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Section 18 Multi-Function Timer Pulse Unit (MTU)
Rev. 4.00 Sep. 14, 2005 Page 628 of 982
REJ09B0023-0400
18.7.3 Caution on Period Setting
When counter clearing on compare match is set, TCNT is cleared in the final state in which it
matches the TGR value (the point at which the count value matched by TCNT is updated).
Consequently, the actual counter frequency is given by the following formula:
f =
Pφ
(N + 1)
Where f : Counter frequency
Pφ : Peripheral clock operating frequency
N : TGR set value
18.7.4 Conflict between TCNT Write and Clear Operations
If the counter clear signal is generated in the T2 state of a TCNT write cycle, TCNT clearing
takes precedence and the TCNT write is not performed.
Figure 18.71 shows the timing in this case.
Counter clear
signal
Write signal
Address
Pφ
TCNT address
TCNT
TCNT write cycle
T1
T2
N H'0000
Figure 18.71 Conflict between TCNT Write and Clear Operations