
UM10800
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© NXP Semiconductors N.V. 2016. All rights reserved.
User manual
Rev. 1.2 — 5 October 2016
73 of 487
NXP Semiconductors
UM10800
Chapter 6: LPC82x Reduced power modes and power management
–
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.
–
Via any of the USART blocks. See
Section 13.3.2 “Configure the USART for
–
Via the I2C. See
.
–
Via any of the SPI blocks. See
6.7.7 Deep power-down mode
In Deep power-down mode, power and clocks are shut off to the entire chip with the
exception of the WAKEUP pin and the self-wake-up timer.
During Deep power-down mode, the contents of the SRAM and registers are not retained
except for a small amount of data which can be stored in the general purpose registers of
the PMU block.
All functional pins are tri-stated in Deep power-down mode except for the WAKEUP pin. In
this mode, you must pull the RESET pin HIGH externally.
Remark:
Setting bit 3 in the PCON register (
) prevents the part from entering
Deep-power down mode.
6.7.7.1 Power configuration in Deep power-down mode
Deep power-down mode has no configuration options. All clocks, the core, and all
peripherals are powered down. Only the WAKEUP pin and the self-wake-up timer are
powered.
6.7.7.2 Programming Deep power-down mode using the WAKEUP pin:
The following steps must be performed to enter Deep power-down mode when using the
WAKEUP pin for waking up:
1. Pull the WAKEUP pin externally HIGH.
2. Ensure that bit 3 in the PCON register (
) is cleared.
3. Write 0x3 to the PM bits in the PCON register (see
).
4. Store data to be retained in the general purpose registers (
).
5. Write one to the SLEEPDEEP bit in the ARM Cortex-M0+ SCR register (
6. Use the ARM WFI instruction.
6.7.7.3 Wake-up from Deep power-down mode using the WAKEUP pin:
Pulling the WAKEUP pin LOW wakes up the LPC800 from Deep power-down, and the
part goes through the entire reset process.
1. On the WAKEUP pin, transition from HIGH to LOW.
–
The PMU will turn on the on-chip voltage regulator. When the core voltage reaches
the power-on-reset (POR) trip point, a system reset will be triggered and the chip
re-boots.