[Raspberry] 在Raspberry Pi 2 使用SPI

在 C library for Broadcom BCM 2835 as used in Raspberry Pi 提及:

in order for bcm2835 library SPI to work, you may need to disable the SPI kernel module using:

sudo raspi-config

under Advanced Options - enable Device Tree

under Advanced Options - disable SPI

Reboot.

所以我就跟著做了…..

程式:

#include <cstdlib>

#include <bcm2835.h>

#include <unistd.h>

#include <stdio.h>

using namespace std;

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

    bcm2835_init();

   

    //setup spi pins

    if(bcm2835_spi_begin()==0)

    {

        printf("init failed \r\n");

        return -1;

    }

   

    //set CS pins polarity to low

    bcm2835_spi_setChipSelectPolarity(BCM2835_SPI_CS0,0);

    bcm2835_spi_setChipSelectPolarity(BCM2835_SPI_CS1,0);

  

    //set clock speed

    bcm2835_spi_setClockDivider(BCM2835_SPI_CLOCK_DIVIDER_32768);

   

    //set SPI data mode

    bcm2835_spi_setDataMode(BCM2835_SPI_MODE0);

   

   

    //Set with CS pin to use for next transfers

    bcm2835_spi_chipSelect(BCM2835_SPI_CS0);

   

    //transfer  byte

    char buf[100];

    for(int j=0;j<100;j++)

    {

        buf[j]=0x55;

    }

    for(int j=0;j<10;j++)

    {

     bcm2835_spi_transfern(&buf[0],100);

    

     bcm2835_delay(1000);

    }

  

    //return spi pins to default input state

    bcm2835_spi_end();

    return 0;

}

從示波器上,發現只有j=0才會有CLK,其他時間CLK都不見(是否是因為沒接裝置沒有正常回應…)...不知勒