16-Bit-Wide Memory Interface
10-30
Case 6: 16-Bit-Wide Memory with 32-Bit Data-Type Size

When the data type size is 32 bits, the ’C32 does not shift the internal address

before presenting it to the external address pins. In this case, the memory

interface copies the value of the internal address bus to the respective external

address pins. The memory interface also toggles STRBx_B3/A–1 twice to

perform two 16-bit memory accesses. In the consecutive memory accesses,

the memory interface activates STRBx_B1 and STRBx_B0. In summary, the

memory interface seems to add one wait state to the 32-bit data access.

Figure 10–17 depicts a functional diagram of the memory interface for 16-bit

wide memory with 32-bit data type size.

Figure 10–17. Functional Diagram for 32-Bit Data-Type Size and 16-Bit External-Memory
Width
STRBx_B3/A–1
STRBx_B1
STRBx_B0
A24
A23
A22
A21
.
.
.
A3
A2
A1
A0
CS
I/O(7-0)
A24
A23
A22
A21
.
.
.
A3
A2
A1
A0
CS
I/O(7-0)
’C32
A23
A22
A21
A20
.
.
.
A2
A1
A0
D(15-8)
D(7-0)
A23
A22
A21
A20
.
.
.
A2
A1
A0
Memoryinterface
STRBxlogic
’C32’s core address bus
toggle
For example, reading or writing to memory locations 4000h to 4004h involves

the pins listed in Table 10–13.