at90ls8535-8mi ATMEL Corporation, at90ls8535-8mi Datasheet - Page 32

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

Timer/Counters
Timer/Counter
Prescalers
32
AT90S/LS8535
The AT90S8535 provides three general-purpose Timer/Counters – two 8-bit T/Cs and
one 16-bit T/C. Timer/Counter2 can optionally be asynchronously clocked from an exter-
nal oscillator. This oscillator is optimized for use with a 32.768 kHz watch crystal,
enabling use of Timer/Counter2 as a Real-time Clock (RTC). Timer/Counters 0 and 1
have individual prescaling selection from the same 10-bit prescaling timer.
Timer/Counter2 has its own prescaler. These Timer/Counters can either be used as a
timer with an internal clock time base or as a counter with an external pin connection
that triggers the counting.
Figure 28. Prescaler for Timer/Counter0 and 1
For Timer/Counters 0 and 1, the four different prescaled selections are: CK/8, CK/64,
CK/256 and CK/1024, where CK is the oscillator clock. For the two Timer/Counters 0
and 1, CK, external source and stop can also be selected as clock sources.
Figure 29. Timer/Counter2 Prescaler
TOSC1
CS20
CS21
CS22
AS2
CK
PCK2
TCK1
TIMER/COUNTER2 CLOCK SOURCE
0
10-BIT T/C PRESCALER
TCK2
TCK0
1041H–11/01