Table of Contents
Advertisement
Section 9 16-Bit Timer
When MDF is set to 1 to select phase counting mode, TCNT2 operates as an up/down-counter and
pins TCLKA and TCLKB become counter clock input pins. TCNT2 counts both rising and falling
edges of TCLKA and TCLKB, and counts up or down as follows.
Counting Direction
TCLKA pin
TCLKB pin
In phase counting mode channel 2 operates as above regardless of the external clock edges
selected by bits CKEG1 and CKEG0 and the clock source selected by bits TPSC2 to TPSC0.
Phase counting mode takes precedence over these settings.
The counter clearing condition selected by the CCLR1 and CCLR0 bits in TCR2 and the compare
match/input capture settings and interrupt functions of TIOR2, TISRA, TISRB, TISRC remain
effective in phase counting mode.
Bit 5—Flag Direction (FDIR): Designates the setting condition for the OVF flag in TISRC. The
FDIR designation is valid in all modes in channel 2.
Bit 5
FDIR
Description
0
OVF is set to 1 in TISRC when TCNT2 overflows or underflows
1
OVF is set to 1 in TISRC when TCNT2 overflows
Bits 4 and 3—Reserved: These bits cannot be modified and are always read as 1.
Bit 2—PWM Mode 2 (PWM2): Selects whether channel 2 operates normally or in PWM mode.
Bit 2
PWM2
Description
0
Channel 2 operates normally
1
Channel 2 operates in PWM mode
When bit PWM2 is set to 1 to select PWM mode, pin TIOCA
output goes to 1 at compare match with GRA2, and to 0 at compare match with GRB2.
Rev. 4.00 Jan 26, 2006 page 340 of 938
REJ09B0276-0400
Down-Counting
High
Low
High
Up-Counting
Low
Low
High
becomes a PWM output pin. The
2
High
Low
(Initial value)
(Initial value)
Advertisement
Table of Contents
