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UM10601
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© NXP B.V. 2012. All rights reserved.
Preliminary user manual
Rev. 1.0 — 7 November 2012
90 of 313
NXP Semiconductors
UM10601
Chapter 8: LPC800 Pin interrupts/pattern match engine
8.6.9 Pin interrupt falling edge register
This register contains ones for pin interrupts selected in the PINTSELn registers (see
) on which a falling edge has been detected. Writing ones to this register
clears falling edge detection. Ones in this register assert an interrupt request for pins that
are enabled for falling-edge interrupts. All edges are detected for all pins selected by the
PINTSELn registers, regardless of whether they are interrupt-enabled.
8.6.10 Pin interrupt status register
Reading this register returns ones for pin interrupts that are currently requesting an
interrupt. For pins identified as edge-sensitive in the Interrupt Select register, writing ones
to this register clears both rising- and falling-edge detection for the pin. For level-sensitive
pins, writing ones inverts the corresponding bit in the Active level register, thus switching
the active level on the pin.
8.6.11 Pattern Match Interrupt Control Register
The pattern match control register contains one bit to select pattern-match interrupt
generation (as opposed to pin interrupts which share the same interrupt request lines),
and another to enable the RXEV output to the cpu. This register also allows the current
state of any pattern matches to be read.
If the pattern match feature is not used (either for interrupt generation or for RXEV
assertion) the two LSB’s of this register should be left at 0b00 to conserve power.
Table 88.
Pin interrupt falling edge register (FALL, address 0xA000 4020) bit description
Bit
Symbol Description
Reset
value
Access
7:0
FDET
Falling edge detect. Bit n detects the falling edge of the pin
selected in PINTSELn.
Read 0: No falling edge has been detected on this pin since
Reset or the last time a one was written to this bit.
Write 0: no operation.
Read 1: a falling edge has been detected since Reset or the
last time a one was written to this bit.
Write 1: clear falling edge detection for this pin.
0
R/W
31:8
-
Reserved.
-
-
Table 89.
Pin interrupt status register (IST, address 0xA000 4024) bit description
Bit
Symbol Description
Reset
value
Access
7:0
PSTAT
Pin interrupt status. Bit n returns the status, clears the edge
interrupt, or inverts the active level of the pin selected in
PINTSELn.
Read 0: interrupt is not being requested for this interrupt pin.
Write 0: no operation.
Read 1: interrupt is being requested for this interrupt pin.
Write 1 (edge-sensitive): clear rising- and falling-edge
detection for this pin.
Write 1 (level-sensitive): switch the active level for this pin (in
the IENF register).
0
R/W
31:8
-
Reserved.
-
-