Data Sheet
June 2001
DSP16410B Digital Signal Processor
Agere Systems Inc.
Agere Systems—Proprietary
Use pursuant to Company instructions
123
4 Hardware Architecture
(continued)
4.14 System and External Memory Interface
(SEMI)
(continued)
4.14.6 Synchronous Memory
(continued)
4.14.6.2 Interfacing Examples
For synchronous operation, the programmer
must
con-
figure the SEMI external output clock (ECKO) to CLK/2
by clearing the ECKO field (
ECON1
[1:0]—
Table 60 on
page 110
). The DSP16410B clears the ECKO[1:0]
field by default after reset.
Figures
35
and
36
illustrate examples of interfacing
16-bit and 32-bit pipelined synchronous ZBTSRAMs to
the SEMI. The programmer can individually configure
EROMN, ERAMN, and EION enables to support this
type of synchronous device. The ERTYPE pin must be
at logic high for the EROM component to be configured
for synchronous accesses. Setting the YTYPE field
(
ECON1
[9]) and ITYPE field (
ECON1
[10]) configures
the ERAM and EIO components for synchronous
accesses.
Figure 35 illustrates interfacing the SEMI to a 16-bit
synchronous, pipelined ZBTSRAM. In this example:
1. The SEMI address bus (EA[17:0]) is connected to
the SRAM’s address bus (A[17:0]). One of the SEMI
ESEG[3:0] pins can be optionally connected to the
SRAM’s active-high chip select input (CE2).
2. The upper 16 bits of the SEMI data bus (ED[31:16])
are connected to the SRAM’s bidirectional data bus
(DQ[15:0]).
3. The SEMI external clock (ECKO) is programmed for
operation at f
CLK
/2 and is connected to the SRAM’s
CLK input.
4. The SEMI external data component enable
(ERAMN) and external read/write strobe (ERWN0)
are connected to the SRAM’s active-low chip enable
and write enable inputs, respectively.
5. The SRAM’s active-low
6. The SEMI’s ESIZE pin is tied low to configure the
data bus for 16-bit accesses.
must be tied low.
16-Bit External Interface with 16-Bit ZBT Pipelined Synchronous SRAMs
Figure 35. 16-Bit External Interface with 16-Bit Pipelined, Synchronous ZBTSRAMs
ADV/LD
A[17:0]
CLK
CE1
DQ[15:0]
V
SS
EA[17:0]
ECKO
ERAMN
ED[31:16]
DSP16410B
16-bit SYNCHRONOUS
SRAM
ERWN0
WE
ADV/LD
ESIZE
V
SS
BWa
BWb
V
SS
OE
CE2
ESEG[3:0]
V
DD
ERTYPE