Interrupt Wake-Up Register (Intwake - 0Xe01F C144) - Philips LPC2101 User Manual

Philips Semiconductors
Volume 1
Table 9: External Interrupt Flag register (EXTINT - address 0xE01F C140) bit description
Bit Symbol Description
0 EINT0 In level-sensitive mode, this bit is set if the EINT0 function is selected for its pin, and the pin is in
its active state. In edge-sensitive mode, this bit is set if the EINT0 function is selected for its pin,
and the selected edge occurs on the pin.
This bit is cleared by writing a one to it, except in level sensitive mode when the pin is in its active
state (e.g. if EINT0 is selected to be LOW level sensitive and a LOW level is present on the
corresponding pin, this bit can not be cleared; this bit can be cleared only when the signal on the
pin becomes HIGH).
1 EINT1 In level-sensitive mode, this bit is set if the EINT1 function is selected for its pin, and the pin is in
its active state. In edge-sensitive mode, this bit is set if the EINT1 function is selected for its pin,
and the selected edge occurs on the pin.
This bit is cleared by writing a one to it, except in level sensitive mode when the pin is in its active
state (e.g. if EINT1 is selected to be LOW level sensitive and a LOW level is present on the
corresponding pin, this bit can not be cleared; this bit can be cleared only when the signal on the
pin becomes HIGH).
2 EINT2 In level-sensitive mode, this bit is set if the EINT2 function is selected for its pin, and the pin is in
its active state. In edge-sensitive mode, this bit is set if the EINT2 function is selected for its pin,
and the selected edge occurs on the pin.
This bit is cleared by writing a one to it, except in level sensitive mode when the pin is in its active
state (e.g. if EINT2 is selected to be LOW level sensitive and a LOW level is present on the
corresponding pin, this bit can not be cleared; this bit can be cleared only when the signal on the
pin becomes HIGH).
7:3 - Reserved, user software should not write ones to reserved bits. The value read from a reserved
bit is not defined.

3.5.3 Interrupt Wake-up register (INTWAKE - 0xE01F C144)

Enable bits in the INTWAKE register allow the external interrupts and other sources to
wake up the processor if it is in Power-down mode. The related EINTn function must be
mapped to the pin in order for the wake-up process to take place. It is not necessary for
the interrupt to be enabled in the Vectored Interrupt Controller for a wake-up to take place.
This arrangement allows additional capabilities, such as having an external interrupt input
wake up the processor from Power-down mode without causing an interrupt (simply
resuming operation), or allowing an interrupt to be enabled during Power-down without
waking the processor up if it is asserted (eliminating the need to disable the interrupt if the
wake-up feature is not desirable in the application).
For an external interrupt pin to be a source that would wake up the microcontroller from
Power-down mode, it is also necessary to clear the corresponding bit in the External
Interrupt Flag register (see
Table 10:
Bit
0
1
User manual
Section 3.5.2 on page
Interrupt Wake-up register (INTWAKE - address 0xE01F C144) bit description
Symbol Description
EXTWAKE0 When one, assertion of EINT0 will wake up the processor from
Power-down mode.
EXTWAKE1 When one, assertion of EINT1 will wake up the processor from
Power-down mode.
Rev. 01 — 12 January 2006
UM10161
Chapter 3: System control block
19).
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
Reset
value
0
0
0
NA
Reset
value
0
0
20