Cautions On 8-Bit Timer/Event Counters 5 And 6; Bit Timer Registers 5 And 6 Start Timing; External Event Counter Operation Timing - NEC PD78081(A) User Manual

6.5 Cautions on 8-Bit Timer/Event Counters 5 and 6

(1) Timer start errors
An error with a maximum of one clock may occur concerning the time required for a match signal to be gener-
ated after timer start. This is because 8-bit timer registers 5 and 6 (TM5 and TM6) are started asynchronously
with the count pulse.
Count Pulse
TM5, TM6 Count Value
(2) 8-bit compare register 50 and 60 setting
The 8-bit compare registers 50 and 60 (CR50 and CR60) can be set to 00H.
Thus, when these 8-bit compare registers are used as event counters, one-pulse count operation can be
carried out.
TI5, TI6, Input
CR50, CR60
TM5, TM6 Count Value
TO5, TO6
Interrupt Request Flag
100
CHAPTER 6 8-BIT TIMER/EVENT COUNTERS 5 AND 6
Figure 6-18. 8-Bit Timer Registers 5 and 6 Start Timing
00H
Timer Start
Figure 6-19. External Event Counter Operation Timing
01H 02H
00H
00H 00H
03H 04H
00H 00H