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t
d(IDLEXCOL)
X1/X2
or XCLKIN
XCLKOUT
HALT
HALT
Wake-up Latency
Flushing Pipeline
t
d(WAKEHALT)
(A)
(B)
(C)
(D)
Device
Status
(E)
(G)
(F)
PLL Lock-up Time
Normal
Execution
t
w(WAKE-GPIO)
t
p
GPIOn
Oscillator Start-up Time
TMS320F2808, TMS320F2806
TMS320F2801, UCD9501
Digital Signal Processors
SPRS230F–OCTOBER 2003–REVISED SEPTEMBER 2005
Table 6-18. HALT Mode Timing Requirements
MIN
NOM
MAX
UNIT
cycles
cycles
t
w(WAKE-GPIO)
t
w(WAKE-XRS)
(1)
See
Table 6-11
for an explanation of t
oscst
.
Pulse duration, GPIO wake-up signal
Pulse duration, XRS wakeup signal
t
oscst
+ 2t
c(OSCCLK)(1)
t
oscst
+ 8t
c(OSCCLK)
Table 6-19. HALT Mode Switching Characteristics
PARAMETER
MIN
TYP
MAX
UNIT
cycles
cycles
t
d(IDLE-XCOL)
t
p
PLL lock-up time
Delay time, PLL lock to program execution resume
Wake up from flash
–
Flash module in sleep state
32t
c(SCO)
45t
c(SCO)
131072t
c(OSCCLK)
1125t
c(SCO)
cycles
t
d(WAKE-HALT)
35t
c(SCO)
cycles
Wake up from SARAM
A.
B.
IDLE instruction is executed to put the device into HALT mode.
The PLL block responds to the HALT signal. SYSCLKOUT is held for approximately 32 cycles before the oscillator is
turned off and the CLKIN to the core is stopped. This 32-cycle delay enables the CPU pipe and any other pending
operations to flush properly.
Clocks to the peripherals are turned off and the PLL is shut down. If a quartz crystal or ceramic resonator is used as
the clock source, the internal oscillator is shut down as well. The device is now in HALT mode and consumes
absolute minimum power.
When the GPIOn pin is driven low, the oscillator is turned on and the oscillator wake-up sequence is initiated. The
GPIO pin should be driven high only after the oscillator has stabilized. This enables the provision of a clean clock
signal during the PLL lock sequence. Since the falling edge of the GPIO pin asynchronously begins the wakeup
procedure, care should be taken to maintain a low noise environment prior to entering and during HALT mode.
When GPIOn is deactivated, it initiates the PLL lock sequence, which takes 131,072 OSCCLK (X1/X2 or X1 or
XCLKIN) cycles.
When CLKIN to the core is enabled, the device will respond to the interrupt (if enabled), after a latency. The HALT
mode is now exited.
Normal operation resumes.
C.
D.
E.
F.
G.
Figure 6-13. HALT Wake Up Using GPIOn
98
Electrical Specifications