atmega323l ATMEL Corporation, atmega323l Datasheet - Page 44

• Manufacturer Part Number: atmega323l
• Description: Atmega323 8-bit Avr Microcontroller With 32k Bytes Of In-system Programmable Flash
• Manufacturer: ATMEL Corporation

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ATmega323(L)
Figure 31. Prescaler for Timer/Counter2
The clock source for Timer/Counter2 is named PCK2. PCK2 is by default connected to
the main system clock CK. By setting the AS2 bit in ASSR, Timer/Counter2 is asynchro-
nously clocked from the PC6(TOSC1) pin. This enables use of Timer/Counter2 as a
Real Time Counter (RTC). When AS2 is set, pins PC6(TOSC1) and PC7(TOSC2) are
disconnected from Port C. A crystal can then be connected between the PC6(TOSC1)
and PC7(TOSC2) pins to serve as an independent clock source for Timer/Counter2.
The Oscillator is optimized for use with a 32.768 kHz crystal. Applying an external clock
source to TOSC1 is not recommended. Setting the PSR2 bit in SFIOR resets the pres-
caler. This allows the user to operate with a predictable prescaler.
XTAL1
PSR2
CS20
CS21
CS22
AS2
CK
PCK2
Clear
TIMER/COUNTER2 CLOCK SOURCE
0
10-BIT T/C PRESCALER
TCK2
1457G–AVR–09/03