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UM10375
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© NXP B.V. 2011. All rights reserved.
User manual
Rev. 3 — 14 June 2011
275 of 368
NXP Semiconductors
UM10375
Chapter 15: LPC13xx 16-bit timer/counters (CT16B0/1)
15.8.11 Count Control Register (TMR16B0CTCR and TMR16B1CTCR)
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 occurs, and the event corresponds to the one selected by
bits 1:0 in the CTCR register, will the Timer Counter register be incremented.
Effective processing of the externally supplied clock to the counter has some limitations.
Since two successive rising edges of the PCLK clock are used to identify only one edge
on the CAP selected input, the frequency of the CAP input can not exceed one half of the
PCLK clock. Consequently, duration of the HIGH/LOW levels on the same CAP input in
this case can not be shorter than 1/(2
PCLK).
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 (CT16Bn_MATm pin is LOW if
pinned out).
0x2
Set the corresponding External Match bit/output to 1 (CT16Bn_MATm 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 (CT16Bn_MATm pin is LOW if
pinned out).
0x2
Set the corresponding External Match bit/output to 1 (CT16Bn_MATm 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 264. External Match Register (TMR16B0EMR - address 0x4000 C03C and TMR16B1EMR - address
0x4001 003C) bit description
Bit
Symbol
Value
Description
Reset
value
Table 265. 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 (CT16Bn_MATm pin is LOW if
pinned out).
10
Set the corresponding External Match bit/output to 1 (CT16Bn_MATm pin is HIGH if
pinned out).
11
Toggle the corresponding External Match bit/output.