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UM10601
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2012. All rights reserved.
Preliminary user manual
Rev. 1.0 — 7 November 2012
140 of 313
NXP Semiconductors
UM10601
Chapter 11: LPC800 Multi-Rate Timer (MRT)
11.5.1 Repeat interrupt mode
The repeat interrupt mode generates repeated interrupts after a selected time interval.
This mode can be used for software-based PWM or PPM applications.
When the timer n is in idle state, writing a non-zero value IVALUE to the INTVALn register
immediately loads the time interval value IVALUE - 1, and the timer begins to count down
from this value. When the timer reaches zero, an interrupt is generated, the value in the
INTVALn register IVALUE - 1 is reloaded automatically, and the timer starts to count down
again.
While the timer is running in repeat interrupt mode, you can perform the following actions:
•
Change the interval value on the next timer cycle by writing a new value (>0) to the
INTVALn register and setting the LOAD bit to 0. An interrupt is generated when the
timer reaches zero. On the next cycle, the timer counts down from the new value.
•
Change the interval value on-the-fly immediately by writing a new value (>0) to the
INTVALn register and setting the LOAD bit to 1. The timer immediately starts to count
down from the new timer interval value. An interrupt is generated when the timer
reaches 0.
•
Stop the timer at the end of time interval by writing a 0 to the INTVALn register and
setting the LOAD bit to 0. An interrupt is generated when the timer reaches zero.
•
Stop the timer immediately by writing a 0 to the INTVALn register and setting the
LOAD bit to 1. No interrupt is generated when the INTVALn register is written.
Fig 15. MRT block diagram
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