void SPI1_IRQHandler(void)
{
	uint32_t					uiSpRegisterValue;
	uint16_t					uiBuffer;
	uint8_t						uiTemp;

	// ON
	// GPIOD->BSRRL = LED3_PIN;

	uiSpRegisterValue = SPI1->SR;

	// receive data
	if((uiSpRegisterValue & SPI_SR_RXNE) != 0)
	{
		// byte received
		uiBuffer = SPI1->DR;

		if(bRecCount_g == 0)
		{
			// shift data because MSB first
			uiRecData_g |= ((uiBuffer & 0x00FF) << 8);
		}
		else
		{
			uiRecData_g |= (uiBuffer & 0x00FF);

			// set CS signal to 1
			GPIO_SetBits(GPIOA, GPIO_Pin_15);

			SPI_Cmd(SPI1, DISABLE);

		}

		bRecCount_g++;

	}

	// send data
	if((uiSpRegisterValue & SPI_SR_TXE) != 0)
	{
		if(bRecCount_g == 0)
		{
			SPI1->DR =  bSendData_g;
		}

	}

	// check Errorinterrupt
	if((uiSpRegisterValue & 0x78) != 0)
	{
		// byte data
		uiBuffer = SPI1->DR;
		// read status register to clear interrupt
		uiSpRegisterValue = (uint8_t)SPI1->SR;

		// TODO: handle error????

	}

	SPI_I2S_ClearITPendingBit(SPI1, 0xFF);
	// OFF
	// GPIOD->BSRRH = LED3_PIN;

}