CHAPTER 7 8-BIT TIMER/EVENT COUNTERS 50 AND 51
Preliminary User’s Manual U16315EJ1V0UD
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(2) Operation with CR5n changed
Figure 7-13. Timing of Operation with CR5n Changed
(a) CR5n value is changed from N to M before clock rising edge of FFH
→
→
→
→
Value is reloaded to CR5n at overflow immediately after change.
Count clock
TM5n
CR5n
TCE5n
INTTM5n
TO5n
<1> CR5n change (N
→
M)
N N + 1 N + 2
FFH 00H 01H
M M + 1 M + 2
FFH 00H 01H 02H
M M + 1 M + 2
N
02H
M
H
<2>
(b) CR5n value is changed from N to M after clock rising edge of FFH
→
Value is reloaded to CR5n at second overflow.
Count clock
TM5n
CR5n
TCE5n
INTTM5n
TO5n
N
N + 1 N + 2
FFH 00H 01H
N
N + 1 N + 2
FFH 00H 01H 02H
N
02H
N
H
M
M M + 1 M + 2
<1> CR5n change (N
→
M)
<2>
Caution
When reading from CR5n between <1> and <2> in Figure 7-13, the value read differs from the
actual value (read value: M, actual value of CR5n: N).
7.5 Cautions for 8-Bit Timer/Event Counters 50 and 51
(1) Timer start error
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 8-bit timer counters 50 and 51 (TM50, TM51) are started asynchronously to the count clock.
Figure 7-14. 8-Bit Timer Counter 5n Start Timing
Count clock
TM5n count value
00H
01H
02H
03H
04H
Timer start
Remark
n = 0, 1