1 NRF52832SPI主机的功能描述
nRF52832SPIM的主要特征
3个SPI实例
支持SPI的模式0到模式3
支持DMA
Individual selection of IO pin for each SPI signal
注意：SPI主控制器不支持直接片选，因此SPI主机的CPU必须使用可用的GPIO来实现对从机的片选控制。另外，SPI可与和它具有相同ID的其他外设共享寄存器和其他一些资源。配置和使用SPI之前必须关闭与它有相同ID的外设。关闭与SPI有相同ID的外设，不会复位与SPI共享的寄存器。因此为了确保SPI正常运行，必须配置相关的SPI寄存器。
2 软件设计
2.1

#define NRF_DRV_SPI_DEFAULT_CONFIG                           \
{                                                            \.sck_pin      = NRF_DRV_SPI_PIN_NOT_USED,                \  //SCK时钟引脚.mosi_pin     = NRF_DRV_SPI_PIN_NOT_USED,                \  //MOSI引脚.miso_pin     = NRF_DRV_SPI_PIN_NOT_USED,                \  //MISO引脚.ss_pin       = NRF_DRV_SPI_PIN_NOT_USED,                \  //SS引脚.irq_priority = SPI_DEFAULT_CONFIG_IRQ_PRIORITY,         \  //中断优先级.orc          = 0xFF,                                    \.frequency    = NRF_DRV_SPI_FREQ_4M,                     \  //SPI通信的速率.mode         = NRF_DRV_SPI_MODE_0,                      \  //SPI的工作模式.bit_order    = NRF_DRV_SPI_BIT_ORDER_MSB_FIRST,         \  //MSB先行或LSB先行
}

NRF_DRV_SPI_DEFAULT_CONFIG宏用来配置SPI的基本信息。其中SPI_DEFAULT_CONFIG_IRQ_PRIORITY用来配置SPI的中断优先级，在写程序时要注意合理的配置中断优先级，防止两个外设的中断优先级相同，在nRF52832中，中断号为0代表中断优先级最高。
2.2 代码

#include "nrf_drv_spi.h"
#include "app_util_platform.h"
#include "nrf_gpio.h"
#include "nrf_delay.h"
#include "boards.h"
#include "app_error.h"
#include <string.h>
#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"#define SPI_INSTANCE  0 /**< SPI instance index. */
static const nrf_drv_spi_t spi = NRF_DRV_SPI_INSTANCE(SPI_INSTANCE);  /**< SPI instance. */
static volatile bool spi_xfer_done;  /**< Flag used to indicate that SPI instance completed the transfer. *///#define TEST_STRING "Nordic"
//static uint8_t       m_tx_buf[] = TEST_STRING;           /**< TX buffer. */
//static uint8_t       m_rx_buf[sizeof(TEST_STRING) + 1];    /**< RX buffer. */
//static const uint8_t m_length = sizeof(m_tx_buf);        /**< Transfer length. */#define W25X_WriteEnable 0x06
#define W25X_JedecDeviceID 0X9F
#define W25X_ReadStatusReg 0x05
#define W25X_SectorErase 0xD8
#define W25X_PageProgram 0x02
#define W25X_ReadData 0x03
#define W25X_ChipErase 0xC7
#define FLASH_ID 0XEF4015  //器件ID
#define Dummy_Byte 0XFF
#define WIP_Flag  0x01#define SPI_BUFSIZE 8 //SPI缓存的大小
uint8_t   SPI_Tx_Buf[SPI_BUFSIZE];  //发送
uint8_t   SPI_Rx_Buf[SPI_BUFSIZE];  //接收
uint32_t ID = 0;
volatile  uint8_t   SPIReadLength, SPIWriteLength;
/*** @brief SPI user event handler.* @param event*/
void spi_event_handler(nrf_drv_spi_evt_t const * p_event,void *                    p_context)
{spi_xfer_done = true;
}
/*
向W25Q80中写入数据
参数 reg 寄存器地址data 要写入的数据
*/
void W25Q80_write_reg(int data)
{spi_xfer_done = false;SPIWriteLength = 1;SPIReadLength = 0;SPI_Tx_Buf[0] = data;  APP_ERROR_CHECK(nrf_drv_spi_transfer(&spi, SPI_Tx_Buf, SPIWriteLength, SPI_Rx_Buf, SPIReadLength));while(spi_xfer_done == false);
}
/*
从W25Q80中读取数据
参数： reg 寄存器地址
*/
uint8_t W25Q80_read_reg(int reg)
{spi_xfer_done = false;SPI_Tx_Buf[0] = reg;APP_ERROR_CHECK(nrf_drv_spi_transfer(&spi, SPI_Tx_Buf, 0, SPI_Rx_Buf,1));while(spi_xfer_done == false);return SPI_Rx_Buf[0];
}
/*
读取W25Q80的器件ID
*/
uint32_t W25Q80_ReadID(void)
{uint32_t temp = 0,temp0 = 0,temp1 = 0,temp2 = 0;nrf_gpio_pin_clear(SPI_SS_PIN);  //片选有效W25Q80_write_reg(W25X_JedecDeviceID);temp0 = W25Q80_read_reg(0XFF);temp1 = W25Q80_read_reg(0XFF);temp2 = W25Q80_read_reg(0XFF);nrf_gpio_pin_set(SPI_SS_PIN);  //片选无效temp = (temp0 << 16)| (temp1 << 8) | temp2;return temp;
}
/*
写使能命令
*/
void W25Q80_WriteEnable()
{nrf_gpio_pin_clear(SPI_SS_PIN);  //片选有效W25Q80_write_reg(W25X_WriteEnable);nrf_gpio_pin_set(SPI_SS_PIN);  //片选有效
}
/*
通过读状态寄存器等待FLASH芯片空闲
*/
void W25Q80_WaitForWriteEnd()
{unsigned char FLASH_Status = 0;nrf_gpio_pin_clear(SPI_SS_PIN);  //片选有效W25Q80_write_reg(W25X_ReadStatusReg); //发送读状态寄存器do{FLASH_Status = W25Q80_read_reg(Dummy_Byte);}while((WIP_Flag & FLASH_Status) == 1);nrf_gpio_pin_set(SPI_SS_PIN);  //片选无效}
/*
擦除FLASH的扇区
参数 SectorAddr 要擦除的扇区地址
*/
void W25Q80_FLASH_SectorErase(uint32_t SectorAddr)
{W25Q80_WriteEnable();  //发送FLASH写使能命令W25Q80_WaitForWriteEnd();  //等待写完成nrf_gpio_pin_clear(SPI_SS_PIN);  //片选有效W25Q80_write_reg(W25X_SectorErase);  //发送扇区擦除指令W25Q80_write_reg((SectorAddr & 0XFF0000) >> 16); //发送扇区擦除地址的高位W25Q80_write_reg((SectorAddr & 0XFF00) >> 8);W25Q80_write_reg(SectorAddr & 0XFF);nrf_gpio_pin_set(SPI_SS_PIN);  //片选无效W25Q80_WaitForWriteEnd();  //等待擦除完成
}
/*
FLASH页写入指令
参数：
备注：使用页写入指令最多可以一次向FLASH传输256个字节的数据
*/
void W25Q80_FLASH_PageWrite(unsigned char* pBuffer, uint32_t WriteAddr, uint16_t NumByteToWrite)
{W25Q80_WriteEnable();  //发送FLASH写使能命令nrf_gpio_pin_clear(SPI_SS_PIN);  //片选有效W25Q80_write_reg(W25X_PageProgram);  //发送写指令W25Q80_write_reg((WriteAddr & 0XFF0000) >> 16); //发送写地址的高位W25Q80_write_reg((WriteAddr & 0XFF00) >> 8);W25Q80_write_reg(WriteAddr & 0XFF);if(NumByteToWrite > 256){NRF_LOG_INFO("write too large!\r\n");return ;}while(NumByteToWrite--){W25Q80_write_reg(*pBuffer);pBuffer++;}nrf_gpio_pin_set(SPI_SS_PIN);  //片选无效W25Q80_WaitForWriteEnd();  //等待写完成
}
/*
从FLASH中读取数据
*/
void W25Q80_Flash_BufferRead(uint8_t* pBuffer, uint32_t ReadAddr, uint16_t NumByteToRead)
{nrf_gpio_pin_clear(SPI_SS_PIN);  //片选有效W25Q80_write_reg(W25X_ReadData);  //发送写指令W25Q80_write_reg((ReadAddr & 0XFF0000) >> 16); //发送写地址的高位W25Q80_write_reg((ReadAddr & 0XFF00) >> 8);W25Q80_write_reg(ReadAddr & 0XFF);while(NumByteToRead--){*pBuffer = W25Q80_read_reg(Dummy_Byte);pBuffer++;}nrf_gpio_pin_set(SPI_SS_PIN);  //片选无效
}
/*
全片擦除
*/
void W25Q80_Chip_Erase()
{W25Q80_WriteEnable();  //发送FLASH写使能命令nrf_gpio_pin_clear(SPI_SS_PIN);  //片选有效W25Q80_write_reg(W25X_ChipErase);  //全片擦除nrf_gpio_pin_set(SPI_SS_PIN);  //片选无效W25Q80_WaitForWriteEnd();  //等待写完成
}
void W25Q80_init()
{//初始化SPI引脚nrf_drv_spi_config_t spi_config = NRF_DRV_SPI_DEFAULT_CONFIG;
//    spi_config.ss_pin   = SPI_SS_PIN;  //把SS引脚禁用spi_config.miso_pin = SPI_MISO_PIN;spi_config.mosi_pin = SPI_MOSI_PIN;spi_config.sck_pin  = SPI_SCK_PIN;nrf_gpio_cfg_output(SPI_SS_PIN);nrf_gpio_pin_clear(SPI_SS_PIN);  //片选有效APP_ERROR_CHECK(nrf_drv_spi_init(&spi, &spi_config, spi_event_handler, NULL));nrf_delay_ms(500);nrf_gpio_pin_set(15);//读取寄存器的值，判断器件是否存在 ID=W25Q80_ReadID();if(ID != FLASH_ID){NRF_LOG_INFO("init w25q80 error\r\n");}else{NRF_LOG_INFO("init w25q80 ok!\r\n");NRF_LOG_INFO("FLASH ID is %X",ID);}
}
#define countof(a)      (sizeof(a) / sizeof(*(a)))
#define  BufferSize (countof(Tx_Buffer)-1)
int main(void)
{unsigned char Tx_Buffer[] = "This is a demo about FLASH WRITE BY Manual";unsigned char Rx_Buffer[250];bsp_board_init(BSP_INIT_LEDS);  //初始化开发板上的指示灯APP_ERROR_CHECK(NRF_LOG_INIT(NULL));NRF_LOG_DEFAULT_BACKENDS_INIT();NRF_LOG_INFO("SPI example started.");W25Q80_init();W25Q80_Chip_Erase();  //全片擦除   //全片擦除所需的时间比较长W25Q80_FLASH_PageWrite(Tx_Buffer,0x00000,BufferSize);NRF_LOG_INFO("%s\r\n",Tx_Buffer);W25Q80_Flash_BufferRead(Rx_Buffer,0x000000,BufferSize);NRF_LOG_INFO("%s\r\n",Rx_Buffer);while (1){// Reset rx buffer and transfer done flagspi_xfer_done = false;NRF_LOG_FLUSH();nrf_delay_ms(200);}
}

参考资料：
1 nRF52832数据手册
2 《低功耗蓝牙技术快速入门》
3 W25Q80数据手册
4 《零死角玩转STM32F103指南者》