Intel LPCI-7200S manual 5.16 7200FreeDBDMAMem, 5.17 7200DIDMAStart, @ Return Code, @ Description

denotes the actual size of allocated memory for each half of circular buffer.

@ Return Code

ERR_NoError

ERR_SmallerDMAMemAllocated

5.16 _7200_Free_DBDMA_Mem

@ Description

Releases a system’s circular buffer DMA memory. This function is only available in Windows 95/98. For double-buffered transfer principle, please refer to Section 6 “Double Buffered Mode Principle”.

@ Syntax

Visual C++ (Windows 95)

int W_7200_Free_DBDMA_Mem (U32 handle)

Visual Basic (Windows 95)

W_7200_Free_DBDMA_Mem (ByVal handle As Long ) As Long

@ Argument

handle: The handle of system DMA memory to release.

@ Return Code

ERR_NoError

5.17 _7200_DI_DMA_Start

@ Description

The function will perform digital input N times with DMA data transfer by using one of the following four sampling modes:

1.pacer trigger (internal timer trigger)

2.external rising edge I_REQ

3.external falling edge I_REQ

4.I_REQ & I_ACK handshaking

It will take place in the background which will not stop until the Nth input data is transferred or your program execute _7200_DI_DMA_Stop function to stop the process.

After executing this function, it is necessary to check the status of the operation by using the function _7200_DI_DMA_Status. The PCI-7200 Bus mastering DMA is different from traditional PC style DMA. Its description is as follows:

C/C++ Libraries • 47