Bits 2 to 0—Timer Prescaler 2 to 0 (TPSC2 to TPSC0): These bits select the counter clock
source.
Bit 2
Bit 1
Bit 0
TPSC2
TPSC1
TPSC0
Function
0
0
0
Internal clock: ø
(Initial value)
1
Internal clock: ø/2
1
0
Internal clock: ø/4
1
Internal clock: ø/8
1
0
0
External clock A: TCLKA input
1
External clock B: TCLKB input
1
0
External clock C: TCLKC input
1
External clock D: TCLKD input
When bit TPSC2 is cleared to 0 an internal clock source is selected, and the timer counts only
falling edges. When bit TPSC2 is set to 1 an external clock source is selected, and the timer counts
the edge or edges selected by bits CKEG1 and CKEG0.
When channel 2 is set to phase counting mode (MDF = 1 in TMDR), the settings of bits TPSC2 to
TPSC0 in TCR2 are ignored. Phase counting takes precedence.
10.2.11 Timer I/O Control Register (TIOR)
TIOR is an 8-bit register. The ITU has five TIORs, one in each channel.
Channel
Abbreviation
Function
0
TIOR0
1
TIOR1
2
TIOR2
3
TIOR3
4
TIOR4
TIOR controls the general registers. Some functions differ in PWM
mode. TIOR3 and TIOR4 settings are ignored when complementary
PWM mode or reset-synchronized PWM mode is selected in
channels 3 and 4.
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