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UM10850
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User manual
Rev. 2.4 — 13 September 2016
240 of 464
NXP Semiconductors
UM10850
Chapter 17: LPC5410x Multi-Rate Timer (MRT)
17.6.1 Time interval register (INTVAL)
This register contains the MRT load value and controls how the timer is reloaded. The
load value is IVALUE -1.
17.6.2 Timer register (TIMER)
The timer register holds the current timer value. This register is read-only.
Table 281. Time interval register (INTVAL[0:3], address 0x4007 4000 (INTVAL0) to 0x4007 4030 (INTVAL3)) bit
description
Bit
Symbol
Value
Description
Reset
value
23:0
IVALUE
Time interval load value. This value is loaded into the TIMERn register and the MRT
channel n starts counting down from IVALUE -1.
If the timer is idle, writing a non-zero value to this bit field starts the timer immediately.
If the timer is running, writing a zero to this bit field does the following:
•
If LOAD = 1, the timer stops immediately.
•
If LOAD = 0, the timer stops at the end of the time interval.
0
30:24
-
Reserved. Read value is undefined, only zero should be written.
-
31
LOAD
Determines how the timer interval value IVALUE -1 is loaded into the TIMERn register.
This bit is write-only. Reading this bit always returns 0.
0
0
No force load. The load from the INTVALn register to the TIMERn register is processed
at the end of the time interval if the repeat mode is selected.
1
Force load. The INTVALn interval value IVALUE -1 is immediately loaded into the
TIMERn register while TIMERn is running.
Table 282. Timer register (TIMER[0:3], address 0x4007 4004 (TIMER0) to 0x4007 4034 (TIMER3)) bit description
Bit
Symbol
Description
Reset value
23:0
VALUE
Holds the current timer value of the down-counter. The initial value of the TIMERn
register is loaded as IVALUE - 1 from the INTVALn register either at the end of the time
interval or immediately in the following cases:
INTVALn register is updated in the idle state.
INTVALn register is updated with LOAD = 1.
When the timer is in idle state, reading this bit fields returns -1 (0x00FF FFFF).
0x00FF FFFF
31:24
-
Reserved. Read value is undefined, only zero should be written.
0