Page 93 - Embedded Microprocessor Systems Real World Design

ADDRESS BUFFER
FOR DMA DEVlCE

l&WT ADDRESS
FROM DMA DEVICE

A2
AI
DMA 6€ -
TO AWID BUS CONTENTION. DMA MUST BE
Wlss CPU ASSERTED AFTER HLDA GOES HIGH AND
I REMOVED BEFORE HLDA GOES BACK LOW.
A12
All
A10
A8 - MICROPROCESSOR
MULTIPLEXED {g ADDRESS BUS DRIVES ALL
BUFFERED
PERIPHERALS

ADDRESSIDATA A3
BUS
AI
ADO PUUUP RES STORS PREVENT
SPURIOUS S GNUS ON
ALE -RD AND -WR SIGNALS WHILE
HIGH ON HLDA DISABLES BOTH CPU AND DMA *M
HLDA ADDRESS BUS SO DMA ME LINES TRiSTATED
DEVlCE CAN DRlM IT.
-WR TO ALL PERIPHERALS
-RD TO ALL PERIPHERALS

-WR FROM DMA CONTROLLER
-RD FROM DMA CONTROLLER -

Figure 2.23
Driving Address Bus During DMA.