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UM10316_0
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 00.06 — 17 December 2008
250 of 571
NXP Semiconductors
UM10316
Chapter 17: LPC29xx timer 0/1/2/3
5.1 Timer control register (TCR)
The TCR is used to control the operation of the timer counter. The counting process starts
on CLK_TMRx once the COUNTER_ENABLE bit is set. The process can be reset by
setting the COUNTER_RESET bit. The Timer_Counter and Prescale_Counter remain in
the reset state as long as the COUNTER_RESET bit is active. The counting process is
suspended when the PAUSE_ENABLE bit is set and the pause pin is high.
[1]
Only for MSCSS Timer 0 and MSCSS Timer 1. For all other timers this bit is reserved: do not modify, read
as logic 0.
5.2 Timer counter
The timer counter represents the timer-count value, which is incremented every prescale
cycle. Depending on the prescale register value and the period of CLK_TMRx, this means
that the contents of the register can change very rapidly.
FE8h
W
-
INT_CLR_STATUS
Interrupt clear-status register
see
FECh
W
-
INT_SET_STATUS
Interrupt set-status register
see
FFCh
R
3012 2400h
reserved
Reserved
Table 204. Timer register overview (base address: E004 1000h (timer 0), E004 2000h (timer 1), E004 3000h (timer 2),
E004 4000h (timer 3), E00C 0000h (MSCSS timer 0, E00C1000h (MSCSS timer 1))
…continued
Address
offset
Access
Reset value
Name
Description
Reference
Table 205. TCR register bits
* = reset value
Bit
Variable name
Access
Value
Description
31 to 3
reserved
R
-
Reserved; do not modify, read as logic 0
2
PAUSE_ENABLE
R/W
Enables the pause feature of the timer. If
this bit is set the timer and prescale
counters will be stopped when a logic
HIGH is asserted on timer pin PAUSE
0*
1
COUNTER_RESET
R/W
Reset timer and prescale counter. If this bit
is set the counters remain reset until it is
cleared again
0*
0
COUNTER_ENABLE
R/W
Enable timer and prescale counter. If this
bit is set the counters are running
0*
Table 206. TC register bits
* = reset value
Bit
Variable name
Access
Value
Description
31 to 0
TC[31:0]
R/W
Timer counter. It is advisable not to access this
register, which may change very rapidly
0000 00
00h*