PCA上升沿捕捉与T2定时器1S应用示例

//-----------------------------------------------------------------------------
// F34x_PCA0_Capture_Input.c
//-----------------------------------------------------------------------------
// Copyright 2006 Silicon Laboratories, Inc.
// http://www.silabs.com
//
// Program Description:
//
// This program uses the PCA's capture mode to time events on an input pin.
// The difference between subsequent captures is calculated and stored in
// memory.
//
// In this example, PCA Module 0 is used to capture rising edges of an
// incoming digital waveform, and the crossbar is configured to receive the
// CEX0 pin on on P0.0.  The PCA is configured to clock once every 10 us.
//
// Timer2 overflows are used to toggle pin P0.1 at an overflow rate specified
// by the definition T2_RELOAD_CLOCKS. This signal at P0.1 is provided simply
// as a test method for the code.
//
// How To Test:
//
// 1) Download code to a 'F34x device with P0.0 and P0.1 tied together.
// 2) Run the program for a few seconds, and then halt.
// 3) Verify that the variable "capture_period" is equal to 50 (=500us).
//
// Alternately:
// 1) Run a separate signal generator into the P0.0 pin.
// 2) Run the program for a few seconds, and then halt.
// 3) Verify that the variable "capture_period" matches the expected time

//    between rising edges (in units of 10us).
//
//
// FID:            34X000091
// Target:         C8051F34x
// Tool chain:     Keil C51 8.00 / Keil EVAL C51
// Command Line:   None
//
//
// Release 1.0
//    -Initial Revision (BD)
//    -21 AUG 2006
//

//PCA捕捉模式, 模块0上升沿捕捉,CEX0- P0.0. LED1 显示进入捕捉中断 The PCA is configured to clock once every 10 us.
//-----------------------------------------------------------------------------
// Includes
//-----------------------------------------------------------------------------

#include <c8051f340.h>                 // SFR declarations


//-----------------------------------------------------------------------------
// Global Constants
//-----------------------------------------------------------------------------

#define SYSCLK       12000000          // Internal oscillator frequency in Hz

#define T0_CLOCKS 120                  // Use 120 clocks per T0 Overflow
                                       //    (120 = 10 us)