stm32_SPI基本函數(shù)
void SPI_RCC_config(void)
{
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1,ENABLE);
}
void SPI_GPIO_config(void)
{
GPIO_InitTypeDef GPIO_InitStructure;;
GPIO_InitStructure.GPIO_Pin=GPIO_Pin_5;//SCK
GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode=GPIO_Mode_AF_PP;
GPIO_Init(GPIOA,&GPIO_InitStructure);
GPIO_InitStructure.GPIO_Pin=GPIO_Pin_7;//MOSI
GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode=GPIO_Mode_AF_PP;
GPIO_Init(GPIOA,&GPIO_InitStructure);
GPIO_InitStructure.GPIO_Pin=GPIO_Pin_6;//MISO
GPIO_InitStructure.GPIO_Mode=GPIO_Mode_IN_FLOATING;
GPIO_Init(GPIOA,&GPIO_InitStructure);
GPIO_InitStructure.GPIO_Pin=GPIO_Pin_8;//cs
GPIO_InitStructure.GPIO_Mode=GPIO_Mode_Out_PP;
GPIO_Init(GPIOA,&GPIO_InitStructure);
}
void SPI_configuration(void)
{
SPI_InitTypeDef SPI_InitStructure;
SPI_InitStructure.SPI_Direction=SPI_Direction_2Lines_FullDuplex;//設(shè)置SPI單向或者雙向的數(shù)據(jù)模式:SPI設(shè)置為雙線雙向全雙工
SPI_InitStructure.SPI_Mode=SPI_Mode_Master;//設(shè)置SPI工作模式:設(shè)置為主SPI
SPI_InitStructure.SPI_DataSize=SPI_DataSize_8b;//設(shè)置SPI的數(shù)據(jù)大小:SPI發(fā)送接收8位幀結(jié)構(gòu)
SPI_InitStructure.SPI_CPOL=SPI_CPOL_High;//選擇了串行時(shí)鐘的穩(wěn)態(tài):時(shí)鐘懸空高
SPI_InitStructure.SPI_CPHA=SPI_CPHA_2Edge;//數(shù)據(jù)捕獲于第二個(gè)時(shí)鐘沿
SPI_InitStructure.SPI_NSS=SPI_NSS_Soft;//NSS信號(hào)由硬件（NSS管腳）還是軟件（使用SSI位）管理:內(nèi)部NSS信號(hào)有SSI位控制
SPI_InitStructure.SPI_BaudRatePrescaler=SPI_BaudRatePrescaler_256;//定義波特率預(yù)分頻的值:波特率預(yù)分頻值為256
SPI_InitStructure.SPI_FirstBit=SPI_FirstBit_MSB;//指定數(shù)據(jù)傳輸從MSB位還是LSB位開始:數(shù)據(jù)傳輸從MSB位開始
SPI_InitStructure.SPI_CRCPolynomial=7;//CRC值計(jì)算的多項(xiàng)式
SPI_Init(SPI1,&SPI_InitStructure);
SPI_Cmd(SPI1, ENABLE);//使能SPI外設(shè)
}
//SPIx 讀寫一個(gè)字節(jié)
//TxData:要寫入的字節(jié)
//返回值:讀取到的字節(jié)
u8 SPI_SendByte(u8 byte)
{
while(SPI_I2S_GetFlagStatus(SPI1,SPI_I2S_FLAG_TXE)==RESET);
SPI_I2S_SendData( SPI1,byte);
while(SPI_I2S_GetFlagStatus(SPI1,SPI_I2S_FLAG_RXNE)==RESET);
return SPI_I2S_ReceiveData(SPI1);
}
//SPI 速度設(shè)置函數(shù)
//SpeedSet:
//SPI_BaudRatePrescaler_2 2分頻 (SPI 36M@sys 72M)
//SPI_BaudRatePrescaler_8 8分頻 (SPI 9M@sys 72M)
//SPI_BaudRatePrescaler_16 16分頻 (SPI 4.5M@sys 72M)
//SPI_BaudRatePrescaler_256 256分頻 (SPI 281.25K@sys 72M)
void SPIx_Speedhigh(void)
{
SPI_InitTypeDef SPI_InitStructure;
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_2;
SPI_InitStructure.SPI_FirstBit=SPI_FirstBit_MSB;
SPI_InitStructure.SPI_CRCPolynomial=7;
SPI_Init(SPI1,&SPI_InitStructure);
SPI_Cmd(SPI1, ENABLE);
}
void SPIx_Speedlow(void)
{
SPI_InitTypeDef SPI_InitStructure;
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_256;
SPI_InitStructure.SPI_FirstBit=SPI_FirstBit_MSB;
SPI_InitStructure.SPI_CRCPolynomial=7;
SPI_Init(SPI1,&SPI_InitStructure);
SPI_Cmd(SPI1, ENABLE);
}
重難點(diǎn)：關(guān)于SPI_NSS可以選用三中配置
1：硬件主、從模式：浮空輸入或帶上拉輸入或帶下拉輸入
2：硬件主模式/NSS輸出管理
3：軟件模式 可作普通IO口
我們一般選用軟件模式，用一個(gè)IO做CS端
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