OM13008,598 NXP Semiconductors, OM13008,598 Datasheet - Page 51

• Manufacturer Part Number: OM13008,598
• Description: BOARD LPC XPRESSO LPC122X
• Manufacturer: NXP Semiconductors
• Series: LPCXpressor

Specifications of OM13008,598

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 568-6642; OM13008

NXP Semiconductors
4.9 Deep power-down mode details
UM10441
User manual
4.8.3 Using the RTC to wake up from Deep-sleep mode (start logic 1)
4.9.1 Using the WAKEUP pin to wake up from Deep power-down mode
4.9.2 Using the RTC to wake up from Deep power-down mode
The RTC is clocked by the independent RTC oscillator and continues to run in Deep-sleep
mode. The RTC interrupt is internally connected to bit 18 in the start logic 1 block and can
serve as wake-up interrupt. The user must program the start logic 1 registers for the RTC
interrupt to enable the RTC wake-up and select the rising edge configuration.
Furthermore, the RTC interrupt must be enabled in the NVIC.
Pulling the WAKEUP pin LOW wakes up the LPC122x from Deep power-down, and the
microcontroller goes through the entire reset process
width for the HIGH-to-LOW transition on the WAKEUP pin is 50 ns.
Follow these steps to wake up the microcontroller from Deep power-down mode using the
WAKEUP pin:
An RTC interrupt wakes up the microcontroller from Deep power-down mode in the same
way the WAKEUP pin does. The wake-up signal is generated when an RTC interrupt is
created after a programmed number of clocks.
To use the RTC wake-up interrupt, the RTC must be configured as follows:
Follow these steps to wake up from Deep power-down mode using the RTC:
1. Generate a wake-up signal by going HIGH-to-LOW externally on the WAKEUP pin
2. Once the microcontroller has booted, read the deep power-down flag in the PCON
3. Clear the deep power-down flag in the PCON register
4. (Optional) Read the stored data in the general purpose registers
5. Set up the PMU for the next Deep power-down cycle.
1. Generate a self-timed RTC wake-up interrupt by setting the RTC match register.
•
•
•
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
– All registers except the GPREG0 to GPREG3 will be in their reset state.
– The contents of the RTC registers will be preserved if the RTC is enabled.
register
power-down.
Table
Program the RTC match register with the RTC timer match value
Clear the interrupt mask in the RTC interrupt mask register
The clock source for the RTC must be the RTC oscillator
the power-on-reset (POR) trip point, a system reset will be triggered and the
microcontroller re-boots.
58).
(Table
All information provided in this document is subject to legal disclaimers.
57) to verify that the reset was caused by a wake-up event from Deep
Rev. 1.1 — 10 March 2011
Chapter 4: LPC122x System control (SYSCON)
(Section
(Table
(Table
4.6). The minimum pulse
(Table
55).
58).
(Table 57
(Table
UM10441
259).
© NXP B.V. 2011. All rights reserved.
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