以下是我用C8051F330SPI模块做的从机程序。采用的是空闲时高电平，上升沿采样的模式。但是当我和相应主机通信时，在MISO上却始终是高电平，从机不能正常发送数据。困扰好久，求大侠给点指点，万分感激
以下是代码
//-----------------------------------------------------------------------------
// F33x_SPI0_Slave.c
//-----------------------------------------------------------------------------
// Copyright 2006 Silicon Laboratories, Inc.
// http://www.silabs.com
//
// Program Description:
//
// This program configures a C8051F33x as a SPI Slave. The 'F33x MCU
// is configured in 4-wire Slave Mode.
//
// This example is intended to be used with the SPI0_Master example.
//
// Pinout:
//
// P0.0 - SPI SCK (digital input, open-drain)
// P0.1 - SPI MISO (digital output, push-pull)
// P0.2 - SPI MOSI (digital input, open-drain)
// P0.3 - SPI NSS (digital input, open-drain)
//
// P1.3 - LED (digital output, push-pull)
//
// all other port pins unused.
//
//
// How To Test:
//
// 1) Download the code to a F330-TB that is connected as above to
// another device running the SPI0_Master code.
// 2) Verify that the J6 jumper is not populated.
// 3) Verify the LED pins of jumper J3 are populated.
// 4) Run the code.
// 5) If the communication passes, the LEDs on both the Master and Slave
// boards will blink slowly. If it fails, the LEDs will be OFF.
//
// Target: C8051F33x
// Tool chain: Keil C51 7.50 / Keil EVAL C51
// Command Line: None
//
// Release 1.0
// -Initial Revision (TP)
// -12 DEC 2006
//
//-----------------------------------------------------------------------------
// Includes
//-----------------------------------------------------------------------------
#include <C8051F330.h> // SFR declarations
//-----------------------------------------------------------------------------
// Global Constants
//-----------------------------------------------------------------------------
#define SYSCLK 24500000 // Internal oscillator frequency in Hz
#define MAX_BUFFER_SIZE 8 // Maximum buffer Master will send
// Instruction Set
#define SLAVE_LED_ON 0x01 // Turn the Slave LED on
#define SLAVE_LED_OFF 0x02 // Turn the Slave LED off
#define SPI_WRITE 0x04 // Send a byte from the Master to the
// Slave
#define SPI_READ 0x08 // Send a byte from the Slave to the
// Master
#define SPI_WRITE_BUFFER 0x10 // Send a series of bytes from the
// Master to the Slave
#define SPI_READ_BUFFER 0x20 // Send a series of bytes from the Slave
// to the Master
#define ERROR_OCCURRED 0x40 // Indicator for the Slave to tell the
// Master an error occurred
sbit LED = P1^3; // LED='1' means ON
//-----------------------------------------------------------------------------
// Global Variables
//-----------------------------------------------------------------------------
unsigned char SPI_Data = 0xA5;
unsigned char SPI_Data_Array[MAX_BUFFER_SIZE] = {0};
unsigned char SLAVE_code[]={
0x8e,0x8e,0xde,0x8e,0xd,0x8e,0x0,0x8e,0x11,0x8e,0x3f,0x20,0x0,0x8e,0x0,0x38,0x0,0x0,0x0,0x8e,0x91,
0x8e,0x2b,0x2b,0x0,0x8e,0x2,0x8e,0x5d,0x8e,0x0,0x0,0x0,0x0,0x53,0x49,0x5c,0xf,0x0,0x0,0x0,0x8e,0x3f,
0x20,0x0,0x8e,0x0,0x38,0x0,0x0,0x0,0x8e,0x8,0x3,0x0,0x8e,0x91
};
int receiveIndex = 0;
int sendIndex = 0;
//-----------------------------------------------------------------------------
// Function Prototypes
//-----------------------------------------------------------------------------
void PCA0_Init (void);
void Oscillator_Init (void);
void Port_Init (void);
void SPI0_Init (void);
void Init_Device (void);
//-----------------------------------------------------------------------------
// main() Routine
//-----------------------------------------------------------------------------
void main (void)
{
Init_Device (); // Initializes hardware peripherals
EA = 1; // Enable global interrupts
LED = 0;
while (1); // Loop forever
}
//-----------------------------------------------------------------------------
// Initialization Subroutines
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
// PCA0_Init
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters : None
//
// This function disables the watchdog timer.
//
//-----------------------------------------------------------------------------
void PCA0_Init (void)
{
PCA0MD &= ~0x40; // Disable the Watchdog Timer
PCA0MD = 0x00;
}
//-----------------------------------------------------------------------------
// Oscillator_Init
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters : None
//
// This function initializes the system clock to use the internal oscillator
// at 24.5 MHz.
//
//-----------------------------------------------------------------------------
void Oscillator_Init (void)
{
OSCICN = 0x83; // Set the internal oscillator to
// 24.5 MHz
}
//-----------------------------------------------------------------------------
// Port_Init
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters : None
//
// This function configures the crossbar and GPIO ports.
//
// P0.0 - SCK (SPI0), Open-Drain, Digital
// P0.1 - MISO (SPI0), Push-Pull, Digital
// P0.2 - MOSI (SPI0), Open-Drain, Digital
// P0.3 - NSS (SPI0), Open-Drain, Digital
//
// P1.3 - Skipped, Push-Pull, Digital (LED D2 on Target Board)
//
//-----------------------------------------------------------------------------
void PORT_Init (void)
{
P0MDOUT = 0x02; // Make MISO push-pull
P1MDOUT = 0x08; // Make the LED push-pull
P1SKIP = 0x08; // Skip the LED (P1.3)
XBR0 = 0x02; // Enable the SPI on the XBAR
XBR1 = 0x40; // Enable the XBAR and weak pull-ups
}
//-----------------------------------------------------------------------------
// SPI0_Init
//-----------------------------------------------------------------------------
void SPI0_Init()
{
SPI0CFG = 0x30; //3-wire slave mode. SCK line high in idle state.raising edge sampling
SPI0CN = 0x01;
SPI0DAT = 0x8e;
ESPI0 = 1; // Enable SPI interrupts
}
//-----------------------------------------------------------------------------
// Init_Device
//-----------------------------------------------------------------------------
void Init_Device (void)
{
PCA0_Init (); // Disable the Watchdog Timer first
Oscillator_Init ();
Port_Init ();
SPI0_Init ();
}
//-----------------------------------------------------------------------------
// SPI_ISR
//-----------------------------------------------------------------------------
void SPI_ISR (void) interrupt 6
{
// static unsigned char command;
// static unsigned char array_index = 0;
// static unsigned char state = 0;
// unsigned char dummy_byte;
// Write collision occurred
WCOL = 0;
// SPI0DAT = ERROR_OCCURRED; // Indicate an error occurred
// SPI0DAT = ERROR_OCCURRED; // Indicate an error occurred
RXOVRN = 0; // Clear the Receive Overrun flag
SPI_Data_Array[receiveIndex++] = SPI0DAT;
SPI0DAT = SLAVE_code[sendIndex++];
if(receiveIndex>=MAX_BUFFER_SIZE)
receiveIndex = 0;
if(sendIndex>=sizeof(SLAVE_code))
receiveIndex = 0;
SPIF = 0;
}
检查硬件及寄存器配件
P0端口交叉开关，分配的不对，即便是特殊功能脚，也应该输出分配一，输入分配0