UM11029
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© NXP Semiconductors N.V. 2017. All rights reserved.
User manual
Rev. 1.0 — 16 June 2017
250 of 515
NXP Semiconductors
UM11029
Chapter 15: LPC84x Reduced power modes and power management
15.6.2 General purpose registers 0 to 3
The general purpose registers retain data through the deep power-down mode when
power is still applied to the V
DD
pin but the chip has entered deep power-down mode.
Only a cold boot - when all power has been completely removed from the chip - will reset
the general purpose registers.
15.6.3 Deep power-down control register
The deep power-down control register controls the low-power oscillator that can be used
by the self-wake-up timer to wake up from Deep power-down mode. In addition, this2
register configures the functionality of the WAKEUP pin (PIO0_4) and the RESET pin
(PIO0_5).
The bits in the register not used for deep power-down control (bits 31:4) can be used for
storing additional data which are retained in deep power-down mode in the same way as
registers GPREG0 to GPREG3.
Remark:
If there is a possibility that the external voltage applied on pin V
DD
drops below
2.2 V during deep power-down, the hysteresis of the WAKEUP or the RESET input pin
has to be disabled in this register before entering deep power-down mode in order for the
chip to wake up.
Remark:
Enabling the low-power oscillator in deep power-down mode increases the
power consumption. Only enable this oscillator if you need the self-wake-up timer to wake
up the part from deep power-down mode. You may need the self-wake-up timer if the
wake-up pin is used for other purposes and the wake-up function is not available.
11
DPDFLAG
Deep power-down flag
0
0
Not deep power-down. Read: deep power-down mode
not
entered.
Write: No effect.
0
1
Deep power-down. Read: deep power-down mode
entered.
Write: Clear the deep power-down flag.
31:12 -
-
Reserved. Do not write ones to this bit.
0
Table 291. Power control register (PCON, address 0x4002 0000) bit description
…continued
Bit
Symbol
Value
Description
Reset
value
Table 292. General purpose registers 0 to 3 (GPREG[0:3], address 0x4002 0004 (GPREG0) to
0x4002 0010 (GPREG3)) bit description
Bit
Symbol
Description
Reset
value
31:0
GPDATA
Data retained during deep power-down mode.
0x0
Table 293. Deep power down control register (DPDCTRL, address 0x4002 0014) bit description
Bit
Symbol
Value
Description
Reset
value
0
WAKEUPHYS
WAKEUP pin hysteresis enable
0
0
Disabled. Hysteresis for WAKEUP pin disabled.
1
Enabled. Hysteresis for WAKEUP pin enabled.