初次使用STM32有些不太明白,此次调试经验奉献出来与大家分享!
系统:STM32 + SD + FATFS
STM32与SD卡的连接如下定义,PB口
#define SD_SCK GPIO_Pin_3
#define SD_MISO GPIO_Pin_4
#define SD_MOSI GPIO_Pin_5
#define SD_CS GPIO_Pin_7
我想使用SPI1并重映射引脚使用时注意的事项如下:
1.使能PB0时钟 RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB,ENABLE);
2.使能AFIO时钟RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE);
3.使能SPI1时钟RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1 , ENABLE);
4.禁用JTAG时钟复用 GPIO_PinRemapConfig(GPIO_Remap_SWJ_JTAGDisable , ENABLE);
5.SPI1引脚重映射 GPIO_PinRemapConfig(GPIO_Remap_SPI1,ENABLE);
接着初始化GPIO和SPI1即可,如:
void SpiOpen(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
SPI_InitTypeDef SPI_InitStructure;
/* Configure SPI1 pins: SCKand MOSI */
GPIO_InitStructure.GPIO_Pin = SD_MOSI|SD_SCK|SD_MISO;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_Init(GPIOB, &GPIO_InitStructure);
/* Configure PB7 pin: CS pin */
GPIO_InitStructure.GPIO_Pin = SD_CS;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_Init(GPIOB, &GPIO_InitStructure);
GPIO_SetBits(GPIOB,SD_CS);
/* SPI1 Config */
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);
/* SPI1 enable */
SPI_Cmd(SPI1, ENABLE);
}
可是这一切完成的时候结果却与想象的不同,无法在SD卡内创建文件,找一个晚上没有结果
不得已采用另一种方法:软件模拟SPI测试了一下,
结果另人出呼意料,一次搞定,没有任何问题,但为了效率还是希望使用硬SPI口,于是从引脚重映射上寻找原因
又费了一晚上无果
第三个晚上:经过无数次的 改动 + 测试 终于OK了,问题出在哪里了呢?
原来SD卡的初始时钟不一定是<400KHz就行
ST标准库初始化系统时APB2时钟为72MHz,经过256分频波特率约等于 280KHz
(SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_256;)
对于我测试用的SD卡这个速度仍太快,于是降APB2时钟进行测试,OK!
RCC_PCLK2Config(RCC_HCLK_Div4); //72/4=18MHz
仅仅是一行代码,这就是初学代价!,哈哈.
另外要说明的是,在MISO引脚上加了一个22k上接电阻.
代码:
//#define USE_SOFT_SPI
#ifdef USE_SOFT_SPI
BYTE g_SPISpeedFlag=0;
static void delay_bus(void)
{
unsigned int i=100;
if(g_SPISpeedFlag) //高速模式 < 25MHz
i=10;
while(--i) //低速模式 < 400KHz
__nop();
}
void SpiOpen(void)
{
//IO初始化用结构体
GPIO_InitTypeDef GPIO_InitStructure;
//输出引脚初始化
GPIO_InitStructure.GPIO_Pin=SD_SCK|SD_CS|SD_MOSI;
GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_Init(GPIOB, &GPIO_InitStructure);
//输入引脚配置
GPIO_InitStructure.GPIO_Pin=SD_MISO;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;//GPIO_Mode_IN_FLOATING ;
GPIO_Init(GPIOB, &GPIO_InitStructure);
//设置端口初始电平
GPIO_SetBits(GPIOB,SD_CS);
GPIO_SetBits(GPIOB,SD_SCK);
g_SPISpeedFlag=0;
}
void SpiClose(void)
{
GPIO_SetBits(GPIOB,SD_CS);
GPIO_SetBits(GPIOB,SD_SCK);
Stat &= ~STA_NOINIT;
}
void SPI_SetHeighSpeed(void)
{
g_SPISpeedFlag=1;
}
BYTE SPI_ReadWriteByte(BYTE outgoing)
{
uint32_t i;
uint8_t ret=0;
delay_bus();
for(i=0;i<8;i++)
{
ret<<=1;
if(outgoing &0x80) //主设备锁存数据
GPIO_SetBits(GPIOB,SD_MOSI);
else
GPIO_ResetBits(GPIOB,SD_MOSI);
GPIO_ResetBits(GPIOB,SD_SCK); //产生第一个时钟沿,让从设备也在此时锁存数据
delay_bus();
if(GPIO_ReadInputDataBit(GPIOB,SD_MISO)) //主设备采样
ret|=1;
GPIO_SetBits(GPIOB,SD_SCK); //产生第二个时钟沿,让从设备也在此时采样
delay_bus();
outgoing<<=1;
}
return ret;
}
#else //硬件SPI 使用SPI1引脚重映射
void SpiOpen(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
SPI_InitTypeDef SPI_InitStructure;
GPIO_PinRemapConfig(GPIO_Remap_SPI1,ENABLE);
/* Configure SPI1 pins: SCKand MOSI */
GPIO_InitStructure.GPIO_Pin = SD_MOSI|SD_SCK|SD_MISO;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_Init(GPIOB, &GPIO_InitStructure);
/* Configure PB7 pin: CS pin */
GPIO_InitStructure.GPIO_Pin = SD_CS;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_Init(GPIOB, &GPIO_InitStructure);
GPIO_SetBits(GPIOB,SD_CS);
/* SPI1 Config */
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);
/* SPI1 enable */
SPI_Cmd(SPI1, ENABLE);
}
void SpiClose(void)
{
SPI_Cmd(SPI1, DISABLE);
Stat &= ~STA_NOINIT;
}
void SPI_SetHeighSpeed(void)
{
SPI_InitTypeDef SPI_InitStructure;
/* SPI1 Config */
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_4;
SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;
SPI_InitStructure.SPI_CRCPolynomial = 7;
SPI_Init(SPI1, &SPI_InitStructure);
SPI_Cmd(SPI1, ENABLE);
}
BYTE SPI_ReadWriteByte(BYTE outgoing)
{
/* Loop while DR register in not emplty */
while(SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_TXE) == RESET);
/* Send byte through the SPI1 peripheral */
SPI_I2S_SendData(SPI1, outgoing);
/* Wait to receive a byte */
while(SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE) == RESET);
/* Return the byte read from the SPI bus */
return SPI_I2S_ReceiveData(SPI1);
}
#endif
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