ATMEGA163 ATMEL [ATMEL Corporation], ATMEGA163 Datasheet - Page 39

• Manufacturer Part Number: ATMEGA163
• Description: 8-bit Microcontroller with 16K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

Timer/Counters
Timer/Counter
Prescalers
1142E–AVR–02/03
The ATmega163 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/Counter0 and
Timer/Counter1 have individual prescaling selection from the same 10-bit prescaler.
Timer/Counter2 has its own prescaler. Both these prescalers can be reset by setting the
corresponding control bits in the Special Functions I/O Register (SFIOR). 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 which triggers the counting.
Figure 30. Prescaler for Timer/Counter0 and Timer/Counter1
For Timer/Counter0 and Timer/Counter1, 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/Counter0 and Timer/Counter1, CK, external source, and stop can also be
selected as clock sources. Setting the PSR10 bit in SFIOR resets the prescaler. This
allows the user to operate with a predictable prescaler. Note that Timer/Counter1 and
Timer/Counter0 share the same prescaler and a Prescaler Reset will affect both
Timer/Counters.
PSR10
TCK1
Clear
ATmega163(L)
TCK0
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