TMP91C824
91C824-87
3.6.3
Connecting external memory
Figure 3.6.6 shows an example of how to connect external memory to the TMP91C824.
In this example the ROM is connected using a 16-bit bus. The RAM and I/O are connected using an 8-bit
bus.
Address bus
___
CS
8-bit
RAM
___
OE
___
WE
TMP91C824
〜
〜
___
CS
Upper byte
ROM
___
OE
___
CS
Lower byte
ROM
___
OE
___
CS
8-bit
I/O
___
OE
___
WE
____
CS0
____
CS1
____
CS2
A0
A23
D8
D15
D0
D7
___
RD
___
WR
〜
Figure 3.6.6 Example of external memory connection
(ROM uses 16-bit bus; RAM and I/O use 8-bit bus.)
A Reset clears all bits of the Port 6 Control Register P6CR and the Port 6 Function Register P6FC to
“0” and disables output of the CS signal. To output the CS signal, the appropriate bit must be set to “1”.
Figure 3.6.7 Example of external memory connection (RAM and I/O use 16-bit bus)
OE
LDS
UDS
R/W
CE
I/O [16:1]
A0
A1
A2
RD
WR
HWR
R/W
CS0
D [15:0]
A0
A1
A2
A3
TMP91C824F 16-bit
SRAM