at90ls8535-8mi ATMEL Corporation, at90ls8535-8mi Datasheet - Page 35

• Manufacturer Part Number: at90ls8535-8mi
• Description: 8-bit Microcontroller With 8k Bytes In-system Programmable Flash
• Manufacturer: ATMEL Corporation

16-bit Timer/Counter1
1041H–11/01
Figure 31 shows the block diagram for Timer/Counter1.
Figure 31. Timer/Counter1 Block Diagram
The 16-bit Timer/Counter1 can select clock source from CK, prescaled CK or an exter-
nal pin. In addition, it can be stopped as described in the specification for the
Timer/Counter1 Control Registers (TCCR1A and TCCR1B). The different status flags
(Overflow, Compare Match and Capture Event) and control signals are found in the
Timer/Counter1 Control Registers (TCCR1A and TCCR1B). The interrupt enable/dis-
able settings for Timer/Counter1 are found in the Timer/Counter Interrupt Mask Register
(TIMSK).
When Timer/Counter1 is externally clocked, the external signal is synchronized with the
oscillator frequency of the CPU. To assure proper sampling of the external clock, the
minimum time between two external clock transitions must be at least one internal CPU
clock period. The external clock signal is sampled on the rising edge of the internal CPU
clock.
The 16-bit Timer/Counter1 features both a high-resolution and a high-accuracy usage
with the lower prescaling opportunities. Similarly, the high prescaling opportunities
makes the Timer/Counter1 useful for lower speed functions or exact timing functions
with infrequent actions.
The Timer/Counter1 supports two Output Compare functions using the Output Compare
Register 1A and B (OCR1A and OCR1B) as the data sources to be compared to the
Timer/Counter1 contents. The Output Compare functions include optional clearing of
15
15
15
15
TIMER/COUNTER1 OUTPUT COMPARE REGISTER A
REGISTER (TIMSK)
TIMER INT. MASK
T/C1 INPUT CAPTURE REGISTER (ICR1)
T/C1 OVER-
FLOW IRQ
TIMER/COUNTER1 (TCNT1)
16 BIT COMPARATOR
8
8
8
8
T/C1 COMPARE
7
7
7
7
MATCHA IRQ
REGISTER (TIFR)
TIMER INT. FLAG
CAPTURE
TRIGGER
T/C1 COMPARE
MATCHB IRQ
0
0
0
0
REGISTER A (TCCR1A)
15
15
TIMER/COUNTER1 OUTPUT COMPARE REGISTER B
T/C CLEAR
T/C CLOCK SOURCE
UP/DOWN
CAPTURE IRQ
T/C1 CONTROL
T/C1 INPUT
16 BIT COMPARATOR
AT90S/LS8535
CONTROL
8
8
LOGIC
7
7
REGISTER B (TCCR1B)
T/C1 CONTROL
0
0
CK
T1
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