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UM10601
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© NXP B.V. 2012. All rights reserved.
Preliminary user manual
Rev. 1.0 — 7 November 2012
49 of 313
NXP Semiconductors
UM10601
Chapter 5: LPC800 Reduced power modes and Power Management
5.7.5.2 Programming Deep-sleep mode
The following steps must be performed to enter Deep-sleep mode:
1. The PD bits in the PCON register must be set to 0x1 (
2. Select the power configuration in Deep-sleep mode in the PDSLEEPCFG (
)
register.
3. Select the power configuration after wake-up in the PDAWAKECFG (
register.
4. If any of the available wake-up interrupts are needed for wake-up, enable the
interrupts in the interrupt wake-up registers (
,
) and in the NVIC.
5. Write one to the SLEEPDEEP bit in the ARM Cortex-M0 SCR register.
6. Use the ARM WFI instruction.
5.7.5.3 Wake-up from Deep-sleep mode
The microcontroller can wake up from Deep-sleep mode in the following ways:
•
Signal on one of the eight pin interrupts selected in
. Each pin interrupt must
also be enabled in the STARTERP0 register (
) and in the NVIC.
•
BOD signal, if the BOD is enabled in the PDSLEEPCFG register:
–
BOD interrupt using the deep-sleep interrupt wake-up register 1 (
). The
BOD interrupt must be enabled in the NVIC. The BOD interrupt must be selected in
the BODCTRL register.
–
Reset from the BOD circuit. In this case, the BOD circuit must be enabled in the
PDSLEEPCFG register, and the BOD reset must be enabled in the BODCTRL
register (
).
•
WWDT signal, if the watchdog oscillator is enabled in the PDSLEEPCFG register:
–
WWDT interrupt using the interrupt wake-up register 1 (
). The WWDT
interrupt must be enabled in the NVIC. The WWDT interrupt must be set in the
WWDT MOD register.
–
Reset from the watchdog timer. The WWDT reset must be set in the WWDT MOD
register. In this case, the watchdog oscillator must be running in Deep-sleep mode
(see PDSLEEPCFG register), and the WDT must be enabled in the
SYSAHBCLKCTRL register.
•
Via any of the USART blocks. See
Section 15.3.2 “Configure the USART for
.
•
Via the I2C. See <tbd>.
•
Via any of the SPI blocks. See <tbd>.
Remark:
If the watchdog oscillator is running in Deep-sleep mode, its frequency
determines the wake-up time.
5.7.6 Power-down mode
In Power-down mode, the system clock to the processor is disabled as in Sleep mode. All
analog blocks are powered down, except for the BOD circuit and the watchdog oscillator,
which must be selected or deselected during Power-down mode in the PDSLEEPCFG