哪位大侠帮忙！？我现在需要在DOS下利用PCI7200来采集数据，设置count=2000,采用单次DMA方式，可是采集到的数据却只有100多个，返回的currentCount最多只有104，为什么？ 　　是不是需要配置还是我的程序有问题？我是利用\dos_bc\samples\di_demo2.c例程改写的，只是将原来的输入_7200_do()去掉，然后由FPGA输出数据，采用I_req&I_ack握手方式，不知是否有问题？FPGA发出的I_req信号为3us,即使我将模式改为外部时钟触发，也不能获得我所需要的数据，不知道怎么办，希望高人指点，下面是我的源程序： #include <conio.h> #include <stdio.h> #include <stdlib.h> #include <dos.h> #include <\sys\stat.h> #include "acl.h" #include "aclerr.h" #include "std.h" #include "video.h" #include "key.h" #include "7200.H" #pragma(4) #define ACL_TitleColor (WHITE | bgcolor(GREEN)) #define ACL_TextColor (WHITE | bgcolor(BLUE)) #define ACL_BkColor (BLUE | bgcolor(BLUE)) /* background color */ #define ACL_MsgColor (RED|INVERSE) #define ACL_ProgColor (WHITE | bgcolor(BROWN)) #define DI_DB_COUNT 1000 /* double buffer count */ #define DI_SAMPLE_COUNT (DI_DB_COUNT * 2) #define DI_DB_ENABLE 1 /* double duffer mode enable */ #define DI_DB_DISABLE 0 /* double duffer mode disable */ std_UByte *acl_Title = "****** PCI-7200 DI DEMO (continue DMA)"; std_UByte *acl_Copyright="Copyright (c) 1995-1999, ADLink Technology Inc. All rights reserved."; std_UByte *msg1 = "Program : DI_DEMO3.C"; std_UByte *msg2 = "Function: continue read digital input data throught DMA (Bus Master)"; std_UByte *msg3 = " using double buffer mode to receive data"; U32 *diDmaDwPtr; /* double word boundary pointer */ U8 *charPtr; U32 diDmaBuf[DI_SAMPLE_COUNT+1]; /* +1 for double word alignment adjusting */ U32 userBuf[DI_DB_COUNT]; Boolean clear_fifo=FALSE, disable_di=FALSE; /*----------------------------------------------------------------------*/ void showMessage(std_UByte *msg) { video_ClearBox(24, 0, 24, 79, INVERSE); video_CenterPutStr(24, msg, ACL_MsgColor); } /*----------------------------------------------------------------------*/ void main( void ) { int i, j, h, handle, x1, y1, err, status, timerMode; U32 readyCnt; char tmpBuf[80]; Boolean readyFlag; U16 c0, c1, c2; U32 dest; U8 irqNo; /* interrupt line number, assigned by system */ U16 baseAddr; /* base address, assigned by system */ U32 currentCount; /* current count of DMA read for DI */ U32 overrunCnt; /*---------- PCI-7200 initial ------------------------------------------*/ if( (err =_7200_Initial(CARD_1, &baseAddr, &irqNo)) != ERR_NoError ) { printf("No PCI-7200 card found !!\n"); exit(0); } /*----------------------------------------------------------------------*/ video_Initial(); video_CursorOff(); video_Box(VIDEO_SINGLE, 0, 0, 4, 79, ACL_TitleColor); video_Box(VIDEO_DOUBLE, 5, 0, 23, 79, ACL_TextColor); video_ClearBox(24, 0, 24, 79, INVERSE | BLUE); sprintf(tmpBuf,"%s, Address = %X IRQ = %d ******", acl_Title, baseAddr, (unsigned char)irqNo); video_CenterPutStr(1, tmpBuf, ACL_TitleColor); video_CenterPutStr(3, acl_Copyright, ACL_TitleColor); video_PutStr(6, 5, msg1, ACL_ProgColor); video_PutStr(7, 5, msg2, ACL_ProgColor); video_PutStr(8, 5, msg3, ACL_ProgColor); showMessage(">>> Press any key to start the operation <<<"); getch(); /* double word alignment adjusting */ dest = ((U32) FP_SEG(diDmaBuf))*16 + FP_OFF(diDmaBuf); charPtr = (char *) diDmaBuf; diDmaDwPtr = (U32 *) (charPtr + (dest & 0x03L)); _7200_DblBufferMode(DI_DB_ENABLE); getch(); /*;;;;;;;;;;;;;;;;;;;;; Setup the DMA for DI ;;;;;;;;;;;;;;;;;;;;;;;*/ if( _7200_DI_DMA_Start(DI_MODE_3, DI_SAMPLE_COUNT, diDmaDwPtr, DI_WAITING, DI_RISING, clear_fifo, disable_di) != ERR_NoError) { video_CursorOn(); video_ClearBox(24, 0, 24, 79, NORMAL); video_PutSt