Computer Hardware User's Guide

8-Bit-Wide Memory Interface
10-35 TMS320C32 Enhanced External Memory Interface
For example, reading or writing to memory locations A04000h to A04002h
involves the pins listed in Table 10–15.
Table 10–15. Example of 8-Bit-Wide Memory With 16-Bit Data-Type Size
Internal
Address Bus
External
Address Pins
STRB0_B3/A
–1
STRB0_B3/A
–2
Active Strobe
Byte Enable
Accessed
Data Pins
A04000h D02000h
D02000h
0
0
0
1
STRB1_B0
STRB1_B0
D
7–0
D
7–0
A04001h D02001h
D02001h
1
1
0
1
STRB1_B0
STRB1_B0
D
7–0
D
7–0
A04002h D02002h
D02002h
0
0
0
1
STRB1_B0
STRB1_B0
D
7–0
D
7–0
Case 9: 8-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
and
STRBx_B2/A
–2
to perform four 8-bit memory accesses. In the consecutive
memory accesses, the memory interface activates STRBx_B0. In summary,
the memory interface adds three wait states to the 32-bit data access.
Figure 10–21 shows a functional diagram of the memory interface for 8-bit-
wide memory with 32-bit data-type size.