
Data Sheet
June 2001
DSP16410B Digital Signal Processor
Agere Systems Inc.
Agere Systems—Proprietary
Use pursuant to Company instructions
119
4 Hardware Architecture
(continued)
4.14 System and External Memory Interface (SEMI)
(continued)
4.14.5 Asynchronous Memory
(continued)
4.14.5.3 Interfacing Examples
Figures
32
and
33
illustrate two examples of interfacing 16-bit asynchronous SRAMs to the SEMI. The user can
individually configure the EROMN, ERAMN, and EION enables to support asynchronous devices. The ERTYPE
pin must be at logic low for the EROM component to be configured for asynchronous accesses. Clearing the
YTYPE field (
ECON1
[9]) and ITYPE field (
ECON1
[10]) configures the ERAM and EIO components for asynchro-
nous accesses.
The programmer can individually configure the access time (defined as the number of CLK cycles that the enable is
asserted) for each enable. The YATIME field (
ECON0
[7:4]) specifies the number of CLK cycles that the ERAMN
enable is asserted. The XATIME field (
ECON0
[3:0]) specifies the number of CLK cycles that the EROMN enable is
asserted. The IATIME field (
ECON0
[11:8]) specifies the number of CLK cycles that the EION enable is asserted.
The range of values for these fields is from 0 to 15 (corresponding to a range of 1 to 15 CLK cycles). A value of 0
or 1 programs a 1 CLK assertion time for the corresponding enable.