30x_i2c.h>
#include <stm32f30x_rcc.h>
#include <stm32f30x_gpio.h>

// ----------------------------------------------------------------------------
//
// Standalone STM32F3 empty sample (trace via ITM).
//
// Trace support is enabled by adding the TRACE macro definition.
// By default the trace messages are forwarded to the ITM output,
// but can be rerouted to any device or completely suppressed, by
// changing the definitions required in system/src/diag/trace_impl.c
// (currently OS_USE_TRACE_ITM, OS_USE_TRACE_SEMIHOSTING_DEBUG/_STDOUT).
//

// ----- main() ---------------------------------------------------------------

// Sample pragmas to cope with warnings. Please note the related line at
// the end of this function, used to pop the compiler diagnostics status.
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-parameter"
#pragma GCC diagnostic ignored "-Wmissing-declarations"
#pragma GCC diagnostic ignored "-Wreturn-type"

static const int I2C_TIMEOUT = 65536;
unsigned char i2c_buffer[256];

uint8_t i2c_read(uint8_t DeviceAddr, uint8_t RegAddr, uint8_t* pBuffer, uint16_t len)
{
  uint32_t timeout = I2C_TIMEOUT;
  while(I2C_GetFlagStatus(I2C1, I2C_ISR_BUSY) != RESET)
  {
    if((timeout--) == 0) return -1;
  }
  I2C_TransferHandling(I2C1, DeviceAddr<<1, 1, I2C_SoftEnd_Mode, I2C_Generate_Start_Write);

  timeout = I2C_TIMEOUT;
  while(I2C_GetFlagStatus(I2C1, I2C_ISR_TXIS) == RESET)
  {
    if((timeout--) == 0) return -1;
  }

  I2C_SendData(I2C1, RegAddr);

  timeout = I2C_TIMEOUT;
  while(I2C_GetFlagStatus(I2C1, I2C_ISR_TC) == RESET)
  {
    if((timeout--) == 0) return -1;
  }

  I2C_TransferHandling(I2C1, DeviceAddr<<1, len, I2C_AutoEnd_Mode, I2C_Generate_Start_Read);

  for (int i = 0; i < len; ++i) {
	  while(I2C_GetFlagStatus(I2C1, I2C_ISR_RXNE) == RESET)
	  {
		  if((timeout--) == 0) return -1;
	  }

	  pBuffer[i] = I2C_ReceiveData(I2C1);
  }

  timeout = I2C_TIMEOUT;
  while(I2C_GetFlagStatus(I2C1, I2C_ISR_STOPF) == RESET)
  {
    if((timeout--) == 0) return -1;
  }
  I2C_ClearFlag(I2C1, I2C_ICR_STOPCF);

  return 0;
}

void init_i2c(void)
{
	GPIO_InitTypeDef GPIO_InitStructure;
	I2C_InitTypeDef  I2C_InitStructure;

	RCC_I2CCLKConfig(RCC_I2C1CLK_SYSCLK);


	RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2C1, ENABLE);
	RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOB, ENABLE);

	GPIO_PinAFConfig(GPIOB, GPIO_PinSource6, GPIO_AF_4);
	GPIO_PinAFConfig(GPIOB, GPIO_PinSource7, GPIO_AF_4);

	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
	GPIO_InitStructure.GPIO_OType = GPIO_OType_OD;
	GPIO_InitStructure.GPIO_PuPd  = GPIO_PuPd_NOPULL;
	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;
	GPIO_Init(GPIOB, &GPIO_InitStructure);

	GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_7;
	GPIO_Init(GPIOB, &GPIO_InitStructure);

	I2C_DeInit(I2C1);
	I2C_StructInit(&I2C_InitStructure);
	I2C_InitStructure.I2C_Mode = I2C_Mode_I2C;
	I2C_InitStructure.I2C_AnalogFilter = I2C_AnalogFilter_Enable;
	I2C_InitStructure.I2C_DigitalFilter = 0x00;
	I2C_InitStructure.I2C_Ack = I2C_Ack_Enable;
	I2C_InitStructure.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit;
	I2C_InitStructure.I2C_Timing = 0xC062121F;

	I2C_Init(I2C1, &I2C_InitStructure);
	I2C_Cmd(I2C1, ENABLE);
}

int
main(int argc, char* argv[])
{
	// At this stage the system clock should have already been configured
	// at high speed.

	init_i2c();

  // Infinite loop
  while (1)
    {
	  i2c_read(0x42, 0x00, i2c_buffer, 22);
    }
}

#pragma GCC diagnostic pop

// ----------------------------------------------------------------------------