Cautions Related To 16-Bit Timer/Event Counter 00 - NEC 78K0S/KA1+ Preliminary User's Manual

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6.5

Cautions Related to 16-Bit Timer/Event Counter 00

(1) Timer start errors
An error of up to one clock may occur in the time required for a match signal to be generated after timer start.
This is because 16-bit timer counter 00 (TM00) is started asynchronously to the count clock.
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(2) 16-Bit timer capture/compare register setting
Set 16-bit timer capture/compare register 000 (CR000) to other than 0000H in the clear & start mode entered
on match between TM00 and CR000. This means a 1-pulse count operation cannot be performed when this
register is used as an external event counter.
(3) Capture register data retention
The values of 16-bit timer capture/compare registers 000, 010 (CR000, CR010) after 16-bit timer/event
counter 00 has stopped are not guaranteed.
(4) Valid edge setting
Set the valid edge of the TI000 pin after setting bits 2 and 3 (TMC002 and TMC003) of 16-bit timer mode
control register 00 (TMC00) to 0, 0, respectively, and then stopping the timer operation. The valid edge is set
by bits 4 and 5 (ES000 and ES010) of prescaler mode register 00 (PRM00).
(5) Re-triggering one-shot pulse
(a) One-shot pulse output by software
When a one-shot pulse is output, do not set the OSPT00 bit to 1. Do not output the one-shot pulse again
until INTTM000, which occurs upon a match with the CR000 register, or INTTM010, which occurs upon a
match with the CR010 register, occurs.
(b) One-shot pulse output with external trigger
If the external trigger occurs again while a one-shot pulse is output, it is ignored.
(c) One-shot pulse output function
When using the one-shot pulse output of 16-bit timer/event counter 00 with a software trigger, do not
change the level of the TI000 pin or its alternate function port pin.
Because the external trigger is valid even in this case, the timer is cleared and started even at the level of
the TI000 pin or its alternate function port pin, resulting in the output of a pulse at an undesired timing.
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CHAPTER 6 16-BIT TIMER/EVENT COUNTER 00
Figure 6-36. Start Timing of 16-Bit Timer Counter 00 (TM00)
Count clock
TM00 count value 0000H
Timer start
Preliminary User's Manual U16898EJ1V0UD
0001H 0002H 0003H 0004H