Datasheet

Section 5 Clock Pulse Generators
Rev. 1.50 Sep. 18, 2007 Page 83 of 584
REJ09B0240-0150
M
NM
NM
M + 1
M + α
t
A
(µs)
M - 1
φ
RC
FTIOA input
capture input
Timer RC
TRCCNT
GRA
GRC
Capture 1 Capture 2
M + α
Figure 5.8 Timing Chart of Trimming of On-Chip Oscillator Frequency
The on-chip oscillator frequency is obtained by the expression below. Since the input-capture
input is sampled at the rate of φ
RC
, the calculated result includes a sampling error of ±1 φ
RC
clock
cycle.
φRC =
(M + α) − M
(MHz)
t
A
φRC: Frequency of divided on-chip oscillator clock (MHz)
t
A
: Cycle of reference clock (µs)
M: Timer RC counter value