Z80180 Datasheet, PDF (121/326 Pages) Zilog, Inc. – Z8018x Family MPU

Z 8018x Fam ily
M PU Us e r M anual
106
DMA cycle _{CPU cycle DMA cycle (transfer 1 byte) CPU cycle DMA cycle}
Phi
Address
T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2
LD g,m
Op Code
address
Source
memory
address
Destination
memory
address
LD g,m
operand
address
MREQ
RD
WR
Data
m
Read data Write data,
m
Figure 46. DMA Timing Diagram-CYCLE STEAL Mode
To initiate memory to/from memory DMA transfer for channel 0, perform
the following operations.
1. Load the memory source and destination address into SAR0 and DAR0
2. Specify memory to/from memory 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. Specify burst or cycle steal mode in the MMOD bit of DCNTL.
5. Program DE0 = 1 (with DWE0 = 0 in the same access) in DSTAT
and the DMA operation starts one machine cycle later. If interrupt
occurs at the same time, the DIE0 bit must be set to 1.
UM005001-ZMP0400