Texas Instruments TMS320C3x User Manual

Page 316

Configuration

10-13

TMS320C32 Enhanced External Memory Interface

Figure 10–7. STRB Configuration

STRB0_Bx

STRB1_Bx

STRB0_Bx

STRB config

STRB1_Bx

10.3.2 Using Physical Memory Width and Data-Type Size Fields

Consider a ’C32 connected to two banks of external memory. In this configura-
tion, one bank is mapped to STRB0 while the other bank is mapped to STRB1.
The STRB0 bank of memory is 32 bits wide and stores 32-bit data types. The
STRB1 bank of memory is 16 bits wide and stores 16-bit data types. You can
transfer these configurations to the ’C32 by setting the physical memory width
and data-type size fields of the respective STRB0 and STRB1 control registers.
You also must clear the STRB config bit field to 0 since the banks are separate
memories. Note that ‘C32 address pins A

...A

are connected to the

STRB0 memory bank address pins A

...A

. But ’C32 address pins

...A

–

are connected to the STRB1 memory-bank address pins

...A

Executing the following code on this device results in the data-access
sequence shown in Table 10–2.

ББ

1)
2)
3)
4)
5)
6)
7)
8)
9)

ББББ

ББ

ББББ

LDI

ADDI

LDI

LSH

LDI

ADDI

БББББ

БББ

БББББ

4000h, AR1

*AR1++, R2

900h, AR2

12, AR2

*AR2++, R3

*AR2, R3

БББББББББББББББ

БББББББББББББ

БББББББББББББББ

; AR1 = 4000h

; R2 = *4000h and AR1 = AR1 + 1

; R2 = R2 + *4001h and AR1 = AR1 + 1

; R2 = R2 + *4002h and AR1 = AR1 + 1

; R2 = R2 + *4003h and AR1 = AR1 + 1

; AR2 = 900h

; AR2 = 900000h

; R3 = *900000h and AR2 = AR2 + 1

; R3 = R3 + 900001h