[Raspberry] 在Raspberry Pi 2 使用SPI(一)

先 Enable SPI Kernel Module

ls /dev 會看到有 spidev0.0 及 spidev0.1

程式::

#include <cstdlib>

#include <stdio.h>

#include <fcntl.h>

#include <sys/ioctl.h>

#include <linux/spi/spidev.h>

#include <unistd.h>

#include <string.h>

using namespace std;

int spi_cs0_fd;

unsigned char spi_mode;

unsigned char spi_bitsPerWord;

unsigned int spi_speed;

int spiOpenPort()

{

    int *spi_cs_fd;

   

    int status_value=-1;

   

    spi_mode=SPI_MODE_0;

    spi_bitsPerWord=8;

    spi_speed=1000000;

   

    spi_cs_fd=&spi_cs0_fd;

   

    *spi_cs_fd=open("/dev/spidev0.0",O_RDWR);

   

    if(*spi_cs_fd<0)

    {

        printf("Open /dev/spidev0.0 failed\r\n");

        exit(1);

    }

   

    status_value=ioctl(*spi_cs_fd,SPI_IOC_WR_MODE,&spi_mode);

    if(status_value<0)

    {

        printf("W spi_mode failed\r\n");

        exit(1);

    }

   

    status_value=ioctl(*spi_cs_fd,SPI_IOC_RD_MODE,&spi_mode);

    if(status_value<0)

    {

        printf("RD spi_mode failed\r\n");

        exit(1);

    }

   

    status_value=ioctl(*spi_cs_fd,SPI_IOC_WR_BITS_PER_WORD,&spi_bitsPerWord);

    if(status_value<0)

    {

        printf("WR sp_bitsPerWord failed\r\n");

        exit(1);

    }

   

    status_value=ioctl(*spi_cs_fd,SPI_IOC_RD_BITS_PER_WORD,&spi_bitsPerWord);

    if(status_value<0)

    {

        printf("RD sp_bitsPerWord failed\r\n");

        exit(1);

    }

   

    status_value=ioctl(*spi_cs_fd,SPI_IOC_WR_MAX_SPEED_HZ,&spi_speed);

    if(status_value<0)

    {

        printf("WR spi_spped failed\r\n");

        exit(1);

    }

       

    status_value=ioctl(*spi_cs_fd,SPI_IOC_RD_MAX_SPEED_HZ,&spi_speed);

    if(status_value<0)

    {

        printf("RD spi_spped failed\r\n");

        exit(1);

    }

         

    return(status_value);   

}

int SpiWriteAndRead(unsigned char *data,int length)

{

    struct spi_ioc_transfer spi[length];

    int i=0;

    int retVal =-1;

    int *spi_cs_fd;

   

    spi_cs_fd=&spi_cs0_fd;

   

    for(i=0;i<length;i++)

    {

        memset(&spi[i],0,sizeof(spi[i]));

        spi[i].tx_buf=(unsigned long)(data+i);

        spi[i].rx_buf=(unsigned long)(data+i);

        spi[i].len=sizeof(*(data+i));

        spi[i].delay_usecs=0;

        spi[i].speed_hz=spi_speed;

        spi[i].bits_per_word=spi_bitsPerWord;

        spi[i].cs_change=0;

    }

   

    retVal=ioctl(*spi_cs_fd,SPI_IOC_MESSAGE(length),&spi);

   

    if(retVal<0)

    {

        printf("tran error \n\r");

        exit(1);

    }

    return retVal;  

}

int main(int argc, char** argv) {

    unsigned char buffer[100];

   

    for(int j=0;j<100;j++)buffer[j]=0x55;

   

    if(spiOpenPort()<0)

    {

        return -1;

    }

    SpiWriteAndRead(buffer,100);

   

    close(spi_cs0_fd);

   

    return 0;

}

 參考資料:

Using the SPI Interface

http://www.raspberry-projects.com/pi/programming-in-c/spi/using-the-spi-interface

C library for Broadcom BCM 2835 as used in Raspberry Pi

http://www.airspayce.com/mikem/bcm2835/

Interfacing an SPI ADC(MCP3008) chip to Raspberry Pi using C++(spidev)

http://www.hertaville.com/interfacing-an-spi-adc-mcp3008-chip-to-the-raspberry-pi-using-c.html