TMS320F28027_17 Datasheet, PDF (122/138 Pages) Texas Instruments – Piccolo Microcontrollers

TMS320F28027, TMS320F28026, TMS320F28023, TMS320F28022
TMS320F28021, TMS320F28020, TMS320F280200
SPRS523K – NOVEMBER 2008 – REVISED JUNE 2016
www.ti.com
Device
Status
GPIOn^(I)
(A)
(B)
Flushing Pipeline
X1/X2 or
XCLKIN
XCLKOUT
(C)
(F)
(D)(E)
HALT
HALT
PLL Lock-up Time
Wake-up Latency
(H)
(G)
Normal
Execution
t_w(WAKE-GPIO)
t_{d(WAKE−HALT )}
t_p
Oscillator Start-up Time
t_{d(IDLE−XCOL)}
A. IDLE instruction is executed to put the device into HALT mode.
B. The PLL block responds to the HALT signal. SYSCLKOUT is held for the number of cycles indicated below before
oscillator is turned off and the CLKIN to the core is stopped:
• 16 cycles, when DIVSEL = 00 or 01
• 32 cycles, when DIVSEL = 10
• 64 cycles, when DIVSEL = 11
This delay enables the CPU pipeline and any other pending operations to flush properly.
C. 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. It is possible to keep the zero-pin internal oscillators (INTOSC1 and INTOSC2) and the
watchdog alive in HALT mode. This is done by writing to the appropriate bits in the CLKCTL register.
D. When the GPIOn pin (used to bring the device out of HALT) 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.
E. The wake-up signal fed to a GPIO pin to wake up the device must meet the minimum pulse width requirement.
Furthermore, this signal must be free of glitches. If a noisy signal is fed to a GPIO pin, the wake-up behavior of the
device will not be deterministic and the device may not exit low-power mode for subsequent wake-up pulses.
F. Once the oscillator has stabilized, the PLL lock sequence is initiated, which takes 1 ms.
G. 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.
H. Normal operation resumes.
I. From the time the IDLE instruction is executed to place the device into low-power mode (LPM), wakeup should not be
initiated until at least 4 OSCCLK cycles have elapsed.
Figure 6-47. HALT Wake-Up Using GPIOn
122 Detailed Description
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TMS320F28020 TMS320F280200