NXP Semiconductors LPC24XX UM10237 - Manual (Page 27)

UM10237_4 © NXP B.V. 2009. All rights reserved.
User manual Rev. 04 — 26 August 2009 27 of 792
1. Summary of system control block functions
The System Control Block includes several system features and control registers for a
number of functions that are not related to specific peripheral devices. These include:
• Reset
• Brown-Out Detection
• External Interrupt Inputs
• Miscellaneous System Controls and Status
• Code Security vs. Debugging
Each type of function has its own register(s) if any are required and unneeded bits are
defined as reserved in order to allow future expansion. Unrelated functions never share
the same register addresses
2. Pin description
Table 3–22 shows pins that are associated with system control block functions.
3. Register description
All registers, regardless of size, are on word address boundaries. Details of the registers
appear in the description of each function.
UM10237
Chapter 3: LPC24XX System control
Rev. 04 — 26 August 2009 User manual
Table 22. Pin summary
Pin name Pin
direction Pin description
EINT0 Input External Interrupt Input 0 - An active low/high level or
falling/rising edge general purpose interrupt input. This pin may be
used to wake up the processor from Idle or Power-down modes.
EINT1 Input External Interrupt Input 1 - See the EINT0 description above.
EINT2 Input External Interrupt Input 2 - See the EINT0 description above.
EINT3 Input External Interrupt Input 3 - See the EINT0 description above.
RESET Input External Reset input - A LOW on this pin resets the chip, causing
I/O ports and peripherals to take on their default states, and the
processor to begin execution at address 0x0000 0000.
Table 23. Summary of system control registers
Name Description Access Reset value [1] Address
External interrupts
EXTINT External Interrupt Flag Register R/W 0x00 0xE01F C140
EXTMODE External Interrupt Mode register R/W 0x00 0xE01F C148
EXTPOLAR External Interrupt Polarity Register R/W 0x00 0xE01F C14C