Data Sheet
June 2001
DSP16410B Digital Signal Processor
Agere Systems Inc.
Agere Systems—Proprietary
Use pursuant to Company instructions
139
4 Hardware Architecture
(continued)
4.15 Parallel Interface Unit (PIU)
(continued)
4.15.2 Hardware Interface
(continued)
4.15.2.3 Flags, Interrupt, and Ready Pins
The PIU provides buffer status flag pins, an interrupt to the host, and a host ready and mode pin pair.
Table 82. Flags, Interrupt, and Ready Pins
Pin
Name
POBE
(output)
Buffer Empty
PIBF
(output)
Buffer Full
Value
0
1
0
1
Description
PIU Output
PDO
contains data ready for the host to read.
PDO
is empty, i.e., there is no data for the host to read.
PDI
is empty, so the host can safely write another word into
PDI
.
PDI
is full with the previous word that was written by the host. If the host
writes
PDI
, the previous data is overwritten.
A core has not requested an interrupt to the host.
A core has requested an interrupt to the host by setting the PINT field
(
PCON
[3]—
Table 73 on page 133
). The host acknowledges the interrupt
by writing a 1 to the PINT field, clearing it.
PRDY is active-low.
PRDY is active-high.
For a host data read operation, the read data in
PDO
and on PD[15:0] is
valid and the host can latch the data and conclude the read cycle
.
PIU Input
PINT
(output)
PIU Interrupt
Host
0
1
PRDYMD
(input)
PRDY
§
(output)
PIU Ready
Mode
PIU Ready
0
1
If
PRDYMD = 0
0
For a host write operation, the previous write operation has been pro-
cessed by the DSP16410B (
PDI
is empty) and the host can conclude
the current write cycle
, i.e., can write
PDI
with new data.
For a host data read operation, the DSP16410B is processing the cur-
rent read operation (
PDO
is still empty) and the host must extend the
current access until the PIU drives PRDY low before concluding the read
cycle
.
1
For a host write operation, the DSP16410B is processing the previous
write operation (
PDI
is still full) and the host must extend the current
access until the PIU drives PRDY low before concluding the write
cycle
.
For a host data read operation, the DSP16410B is processing the cur-
rent read operation (
PDO
is still empty) and the host must extend the
current access until the PIU drives PRDY high before concluding the
read cycle
.
If
PRDYMD = 1
0
For a host write operation, the DSP16410B is processing the previous
write operation (
PDI
is still full) and the host must extend the current
access until the PIU drives PRDY high before concluding the write
cycle
.
For a host data read operation, the read data in
PDO
and on PD[15:0] is
valid and the host can latch the data and conclude the read cycle
.
1
For a host write operation, the previous write operation has been pro-
cessed by the DSP16410B (
PDI
is empty) and the host can conclude
the current write cycle
, i.e., can write
PDI
with new data.
§
The state of this pin is also readable by the cores in the POBE field (
PCON
[0]—see
Table 73 on page 133
).
The state of this pin is also readable by the cores in the PIBF field (
PCON
[1]—see
Table 73 on page 133
).
For the descriptions in this table to be valid, the PIU must be activated, i.e., PSTRN must be asserted. See
Section 4.15.2.1 on page 137
for a defini-
tion of PSTRN.
See description of PIDS and PODS in
Table 80 on page 137
.