ATTINY26L8SU SL383 Atmel, ATTINY26L8SU SL383 Datasheet - Page 71

• Manufacturer Part Number: ATTINY26L8SU SL383
• Description: MCU 8-Bit ATtiny AVR RISC 2KB Flash 3.3V/5V 20-Pin SOIC T/R
• Manufacturer: Atmel

1477J–AVR–06/07
Figure 40. Timer/Counter1 Block Diagram
Three status flags (overflow and compare matches) are found in the Timer/Counter
Interrupt Flag Register – TIFR. Control signals are found in the Timer/Counter Control
Registers TCCR1A and TCCR1B. The interrupt enable/disable settings are found in the
Timer/Counter Interrupt Mask Register – TIMSK.
The Timer/Counter1 contains three Output Compare Registers, OCR1A, OCR1B, and
OCR1C, as the data source to be compared with the Timer/Counter1 contents. In nor-
mal mode the Output Compare functions are operational with all three Output Compare
Registers. OCR1A determines action on the OC1A pin (PB1), and it can generate
Timer1 OC1A interrupt in normal mode and in PWM mode. Likewise, OCR1B deter-
mines action on the OC1B pin (PB3) and it can generate Timer1 OC1B interrupt in
normal mode and in PWM mode. OCR1C holds the Timer/Counter maximum value, i.e.,
the clear on compare match value. An overflow interrupt (TOV1) is generated when
Timer/Counter1 counts from $FF to $00 or from OCR1C to $00. This function is the
same for both normal and PWM mode. The inverted PWM outputs OC1A and OC1B are
not connected in normal mode.
In PWM mode, OCR1A and OCR1B provide the data values against which the
Timer/Counter value is compared. Upon compare match the PWM outputs (OC1A,
OC1A, OC1B, OC1B) are generated. In PWM mode, the Timer/Counter counts up to the
value specified in the Output Compare Register OCR1C and starts again from $00. This
feature allows limiting the counter “full” value to a specified value, lower than $FF.
Together with the many prescaler options, flexible PWM frequency selection is provided.
Table 37 lists clock selection and OCR1C values to obtain PWM frequencies from 20
kHz to 250 kHz in 10 kHz steps and from 250 kHz to 500 kHz in 50 kHz steps. Higher
PWM frequencies can be obtained at the expense of resolution.
8-BIT DATA BUS
COMPARE REGISTER
TIMER/COUNTER1
8-BIT COMPARATOR
REGISTER (TIMSK)
TIMER/COUNTER1
TIMER INT. MASK
T/C1 OUTPUT
T/C1 OVER-
FLOW IRQ
(OCR1A)
(TCNT1)
T/C1 COMPARE
MATCH A IRQ
T/C CLEAR
REGISTER (TIFR)
TIMER INT. FLAG
T/C1 COMPARE
MATCH B IRQ
COMPARE REGISTER
8-BIT COMPARATOR
T/C1 OUTPUT
(OCR1B)
(PB0)
OC1A
REGISTER 1 (TCCR1A)
REGISTER 1 (TCCR1A)
T/C1 CONTROL
T/C CONTROL
T/C CONTROL
OC1A
(PB1)
LOGIC
COMPARE REGISTER
8-BIT COMPARATOR
OC1B
(PB2)
T/C1 OUTPUT
(OCR1C)
ATtiny26(L)
REGISTER 1 (TCCR1B)
T/C CONTROL
OC1B
(PB3)
CK
PCK
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