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UM10375
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© NXP B.V. 2011. All rights reserved.
User manual
Rev. 3 — 14 June 2011
46 of 368
NXP Semiconductors
UM10375
Chapter 3: LPC13xx System configuration
3.9.4.2 Programming Deep power-down mode
The following steps must be performed to enter Deep power-down mode:
1. Write one to the DPDEN bit in the PCON register (see
2. Store data to be retained in the general purpose registers (
).
3. Write one to the SLEEPDEEP bit in the ARM Cortex-M3 SCR register.
4. For the LPC1311/13/42/43, ensure that the IRC is powered by setting bits
IRCOUT_PD and IRC_PD to zero in the PDRUNCFG register before entering Deep
power-down mode. This step is not required for the LPC1311/01 and LPC1313/01.
5. Use the ARM WFI instruction.
Remark:
The WAKEUP pin must be pulled HIGH externally before entering Deep
power-down mode.
3.9.4.3 Wake-up from Deep power-down mode
Pulling the WAKEUP pin LOW wakes up the LPC13xx from Deep power-down, and the
chip goes through the entire reset process (
). The minimum pulse width for the
HIGH-to-LOW transition on the WAKEUP pin is 50 ns.
1. A wake-up signal is generated when a HIGH-to-LOW transition occurs externally on
the WAKEUP pin with a pulse length of at least 50 ns while the part is in Deep
power-down mode.
–
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.
–
All registers except the GPREG0 to GPREG4 will be in their reset state.
2. Once the chip has booted, read the deep power-down flag in the PCON register
(
) to verify that the reset was caused by a wake-up event from Deep
power-down.
3. Clear the deep power-down flag in the PCON register (
4. (Optional) Read the stored data in the general purpose registers (
and
).
5. Set up the PMU for the next Deep power-down cycle.
Remark:
The RESET pin has no functionality in Deep power-down mode.
3.10 Deep-sleep mode details
3.10.1 IRC oscillator
The IRC is the only oscillator on the LPC13xx that can always shut down glitch-free.
Therefore it is recommended that the user switches the clock source to IRC before the
chip enters Deep-sleep mode.