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STM32F103 series MCU의 hardware SPI interface를 사용하기 위해서 아래와 같이 GPIO 설정이 필요로 한다.
#define GPIO_HW_SPI GPIOA
#define GPIO_HW_SPI_CS GPIO_Pin_4 // NSS PIN
#define GPIO_HW_SPI_SCLK GPIO_Pin_5 // Clock
#define GPIO_HW_SPI_MISO GPIO_Pin_6 // Master Input to Slave Output
#define GPIO_HW_SPI_MOSI GPIO_Pin_7 // Master Output to Slave Input
#define HW_SPI_READ_BIT 0x80
#define HW_SPI_WRITE_BIT 0x00
/* Select hardware SPI: Chip Select pin low */
#define HW_SPI_CS_LOW() GPIO_ResetBits(GPIO_HW_SPI, GPIO_HW_SPI_CS)
/* Deselect hardware SPI: Chip Select pin high */
#define HW_SPI_CS_HIGH() GPIO_SetBits(GPIO_HW_SPI, GPIO_HW_SPI_CS)
void MXM1160_HW_SPI_GPIO_Init(void){
SPI_InitTypeDef SPI_InitStructure;
GPIO_InitTypeDef GPIO_InitStructure;
/* Enable SPI1 and GPIO clocks */
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_SPI1, ENABLE);
/* Configure SPI1 pins: SCK, MISO and MOSI */
GPIO_InitStructure.GPIO_Pin = GPIO_HW_SPI_SCLK | GPIO_HW_SPI_MOSI | GPIO_HW_SPI_MISO;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_Init(GPIO_HW_SPI, &GPIO_InitStructure);
/* Configure I/O for the sensor select */
GPIO_InitStructure.GPIO_Pin = GPIO_HW_SPI_CS;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_Init(GPIO_HW_SPI, &GPIO_InitStructure);
/* Deselect the hardware SPI : Sensor Select high */
HW_SPI_CS_HIGH();
/* SPI1 configuration */
SPI_InitStructure.SPI_Direction = SPI_Direction_2Lines_FullDuplex;
SPI_InitStructure.SPI_Mode = SPI_Mode_Master;
SPI_InitStructure.SPI_DataSize = SPI_DataSize_8b;
SPI_InitStructure.SPI_CPOL = SPI_CPOL_High;
SPI_InitStructure.SPI_CPHA = SPI_CPHA_2Edge;
SPI_InitStructure.SPI_NSS = SPI_NSS_Soft;
SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_16;
SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;
SPI_InitStructure.SPI_CRCPolynomial = 1;
SPI_Init(SPI1, &SPI_InitStructure);
/* Enable SPI1 */
SPI_Cmd(SPI1, ENABLE);
}
위의 'SPI_InitStructure.SPI_CPOL"와 'SPI_InitStructure.SPI_CPHA'는 사용자 개발 환경과 SPI 통신을 사용하는 slave chip의 통신 모드의 Clock Plarity (CPOL), Clock Phase (CPHA)의 의해 결정되므로 개별적으로 확인하길 바란다.
그 다음에 SPI 통신은 양방향 통신이기 때문에 Read / Write command에 따라 dummy byte 등 적절한 array index 관리를 해주면 된다.
void HW_SPI_Multi_TXRX(uint8_t Cmd, uint8_t addr, uint8_t count, uint8_t *pData)
{
uint8_t BufferSize = count;
uint8_t SPI_Dummy_Tx = 0x00;
uint8_t SPI_Dummy_Rx = 0x00;
// Check the Command mode and Address
SPI_Dummy_Tx = Cmd | addr;
HW_SPI_CS_LOW();
/* Wait for SPIy Tx buffer empty */
while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_TXE) == RESET);
/* Send SPIy data */
SPI_I2S_SendData(SPI1, SPI_Dummy_Tx);
/* Wait for SPIy data reception */
while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE) == RESET);
/* Read SPIy received data */
SPI_Dummy_Rx = SPI_I2S_ReceiveData(SPI1);
while(count>1){
/* Wait for SPIy Tx buffer empty */
while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_TXE) == RESET);
/* Send SPIy data */
SPI_I2S_SendData(SPI1, pData[BufferSize-count]);
/* Wait for SPIy data reception */
while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE) == RESET);
/* Read SPIy received data */
if ( Cmd == HW_SPI_READ_BIT ){
pData[BufferSize-count] = SPI_I2S_ReceiveData(SPI1);
}
else{
SPI_Dummy_Rx = SPI_I2S_ReceiveData(SPI1);
}
count--;
}
/* Wait for SPIy Tx buffer empty */
while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_TXE) == RESET);
/* Send SPIy data */
SPI_I2S_SendData(SPI1, pData[BufferSize-count]);
/* Wait for SPIy data reception */
while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE) == RESET);
/* Read SPIy received data */
if ( Cmd == HW_SPI_READ_BIT ){
pData[BufferSize-count] = SPI_I2S_ReceiveData(SPI1);
}
else{
SPI_Dummy_Rx = SPI_I2S_ReceiveData(SPI1);
}
HW_SPI_CS_HIGH();
}
마지막으로 SPI 통신의 waveform grpah 관련 자료는 구글링을 하면 되므로, 검색 스킬을 발휘하길 바란다.
끝.
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