adc-44d ETC-unknow, adc-44d Datasheet - Page 65

• Manufacturer Part Number: adc-44d
• Description: Multi-function Analogue Input/output Card
• Manufacturer: ETC-unknow

Appendix C
DMA Limitations
The DMA controller is only capable of incrementing or decrementing the
DMAOFFSET address, the DMAPAGE value is fixed throughout the transfer.
This means that a maximum of 64K bytes can be transferred in one operation.
Programming Example
To set-up a DMA transfer the following program sequence is required:
The extract from a QUICK BASIC program on the following page demonstrates
how to program the DMA controller for a WRITE transfer.
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Define an area of memory for the transfer
Set-up the I/O board for DMA operation
Disable the DMA channel being used.
Load the start address into PAGE register. This is the START address
register for the DMA channel being used.
Load the length count into the TRANSFER LENGTH register. Note that the
DMA controller only transfers 8 bits at a time, each value written to an
ANALOGUE OUT board or read from an ANALOGUE IN board is 2 bytes
long so the transfer length will be twice the number of samples to be taken.
Load the mode for the selected DMA channel.
Enable the DMA channel.
How to Use DMA
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