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 A23 to the external-

address pins A23 and A22. Also, the memory interface copies the value of the

internal-address A0 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
A24
A23
A22
A21
.
.
.
A3
A2
A1
A0
CS
I/O(7–0)
’C32
A23
A22
A21
A20
A19
.
.
.
A1
A0
STRBx_B3/A-1
STRBx_B2/A-2
STRBx_B0
D(7–0)
A23
A22
A21
A20
.
.
.
A2
A1
A0
Memoryinterface
toggle
’C32’s core address bus
STRBx
logic