DSP16411 Datasheet, PDF (149/316 Pages) Agere Systems – DSP16411 Digital Signal Processor

Data Sheet
May 2003
DSP16411 Digital Signal Processor
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 DMAU¹ coordinates and executes host data read commands via its PIU bypass channel (Section 4.13.4 on
page 86). 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 88 describes each host read command in
detail.
Table 88. Memory Read Commands
Command
Mnemonic
load_pdo
This command causes the PIU to:
Description
! Request the DMAU to fetch the single word (16 bits) pointed to by the contents of PA.
! Place the word into PDO.
load_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:
! 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.
unld_pdo
read_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 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 150).
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.
! 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 150).
read_pdo++ This command causes the PIU to:
! 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 150).
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.
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