
Data Sheet
June 2001
DSP16410B Digital Signal Processor
146
Agere Systems—Proprietary
Use pursuant to Company instructions
Agere Systems Inc.
4 Hardware Architecture
(continued)
4.15 Parallel Interface Unit (PIU)
(continued)
4.15.5 Host Commands
(continued)
4.15.5.3 Memory Read Commands
The DMAU
1
coordinates and executes host data read commands via its PIU bypass channel (
Section 4.13.4 on
page 85
). Prior to issuing a data read command, the host must initialize the
PA
register with the starting address in
memory by executing the
write_pah
and
write_pal
commands.
Table 86
describes each host read command in
detail:
Table 86. Memory Read Commands
1. A core can coordinate host data read commands by program control, but this is very inefficient compared to using the DMAU for this pur-
pose.
Command
Mnemonic
load_pdo
Description
This command causes the PIU to:
Request the DMAU to fetch the single word (16 bits) pointed to by the contents of
PA
.
Place the word into
PDO
.
The host does not wait for the data after issuing this command (flow control can be ignored), but must issue
a subsequent
unld_pdo
command.
This command causes the PIU to:
load_pdo++
Request the DMAU to fetch the single word (16 bits) pointed to by the contents of
PA
.
Place the word into
PDO
.
Postincrement the address in
PA
by one to point to the next single-word location.
The host does not wait for the data after issuing this command (flow control can be ignored), but must issue
a subsequent
unld_pdo
command.
This command causes the PIU to drive the current contents of
PDO
onto PD[15:0]. The host must use
proper flow control with this command (see
Section 4.15.5.4 on page 147
).
This command causes the PIU to:
unld_pdo
read_pdo
Request the DMAU to fetch the single word (16 bits) pointed to by the contents of
PA
.
Place the word into
PDO
.
Drive the contents of
PDO
onto PD[15:0].
The host must use proper flow control with this command (see
Section 4.15.5.4 on page 147
).
This command causes the PIU to:
read_pdo++
Request the DMAU to fetch the single word (16 bits) from the address in
PA
.
Place the word into
PDO
.
Drive the contents of
PDO
onto PD[15:0].
Postincrement the address in
PA
by one to point to the next single-word location.
The host must use proper flow control with this command (see
Section 4.15.5.4 on page 147
).