ATMEGA128-16AU SL383 Atmel, ATMEGA128-16AU SL383 Datasheet - Page 137

• Manufacturer Part Number: ATMEGA128-16AU SL383
• Manufacturer: Atmel

Timer/Counter1
Control Register C –
TCCR1C
Timer/Counter3
Control Register C –
TCCR3C
2467S–AVR–07/09
Table 62. Clock Select Bit Description
If external pin modes are used for the Timer/Countern, transitions on the Tn pin will clock the
counter even if the pin is configured as an output. This feature allows software control of the
counting.
•
•
•
The FOCnA/FOCnB/FOCnC bits are only active when the WGMn3:0 bits specifies a non-PWM
mode. When writing a logical one to the FOCnA/FOCnB/FOCnC bit, an immediate compare
match is forced on the waveform generation unit. The OCnA/OCnB/OCnC output is changed
according to its COMnx1:0 bits setting. Note that the FOCnA/FOCnB/FOCnC bits are imple-
mented as strobes. Therefore it is the value present in the COMnx1:0 bits that determine the
effect of the forced compare.
A FOCnA/FOCnB/FOCnC strobe will not generate any interrupt nor will it clear the timer in Clear
Timer on Compare Match (CTC) mode using OCRnA as TOP.
The FOCnA/FOCnB/FOCnB bits are always read as zero.
•
These bits are reserved for future use. For ensuring compatibility with future devices, these bits
must be written to zero when TCCRnC is written.
Bit
Read/Write
Initial Value
Bit
Read/Write
Initial Value
CSn2
Bit 7 – FOCnA: Force Output Compare for Channel A
Bit 6 – FOCnB: Force Output Compare for Channel B
Bit 5 – FOCnC: Force Output Compare for Channel C
Bit 4:0 – Reserved Bits
0
0
0
0
1
1
1
1
CSn1
0
0
1
1
0
0
1
1
FOC1A
FOC3A
W
W
7
0
7
0
CSn0
FOC1B
FOC3B
0
1
0
1
0
1
0
1
W
W
6
0
6
0
Description
No clock source. (Timer/Counter stopped)
clk
clk
clk
clk
clk
External clock source on Tn pin. Clock on falling edge
External clock source on Tn pin. Clock on rising edge
FOC1C
FOC3C
I/O
I/O
I/O
I/O
I/O
W
W
5
0
5
0
/1 (No prescaling
/8 (From prescaler)
/64 (From prescaler)
/256 (From prescaler)
/1024 (From prescaler)
4
–
R
0
4
–
R
0
R
R
3
–
0
3
–
0
R
R
2
–
0
2
–
0
R
R
1
–
0
1
–
0
ATmega128
R
R
0
–
0
0
–
0
TCCR1C
TCCR3C
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