Data Sheet
June 2001
DSP16410B Digital Signal Processor
Agere Systems Inc.
Agere Systems—Proprietary
Use pursuant to Company instructions
107
4 Hardware Architecture
(continued)
4.14 System and External Memory Interface (SEMI)
(continued)
4.14.2 16-Bit External Bus Accesses
Regardless of the configuration of the external data bus via the ESIZE pin, each access by a core or the DMAU can
be a 16-bit (single-word) or 32-bit (double-word) access.
Table 56
summarizes each type of access for a 16-bit
external bus configuration (ESIZE = 0).
Table 56. 16-Bit External Bus Configuration
4.14.3 32-Bit External Bus Accesses
Regardless of the configuration of the external data bus via the ESIZE pin, each access by a core or the DMAU can
be a 16-bit (single-word) or 32-bit (double-word) access.
Table 57
summarizes each type of access for a 32-bit
external bus configuration (ESIZE = 1).
Table 57. 32-Bit External Bus Configuration
Internal Address
Even or Odd
Type of Access
Single-Word Read
Single-Word Write
Double-Word Read
External Address
Even or Odd
External Data
ED[31:16]
ED[31:16]
ED[31:16]
ED[31:16]
ED[31:16]
ED[31:16]
ED[31:16]
ED[31:16]
ED[31:16]
ED[31:16]
ERWN1
1
1
1
1
1
1
1
1
1
1
ERWN0
1
0
1
1
0
0
1
1
0
0
EA[18:0]
EA[18:0]
EA[18:0]
EA[18:0]
EA[18:0]
EA[18:0]
EA[18:0]
EA[18:0]
EA[18:0]
EA[18:0]
Even (aligned
)
The SEMI performs two separate back-to-back 16-bit accesses, even address (most significant data) first and odd address (least significant data) sec-
ond.
The SEMI performs two separate 16-bit accesses, odd address (most significant data) first and even address (least significant data) second. The two
accesses are not necessarily back-to-back, i.e., they can be separated by other accesses.
Even
Odd
Even
Odd
Odd
Even
Odd
Even
Double-Word Write
Odd (misaligned
)
Double-Word Read
Double-Word Write
Internal Address
Even
Type of Access
Single-Word Read
Single-Word Write
Single-Word Read
Single-Word Write
Double-Word Read
Double-Word Write
Double-Word Read
External Address
EA[18:1]
EA[18:1]
EA[18:1]
EA[18:1]
EA[18:1]
EA[18:1]
EA[18:1]
EA[18:1]
EA[18:1]
EA[18:1]
External Data
ED[31:16]
ED[31:16]
ED[15:0]
ED[15:0]
ED[31:0]
ED[31:0]
ED[15:0]
ED[31:16]
ED[15:0]
ED[31:16]
ERWN1
1
1
1
0
1
0
1
1
0
1
ERWN0
1
0
1
1
1
0
1
1
1
0
For a write operation to a synchronous memory component, the SEMI also drives the EA0 pin low for use as a write enable. The EROM component is
synchronous if the ERTYPE pin is logic 1. The ERAM component is synchronous if the YTYPE field (
ECON1
[9]) is set. The EIO component is synchro-
nous if the ITYPE field (
ECON1
[10]) is set.
ECON1
is described in
Table 60 on page 110
.
The SEMI performs two separate 16-bit accesses. It accesses the most significant data in the odd address first, and then the least significant data in
the even address second. The two accesses are not necessarily back-to-back, i.e., they can be separated by other accesses.
Odd
Even (aligned)
Odd (misaligned
)
Double-Word Write