SPI通信，如何正确设置时钟

Question

我们正在尝试在pic32和ADS1298之间建立SPI通信。问题是我们无法正确设置时钟。

我试过的是以下内容

#include <xc.h>
#include "SDlib16.h"
#pragma config FNOSC = FRCPLL // Oscillator selection
#pragma config POSCMOD = HS // Primary oscillator mode
#pragma config FPLLIDIV = DIV_2 // PLL input divider (8 -> 4)
#pragma config FPLLMUL = MUL_20 // PLL multiplier  ( 4x20 = 80)
#pragma config FPLLODIV = DIV_1 // PLL output divider
#pragma config FPBDIV = DIV_2 // Peripheral bus clock divider 80/ 2= 40 mhz
#pragma config FSOSCEN = OFF // Secondary oscillator enable

#pragma config IESO=OFF 
#pragma config FCKSM=CSDCMD
#pragma config OSCIOFNC=OFF

#pragma config FWDTEN = OFF // Watchdog timer enable
#pragma config WDTPS = PS4096 // Watchdog timer post-scaler
#pragma config FSRSSEL = PRIORITY_7 // SRS interrupt priority


/*
 * 
 */
void configpins(void)
{
    DDPCONbits.JTAGEN = 0;//Turns off the JTAG function of  all pins
    AD1PCFG=0xFFFF;//Turns off the analog function of all pins
    TRISBbits.TRISB8=0; //Makes RB8 an output (Chip select)
    TRISBbits.TRISB12=0;//Makes RB12 an output(Hold)
    TRISBbits.TRISB10=0;//Makes RB10 an output(Write protect)
}
void initialSPI(void)
{
    IEC0CLR=0x03800000;//turns off SPI interrupts 
    SPI4CONbits.ON=0;//turns off SPI4 module
    SPI4BUF=0;//Sets SPI4 buffer to 0
    SPI4CONbits.ENHBUF=0;//Sets ENHBUF to zero
    SPI4CONbits.CKP=0;//Sets clock phase bit to 0
    SPI4BRG=0;//Sets the SPI clock to be at 20MHz(Logic analyzer cant sample high enough for 20MHz )
    SPI4STATbits.SPIROV=0;//Sets overflow bit to zero
    SPI4CONbits.MSTEN=1;//Sets microcontroller to master mode
    SPI4CONbits.DISSDO=0;//Sets the module to control the SDO pin
    SPI4CONbits.CKE=1;//Sets the clock edge bit to 1
    SPI4CONbits.SMP=0;//Sets SMP bit to 0

    SPI4CONbits.MODE16=0;//Turns off 16bit mode
    SPI4CONbits.MODE32=0;//Turns off 32bit mode
    SPI4CONbits.ON=1;// Turns on SPI4 module

}
unsigned char Transfer(unsigned char data)
{   
    SPI4STATbits.SPIRBF=0; //Clears the receives buffer bit 
    SPI4BUF = data;//Puts data into the buffer
    SPI4STATbits.SPITBE=0;//Turns off buffer enable 
    while (!SPI4STATbits.SPIRBF);//While the Receive buffer flag is empty
    return SPI4BUF; // read a byte

}

unsigned char SPITransaction(unsigned char data)//Simple one byte in and one out
{
    PORTBbits.RB8=0;//clears the chip select
    unsigned char CharReturned=Transfer(data);// Calls the transfer function to send byte to buffer
    PORTBbits.RB8=1;//Sets the chip select
    return CharReturned;//Returns the byte received from buffer

}
void ReadDevice(void)//Gets the Device ID
{
    PORTBbits.RB8=0;//Clears the chip select
    Transfer(0xAB);//Bytes to get the device id
    Transfer(0x00);
    Transfer(0x00);
    Transfer(0x00);
    Transfer(0x00);
    Transfer(0x00);
    PORTBbits.RB8=1;//Sets the Device ID
}
int main(int argc, char** argv) 
{
    configpins();
    initialSPI();
    PORTBbits.RB10=1;//Sets the Write protect to high
    PORTBbits.RB12=1;//Sets Hold to high
    PORTBbits.RB0=0;
    while(1)// Forever loop
    {
     //unsigned char Result=SPITransaction('W');//Sends W to the buffer and gets back a byte
     //ReadDevice();//Gets the Device ID
    PORTBbits.RB8=0;//Clears the chip select
    Transfer(0x08);//Bytes to get the device id
    PORTBbits.RB8=1;//Sets the Device ID
    }
    return (EXIT_SUCCESS);
}

我不知道我做错了什么，当我将时钟连接到逻辑分析仪时，它看起来不像时钟，相反它看起来像一个完全随机的人都知道我做错了什么？

Answer 1

我想你错过了将SCK（时钟）设置为输出。