Z8S180 Zilog., Z8S180 Datasheet - Page 124

• Manufacturer Part Number: Z8S180
• Description: ENHANCED Z180 MICROPROCESSOR
• Manufacturer: Zilog.

memory mapped I/O. transfers, the CKA0/ DREQ0 pin automatically
functions as input pin or output pin even if it has been programmed as
output pin for CKA0. And the CKA1/ TEND0 pin functions as an input or
an output pin for TEND0 by setting CKA1D to 1 in CNTLA1.
To initiate memory to/from I/O (and memory to/from memory mapped
I/O) DMA transfer for channel 0, perform the following operations:
1. Load the memory and I/O or memory mapped I/O source and
2. Specify memory to/from I/O or memory to/from memory mapped I/O
3. Load the number of bytes to transfer in BCR0.
4. Specify whether DREQ0 is edge- or level-sense by programming the
5. Enable or disable DMA termination interrupt with the DIE0 bit in
6. Program DE0: = 1 (with DWEO = 0 in the same access) in DSTAT
Memory to ASCI - Channel 0
Channel 0 has extra capability to support DMA transfer to/from the on-
chip two channel ASCI. In this case, the external DREQ0 input is not
used for DMA timing. Rather, the ASCI status bits are used to generate an
internal DREQ0 The TDRE (Transmit Data Register Empty) bit and the
RDRF (Receive Data Register Full) bit are used to generate an internal
destination addresses into SAR0 and DAR0.
I/O addresses (not memory mapped I/O are limited to 16 bits (A0–
A15). Make sure that bits A16, A17 and A19 are
care) to correctly enable the external DREQ0 input.
mode and address increment/decrement in the SM0, SM1, DM0 and
DM1 bits of DMODE.
DMS0 bit of DCNTL.
DSTAT.
and the DMA operation begins under the control of the DREQ0 input.
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