Datasheet

Section 12 8-Bit Timers
Rev. 4.00 Sep 27, 2006 page 366 of 1130
REJ09B0327-0400
16-Bit Count Mode
When bits CKS2 to CKS0 in TCR0 are set to B'100, the timer functions as a single 16-bit timer
with channel 0 occupying the upper 8 bits and channel 1 occupying the lower 8 bits.
• Setting of compare-match flags
 The CMF flag in TCSR0 is set to 1 when a 16-bit compare-match occurs.
 The CMF flag in TCSR1 is set to 1 when a lower 8-bit compare-match occurs.
• Counter clear specification
 If the CCLR1 and CCLR0 bits in TCR0 have been set for counter clear at compare-match,
the 16-bit counter (TCNT0 and TCNT1 together) is cleared when a 16-bit compare-match
occurs. The 16-bit counter (TCNT0 and TCNT1 together) is cleared even if counter clear
by the TMRI0 pin has also been set.
 The settings of the CCLR1 and CCLR0 bits in TCR1 are ignored. The lower 8 bits cannot
be cleared independently.
• Pin output
 Control of output from the TMO0 pin by bits OS3 to OS0 in TCSR0 is in accordance with
the 16-bit compare-match conditions.
 Control of output from the TMO1 pin by bits OS3 to OS0 in TCSR1 is in accordance with
the lower 8-bit compare-match conditions.
Compare-Match Count Mode
When bits CKS2 to CKS0 in TCR1 are B'100, TCNT1 counts compare-match A’s for channel 0.
Channels 0 and 1 are controlled independently. Conditions such as setting of the CMF flag,
generation of interrupts, output from the TMO pin, and counter clearing are in accordance with the
settings for each channel.
Usage Note
If the 16-bit count mode and compare-match count mode are set simultaneously, the input clock
pulses for TCNT0 and TCNT1 are not generated and thus the counters will stop operating.
Simultaneous setting of these two modes should therefore be avoided.