Datasheet

Section 5 Clock Pulse Generator
Rev. 3.00 Sep. 10, 2007 Page 87 of 528
REJ09B0216-0300
M
NM
N M
M + 1
M + α
t
A
(µs)
M − 1
φRC
FTIOA0 input
capture input
Timer Z
TCNT
GRA_0
GRC_0
Capture 1 Capture 2
M + α
Figure 5.10 Timing Chart of Trimming of On-Chip Oscillator Frequency
The on-chip oscillator frequency is gained by the expression below. Since the input-capture input
is sampled by the φ
RC
clock, the calculated result may include a sampling error of ±1 cycle of the
φ
RC
clock.
φRC =
(M + α) − M
(MHz)
t
A
φRC: Frequency of on-chip oscillator (MHz)
t
A
: Period of reference clock (µs)
M: Timer Z counter value