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UM10360_0
© NXP B.V. 2009. All rights reserved.
User manual
Rev. 00.06 — 5 June 2009
17 of 808
NXP Semiconductors
UM10360
Chapter 3: LPC17xx System control
4.
Reset
Reset has 4 sources on the LPC17xx: the RESET pin, Watchdog Reset, Power On Reset
(POR), and Brown Out Detect (BOD).
The RESET pin is a Schmitt trigger input pin. Assertion of chip Reset by any source, once
the operating voltage attains a usable level, starts the wake-up timer (see description in
in this chapter), causing reset to remain asserted until the
external Reset is de-asserted, the oscillator is running, a fixed number of clocks have
passed, and the flash controller has completed its initialization. The reset logic is shown in
the following block diagram (see
Reset
RSID
Reset Source Identification Register
R/W
0x400F C180
Syscon Miscellaneous Registers
SCS
System Control and Status
R/W
0x00
0x400F C1A0
Table 7.
Summary of system control registers
Name
Description
Access
Reset value
Address
Fig 4.
Reset block diagram including the wake-up timer
C
Q
S
APB read of
PDBIT
in PCON
power-down
C
Q
S
F
OSC
to other
blocks
WAKE-UP TIMER
watchdog
reset
external
reset
START
COUNT 2
n
internal RC
oscillator
Reset to the
on-chip circuitry
Reset to
PCON.PD
write “1”
from APB
reset
EINT0 wake-up
EINT1 wake-up
EINT2 wake-up
POR
BOD
EINT3 wake-up
RTC wake-up
BOD wake-up
Ethernet MAC wake-up
USB need_clk wake-up
CAN wake-up
GPIO0 port wake-up
GPIO2 port wake-up