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