Zilog Z80180 - Manual (Page 126)

Z8018x
Family MPU User Manual
UM005003-0703
111
2. Specify memory « I/O transfer mode and address increment/
decrement in the SM0, SM1, DM0 and DM1 bits of DMODE.
3. Load the number of bytes to transfer in BCR0
4. The DMA request sense mode (DMS0 bit in DCNTL) must be
specified as edge sense.
5. Enable or disable DMA termination interrupt with the DIE0 bit in
DSTAT.
6. Program DE0 =
1
(with DWE0 =
0
in the same access) in DSTAT and
the DMA operation with the ASCI begins under control of the ASCI
generated internal DMA request.
The ASCI receiver or transmitter using DMA is initialized to allow the
first DMA transfer to begin.
The ASCI receiver must be empty as shown by RDRF =
0
.
The ASCI transmitter must be full as shown by TDRE = 0. Thus, the first
byte is written to the ASCI Transmit Data Register under program
control. The remaining bytes are transferred using DMA.
Channel 1 DMA
DMAC Channel 1 performs memory to/from I/O transfers. Except for
different registers and status/control bits, operation is exactly the same as
described for channel 0 memory to/from I/O DMA.
To initiate a DMA channel 1 memory to/from I/O transfer, perform the
following operations:
1. Load the memory address (20 bits) into MAR1.
2. Load the I/O address (16 bits) into IAR1.
3. Program the source/destination and address increment/decrement
mode using the DIM1 and DIM0 bits in DCNTL.