ꢀ ꢁꢂ ꢃ ꢄ ꢅ ꢆꢇ ꢈ ꢉꢈ ꢀꢊ ꢀ ꢁꢂ ꢃ ꢄ ꢅ ꢆꢇ ꢈ ꢉꢋ ꢀꢊ ꢀ ꢁꢂ ꢃ ꢄꢅ ꢆꢇ ꢈꢉ ꢇꢀ
ꢌ ꢍꢎ ꢏꢐꢑꢒꢓ ꢍ ꢔꢀ ꢐꢍ ꢕꢍ ꢀꢖꢗ ꢂꢍ ꢕ ꢔꢖꢗ ꢒꢘ ꢓ ꢆꢏ ꢂ ꢂꢓ ꢘ ꢂ
SPRS226H − NOVEMBER 2003 − REVISED AUGUST 2005
31
16
15
14
13
12
11
PD2
R/W-0
10
9
8
0
Enable or
Non-Enabled
Interrupt Wake
Enabled
Interrupt Wake
Reserved
R/W-0
PD3
PD1
R/W-0
R/W-0
R/W-0
R/W-0
7
Legend: R/W−x = Read/write reset value
NOTE: The shadowed bits are not part of the power-down logic discussion and therefore are not covered here. For information on these other
bit fields in the CSR register, see the TMS320C6000 CPU and Instruction Set Reference Guide (literature number SPRU189).
Figure 10. PWRD Field of the CSR Register
A delay of up to nine clock cycles may occur after the instruction that sets the PWRD bits in the CSR before the
PD mode takes effect. As best practice, NOPs should be padded after the PWRD bits are set in the CSR to account
for this delay.
If PD1 mode is terminated by a non-enabled interrupt, the program execution returns to the instruction where
PD1 took effect. If PD1 mode is terminated by an enabled interrupt, the interrupt service routine will be executed
first, then the program execution returns to the instruction where PD1 took effect. In the case with an enabled
interrupt, the GIE bit in the CSR and the NMIE bit in the interrupt enable register (IER) must also be set in order
for the interrupt service routine to execute; otherwise, execution returns to the instruction where PD1 took effect
upon PD1 mode termination by an enabled interrupt.
PD2 and PD3 modes can only be aborted by device reset. Table 32 summarizes all the power-down modes.
Table 32. Characteristics of the Power-Down Modes
PRWD FIELD
(BITS 15−10)
POWER-DOWN
MODE
WAKE-UP METHOD
—
EFFECT ON CHIP’S OPERATION
000000
001001
No power-down
PD1
—
CPU halted (except for the interrupt logic)
Wake by an enabled interrupt
Power-down mode blocks the internal clock inputs at the
boundary of the CPU, preventing most of the CPU’s logic from
switching. During PD1, EDMA transactions can proceed
between peripherals and internal memory.
Wake by an enabled or
non-enabled interrupt
010001
011010
PD1
Output clock from PLL is halted, stopping the internal clock
structure from switching and resulting in the entire chip being
halted. All register and internal RAM contents are preserved. All
functional I/O “freeze” in the last state when the PLL clock is
turned off.
†
PD2
Wake by a device reset
†
When entering PD2 and PD3, all functional I/O remains in the previous state. However, for peripherals which are asynchronous in nature or
peripherals with an external clock source, output signals may transition in response to stimulus on the inputs. Under these conditions,
peripherals will not operate according to specifications.
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