UM10503
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User manual
Rev. 1.3 — 6 July 2012
860 of 1269
NXP Semiconductors
UM10503
Chapter 29: LPC43xx Timer0/1/2/3
29.6.11 Timer count control registers
The Count Control Register (CTCR) is used to select between Timer and Counter mode,
and in Counter mode to select the pin and edge(s) for counting.
When Counter Mode is chosen as a mode of operation, the CAP input (selected by the
CTCR bits 3:2) is sampled on every rising edge of the PCLK clock. After comparing two
consecutive samples of this CAP input, one of the following four events is recognized:
rising edge, falling edge, either of edges or no changes in the level of the selected CAP
input. Only if the identified event corresponds to the one selected by bits 1:0 in the CTCR
register, the Timer Counter register will be incremented.
9:8
EMC2
External Match Control 2. Determines the functionality of
External Match 2.
00
0x0
Do Nothing.
0x1
Clear the corresponding External Match bit/output to 0
(MATn.m pin is LOW if pinned out).
0x2
Set the corresponding External Match bit/output to 1 (MATn.m
pin is HIGH if pinned out).
0x3
Toggle the corresponding External Match bit/output.
11:10 EMC3
External Match Control 3. Determines the functionality of
External Match 3.
00
0x0
Do Nothing.
0x1
Clear the corresponding External Match bit/output to 0
(MATn.m pin is LOW if pinned out).
0x2
Set the corresponding External Match bit/output to 1 (MATn.m
pin is HIGH if pinned out).
0x3
Toggle the corresponding External Match bit/output.
31:12 -
Reserved, user software should not write ones to reserved bits.
The value read from a reserved bit is not defined.
NA
Table 694. External Match Control
EMR[11:10], EMR[9:8],
EMR[7:6], or EMR[5:4]
Function
00
Do Nothing.
01
Clear the corresponding External Match bit/output to 0 (MATn.m pin is
LOW if pinned out).
10
Set the corresponding External Match bit/output to 1 (MATn.m pin is
HIGH if pinned out).
11
Toggle the corresponding External Match bit/output.
Table 693. Timer external match registers (EMR - addresses 0x4008 403C (TIMER0),
0x4008 503C (TIMER1), 0x400C 303C (TIMER2), 0x400C 403C (TIMER3)) bit
description
Bit
Symbol Value
Description
Reset
value