Texas Instruments TMS320C3x - Manual (Page 337)

8-Bit-Wide Memory Interface
10-34
Case 8: 8-Bit Wide Memory With 16-Bit Data-Type Size
When the data-type size is 16 bits, the ‘C32 shifts the internal address one bit
to the right before presenting it to the external-address pins. In this shift, the
memory interface copies the value of the internal-address A
23
to the external-
address pins A
23
and A
22
. Also, the memory interface copies the value of the
internal-address A
0
to the external STRBx_B3 / A
–1
pin. Furthermore, the
memory interface toggles STRBx_B2 / A
–2
twice to perform two 8-bit memory
accesses. Moreover, the memory interface activates the STRBx_B0 during
accesses. In summary, the memory interface adds one wait state to the 16-bit
data access. Figure 10–20 shows a functional diagram of the memory inter-
face for 8-bit-wide memory with 16-bit data-type size.
Figure 10–20. Functional Diagram for 16-Bit Data-Type Size and 8-Bit External-Memory
Width
A
24
A
23
A
22
A
21
.
.
.
A
3
A
2
A
1
A
0
CS
I/O(7–0)
’C32
A
23
A
22
A
21
A
20
A
19
.
.
.
A
1
A
0
STRBx_B3/A
-1
STRBx_B2/A
-2
STRBx_B0
D(7–0)
A
23
A
22
A
21
A
20
.
.
.
A
2
A
1
A
0
Memory interface
toggle
’C32’
s core address bus
STRBx
logic