Datasheet
TMS320F28027, TMS320F28026, TMS320F28023, TMS320F28022
TMS320F28021, TMS320F28020, TMS320F280200
www.ti.com
SPRS523J –NOVEMBER 2008–REVISED OCTOBER 2013
3.8 Low-power Modes Block
Table 3-20 summarizes the various modes.
Table 3-20. Low-power Modes
MODE LPMCR0(1:0) OSCCLK CLKIN SYSCLKOUT EXIT
(1)
XRS, CPU-watchdog interrupt, any
IDLE 00 On On On
enabled interrupt
On XRS, CPU-watchdog interrupt, GPIO
STANDBY 01 Off Off
(CPU-watchdog still running) Port A signal, debugger
(2)
Off
(on-chip crystal oscillator and
XRS, GPIO Port A signal, debugger
(2)
,
HALT
(3)
1X PLL turned off, zero-pin oscillator Off Off
CPU-watchdog
and CPU-watchdog state
dependent on user code.)
(1) The Exit column lists which signals or under what conditions the low power mode is exited. A low signal, on any of the signals, exits the
low power condition. This signal must be kept low long enough for an interrupt to be recognized by the device. Otherwise, the low-power
mode will not be exited and the device will go back into the indicated low power mode.
(2) The JTAG port can still function even if the CPU clock (CLKIN) is turned off.
(3) The WDCLK must be active for the device to go into HALT mode.
The various low-power modes operate as follows:
IDLE Mode: This mode is exited by any enabled interrupt that is recognized by the
processor. The LPM block performs no tasks during this mode as long as
the LPMCR0(LPM) bits are set to 0,0.
STANDBY Mode: Any GPIO port A signal (GPIO[31:0]) can wake the device from STANDBY
mode. The user must select which signal(s) will wake the device in the
GPIOLPMSEL register. The selected signal(s) are also qualified by the
OSCCLK before waking the device. The number of OSCCLKs is specified in
the LPMCR0 register.
HALT Mode: CPU-watchdog, XRS, and any GPIO port A signal (GPIO[31:0]) can wake
the device from HALT mode. The user selects the signal in the
GPIOLPMSEL register.
NOTE
The low-power modes do not affect the state of the output pins (PWM pins included). They
will be in whatever state the code left them in when the IDLE instruction was executed. See
the TMS320x2802x/TMS320F2802xx Piccolo System Control and Interrupts Reference
Guide (literature number SPRUFN3) for more details.
Copyright © 2008–2013, Texas Instruments Incorporated Functional Overview 47
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