IPC@CHIP Documentation - SC12 @CHIP-RTOS V1.10

Starts the DMA mode. After calling this function, the DMA transfer will be started when the external
DRQ pins is activated.
Parameters
AH
AL
CX
DX
BX:SI
ES:DI
Must be 0xB0
DMA channel:
0 = DRQ0
1 = DRQ1
Number of bytes which has to be transferred
Control Register:
Bit 0: 1=Priority for the channel / 0=Priority for the other channel
Bit 1: 1=Source synchronized / 0=No source synchronization
Bit 2: 1=Destination synchronized / 0=No destination synchronization
Bit 3: 1=Use interrupt at end of transfer / 0=do not use an interrupt
Bit 4: must be set to '1'
Bit 5: 1=Source address increment / 0=No increment of source address
Bit 6: 1=Source address decrement / 0=No decrement of source Address
Bit 7: 1=Source is in memory space / 0=Source is in IO space
Bit 8: 1=Destination address increment / 0=No increment of destination address
Bit 9: 1=Destination address decrement / 0=No decrement of destination address
Bit 10: 1=Destination is in memory space / 0=Destination is in IO space
Bit 11: 1=Word Transfer / 0=Byte Transfer
Bit1 and Bit2 can't be set at the same time.
Pointer to unsigned long (20-Bit physical) source address
Pointer to unsigned long (20-Bit physical) destination address
Return Value
Comments
Success: AX = 0
AX = -1 Invalid DMA channel
AX = -2 DMA channel used for serial interface
This function starts a DMA transfer. After calling this function the DMA controller is ready for transfer.
Once the DRQ pin is activated the DMA transfer will be started. The number of bytes which will be
transferred has to be specified in the CX register. Before calling this function you have to enable the
DRQ pin for this channel (also the serial DMA mode must be disabled in the CHIP.INI).
Related Topics
Enable external DRQ Pin
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