ADSP-2192 Peripheral Device Control Registers
B-20 ADSP-219x/2192 DSP Hardware Reference
Table B-6. DSP Interrupt/Powerdown (PWRPx) Register Bit Descriptions
Bit Position
Bit Name
Description
0
PD
DSP PowerDown.
When written to a 1, causes the DSP to power down (enter its
power-down handler). Can also be used to abort a power-up:
if the DSP is in the power-down handler after executing an
IDLE, writing a 1 will cause the DSP to immediately re-enter
the PowerDown interrupt handler after it executes the RTI.
When read,
PD
=1 indicates that this DSP is powered down:
either (a) it is in the powerdown handler and has executed an
IDLE instruction), and/or (b) the DSP Clock Generator
(PLL) is not running and stable. When both DSPs are pow-
ered down, the DSP Clock Generator is powered down, and
automatically restarts when either DSP wakes up.
Note: DSP memory cannot be accessed via PCI or USB when
the DSP is powered down. There is a delay after powering up
the DSPs with the
PU
bit during which memory reads must
not be performed, because the XTAL or the DSP PLL is not
yet running and stable. After powering up by writing a 1 to
the
PU
bit, the
PD
bit must be polled until it becomes 0, after
which the clock generator will be running and it is safe to
access DSP memory again.
1
PU
DSP PowerUp.
When written to a 1, causes the DSP to power up (exit the
IDLE within its power-down handler). Can also be used to
abort a powerdown: when written to 1 while the DSP is
within its powerdown handler prior to the IDLE, writing a 1
will cause execution to immediately continue through the
IDLE without stopping clocks.
When read,
PU
=1 indicates that this DSP is in the powerdown
interrupt handler, whether or not it has executed the power-
down IDLE.
