Texas Instruments TMS320C3x - Manual (Page 323)

32-Bit-Wide Memory Interface
10-20
10.6 32-Bit-Wide Memory Interface
The ’C32 memory interface to 32-bit-wide external memory uses STRBx_B3
through STRBx_B0 pins as strobe-byte-enable pins as shown in Figure 10–10.
In this manner, the ’C32 can read from, or write to, a single 32-, 16-, or 8-bit value
from the external 32-bit-wide memory.
Figure 10–10. TMS320C32 External Memory Interface for 32-Bit SRAMs
AXX
R/W
STRBx_B3
STRBx_B2
STRBx_B1
STRBx_B0
D(31-24)
D(23-16)
D(15-8)
D(7-0)
AXX
WE
CS
I/O(7- 0)
AXX
WE
CS
I/O(7- 0)
AXX
WE
CS
I/O(7- 0)
AXX
WE
CS
I/O(7- 0)
’C32
Case 1: 32-Bit-Wide Memory With 8-Bit Data-Type Size
When the data-type size is 8 bits, the ’C32 shifts the internal address two bits
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
, A
22
, and A
21
. The memory interface activates the STRBx_B3
through STRBx_B0 pins according to the value of the internal address bits A
1
and A
0
as shown in Table 10–5. Figure 10–11 shows a functional diagram of
the memory interface for 32-bit-wide memory with an 8-bit data-type size.