如何通过 MISO 引脚使用 stm32f103（主）获取 nRF24l01（从）寄存器数据

Question

我正在尝试为 stm32f103 目标设备为 nRF24l01 制作自定义库，并且正在为主要 TX 设备编写代码。 在这里，我试图通过发送 R_REGISTER 命令以及我正在寻找的地址来读取 nRF 的寄存器内容，但我无法弄清楚在 R_REGISTER 命令发送后如何读取数据。

我正在使用标准 stm32f10x.h header 文件，该文件与 Kiel uVision5 上的启动文件一起提供。

以下是配置，

时钟设置

RCC->CR |= RCC_CR_HSION;    //HSI on
while( !(RCC_CR_HSIRDY & (RCC->CR)) );  //wait till its ready
//clocks for peripherals 
RCC->APB2ENR |= RCC_APB2ENR_IOPAEN; //enable clock forport A
RCC->APB2ENR |= RCC_APB2ENR_AFIOEN; //enable clock for alternate functions
RCC->APB2ENR |= RCC_APB2ENR_SPI1EN; //enable clock for SPI1

GPIO 设置这些是我自定义的功能，它们工作正常

//GPIO pin setup as alternate function
pin_mode(IOPA, GPIOA, 7, op_50MHz, op_afpp);    //MOSI pin as GPIO alternate_pin can run upto 50MHz
pin_mode(IOPA, GPIOA, 6, ip, ip_pupd);  //MISO pin as GPIO alternate_pin can run upto 50MHz
pin_mode(IOPA, GPIOA, 5, op_50MHz, op_afpp);    //SCK pin as GPIO alternate_pin can run upto 50MHz
pin_mode(IOPA, GPIOA, 4, op_50MHz, op_gppp);    //CS pin as GPIO general_puspose_pin can run upto 50MHz

SPI 设置

SPI1->CR1 |= SPI_CR1_MSTR;  //master mode
SPI1->CR1 |= SPI_CR1_BR_0 | SPI_CR1_BR_1 | SPI_CR1_BR_2;    //at 571Kbps, max 31Mbps
SPI1->CR1 |= SPI_CR1_SSI;   //Software slave management enabled
SPI1->CR2 |= SPI_CR2_SSOE;  //SS o/p enable
SPI1->CR1 |= SPI_CR1_SPE;   //turn on the SPI

我被困在这里

uint8_t SPI_read_uint8_t(uint8_t addr){
    uint8_t reg_val;
    //sending the read command first along with address where we are reading from
    delay_us(50);
    digital_writepin(GPIOA, 4, LOW);
    SPI1->DR = (R_REGISTER | addr);  //sending the R_REGISTER command along with address
    while( (SPI1->SR) & (SPI_SR_BSY) );

    //please help here, how do I read the Register data from MISO pin  

Answer 1

uint8_t spi_read_write(uint8_t data)
{
    while(SPI1 -> SR & SPI_SR_RXNE) (void)*(volatile uint8_t *)&SPI1 -> DR;   //clean the FIFO
    *(volatile uint8_t *)&SPI1 -> DR = data;
    while(!(SPI1 -> SR & SPI_SR_RXNE));
    return *(volatile uint8_t *)&SPI1 -> DR;
}

uint8_t youroperation(uint8_t command, uint16_t *data)
{
    uint8_t status;
    setCSLine();
    status = spi_read_write(command);
    *data = spi_read_write(0);
    *data |= ((uint16_t)spi_read_write(0)) << 8;
    clearCSLine();   
    return status
}

youroperation将返回Sn状态寄存器command参数表示Cn命令位data将包含 Dx 数据位

要从 SPI 从机读取数据，您需要发送虚拟字节，因为主机为从机提供时钟。