Datasheet

Section 13 Timer W
Rev. 3.00 Mar. 15, 2006 Page 195 of 526
REJ09B0060-0300
Periodic counting operation can be performed when GRA is set as an output compare register and
bit CCLR in TCRW is set to 1.
When the count matches GRA, TCNT is cleared to H'0000, the IMFA flag in TSRW is set to 1. If
the corresponding IMIEA bit in TIERW is set to 1, an interrupt request is generated. TCNT
continues counting from H'0000. Figure 13.3 shows periodic counting.
TCNT value
GRA
H'0000
CST bit
IMFA
Time
Flag cleared
by software
Figure 13.3 Periodic Counter Operation
By setting a general register as an output compare register, compare match A, B, C, or D can
cause the output at the FTIOA, FTIOB, FTIOC, or FTIOD pin to output 0, output 1, or toggle.
Figure 13.4 shows an example of 0 and 1 output when TCNT operates as a free-running counter, 1
output is selected for compare match A, and 0 output is selected for compare match B. When
signal is already at the selected output level, the signal level does not change at compare match.
TCNT value
H'FFFF
H'0000
FTIOA
FTIOB
Time
GRA
GRB
No change No change
No change No change
Figure 13.4 0 and 1 Output Example (TOA = 0, TOB = 1)