Data Sheet
June 2001
DSP16410B Digital Signal Processor
Agere Systems Inc.
Agere Systems—Proprietary
Use pursuant to Company instructions
145
4 Hardware Architecture
(continued)
4.15 Parallel Interface Unit (PIU)
(continued)
4.15.5 Host Commands
(continued)
The host issues commands to the PIU through the PIU’s external interface. Host commands allow the host to
access all DSP16410B internal and external memory locations. Host commands can also read or write PIU
scratch and control/status registers. All commands are executed by a combination of actions performed by the PIU
and by the DMAU bypass channel.
A host command consists of four parts:
1. Read versus write operation is determined by the state of the PRWN pin.
2. The selection of a PIU internal register (
PDI
,
PDO
,
PA
,
PCON
,
HSCRATCH
, or
DSCRATCH
) is made by
PADD[3:1].
3. The command can be qualified by the state of the PADD[0] pin. This pin determines if a read or write command
requires a postincrement of the
PA
register.
4. Data is read or driven onto PD[15:0] by the host.
4.15.5.1 Status/Control/Address Register Read Commands
The host can read the
PA
,
PCON
, and
DSCRATCH
registers by issuing the appropriate command as part of a host
read cycle. These commands do
not
affect the state of the
PA
,
PCON
, or
PDO
registers or the state of the PIBF,
POBE, or PRDY pins. No flow control is required for these commands.
Table 84. Status/Control/Address Register Read Commands
4.15.5.2 Status/Control/Address Register Write Commands
The host can write the
PA
,
PCON
, and
HSCRATCH
registers by executing the appropriate command as part of a
host write cycle. Flow control
is
required for these commands, i.e., the host must check the status of the PRDY pin
to ensure that any previous data write has completed before writing to
PA
,
PCON
, or
HSCRATCH
. For a descrip-
tion of flow control, see the flow control description in
Section 4.15.5.5 on page 148
.
Table 85. Status/Control/Address Register Write Commands
Command
Mnemonic
read_pah
read_pal
read_pcon
read_dscratch
This command causes the PIU to place the 16-bit contents of the
DSCRATCH
register onto PD[15:0].
Description
This command causes the PIU to place the upper 16-bit contents of the
PA
register (
PAH
) onto PD[15:0].
This command causes the PIU to place the lower 16-bit contents of the
PA
register (
PAL
) onto PD[15:0].
This command causes the PIU to place the 16-bit contents of the
PCON
register onto PD[15:0].
Command
Mnemonic
write_pah
Description
This command causes the PIU to move the contents of the
PDI
register into the upper 16 bits of the
PA
reg-
ister (
PAH
). The data move begins at the termination of a PIU host write cycle.
This command causes the PIU to move the contents of the
PDI
register into the lower 16 bits of the
PA
reg-
ister (
PAL
). The data move begins at the termination of a PIU host write cycle.
This command causes the PIU to move the contents of the
PDI
register into the
PCON
register. The data
move begins at the termination of a PIU host write cycle.
write_hscratch
This command causes the PIU to move the contents of the
PDI
register into the
HSCRATCH
register. The
data move begins at the termination of a PIU host write cycle.
write_pal
write_pcon