SPI是Serial Peripheral Interface的缩写,直接翻译为串行外设接口。它是一种短距离、高速、全双工、同步的串口通信总线,用于在嵌入式系统中连接微控制器与多种外设。
SPI总线具有以下特点:
目前市场上许多单片机都带有SPI接口,常见的有:
这些单片机都具有不同的处理能力、存储容量和外设支持能力,可以根据具体的应用需求进行选择。
SPI接口广泛应用于各种外设的控制和数据传输,如:
在使用SPI接口进行通信时,需要确认以下参数:
下面是使用STM32F103单片机通过SPI控制OLED显示屏的示例代码:
```c
/* 根据实际情况修改以下宏定义 */
#define OLED_CS_Pin GPIO_Pin_4
#define OLED_DC_Pin GPIO_Pin_5
#define OLED_RST_Pin GPIO_Pin_6
#define OLED_Port GPIOA
#define OLED_SPI SPI1
/* OLED初始化 */
void OLED_Init(void) {
GPIO_InitTypeDef GPIO_InitStructure;
SPI_InitTypeDef SPI_InitStructure;
/* GPIO时钟使能 */
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
/* OLED引脚设置 */
GPIO_InitStructure.GPIO_Pin = OLED_CS_Pin | OLED_DC_Pin | OLED_RST_Pin;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_Init(OLED_Port, &GPIO_InitStructure);
/* SPI时钟使能 */
RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1, ENABLE);
/* SPI设置 */
SPI_InitStructure.SPI_Direction = SPI_Direction_1Line_Tx;
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; // 72M/4=18MHz
SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;
SPI_Init(OLED_SPI, &SPI_InitStructure);
/* SPI使能 */
SPI_Cmd(OLED_SPI, ENABLE);
/* OLED硬件复位 */
OLED_RST = 0;
delay_us(1000);
OLED_RST = 1;
/* OLED初始化 */
OLED_Write_Command(0xAE);
OLED_Write_Command(0xD5);
OLED_Write_Command(0x80);
OLED_Write_Command(0xA8);
OLED_Write_Command(0x3F);
OLED_Write_Command(0xD3);
OLED_Write_Command(0x00);
OLED_Write_Command(0x40);
OLED_Write_Command(0x8D);
OLED_Write_Command(0x14);
OLED_Write_Command(0x20);
OLED_Write_Command(0x00);
OLED_Write_Command(0xA1);
OLED_Write_Command(0xC8);
OLED_Write_Command(0xDA);
OLED_Write_Command(0x12);
OLED_Write_Command(0x81);
OLED_Write_Command(0xCF);
OLED_Write_Command(0xD9);
OLED_Write_Command(0xF1);
OLED_Write_Command(0xDB);
OLED_Write_Command(0x40);
OLED_Write_Command(0xA4);
OLED_Write_Command(0xA6);
OLED_Write_Command(0xAF);
/* 清屏 */
OLED_Clear();
/* OLED写命令 */
void OLED_Write_Command(uint8_t command) {
OLED_DC = 0;
OLED_CS = 0;
SPI_I2S_SendData(OLED_SPI, command);
while (SPI_I2S_GetFlagStatus(OLED_SPI, SPI_I2S_FLAG_BSY) != RESET)
;
OLED_CS = 1;
/* OLED写数据 */
void OLED_Write_Data(uint8_t data) {
OLED_DC = 1;
OLED_CS = 0;
SPI_I2S_SendData(OLED_SPI, data);
while (SPI_I2S_GetFlagStatus(OLED_SPI, SPI_I2S_FLAG_BSY) != RESET)
;
OLED_CS = 1;
/* OLED清屏 */
void OLED_Clear(void) {
uint8_t i, n;
for (i = 0; i < 8; i++) {
OLED_Write_Command(0xb0 + i); //设置页地址
OLED_Write_Command(0x00); //设置显示位置—列低地址
OLED_Write_Command(0x10); //设置显示位置—列高地址
for (n = 0; n < 128; n++)
OLED_Write_Data(0x00);
}
```