ATmega88PA Automotive Atmel Corporation, ATmega88PA Automotive Datasheet - Page 157

• Manufacturer Part Number: ATmega88PA Automotive
• Manufacturer: Atmel Corporation

18.10 Timer/Counter Prescaler
9223B–AVR–09/11
Figure 18-12. Prescaler for Timer/Counter2
The clock source for Timer/Counter2 is named clk
main system I/O clock clk
nously clocked from the TOSC1 pin. This enables use of Timer/Counter2 as a Real Time
Counter (RTC). When AS2 is set, pins TOSC1 and TOSC2 are disconnected from Port B. A
crystal can then be connected between the TOSC1 and TOSC2 pins to serve as an indepen-
dent clock source for Timer/Counter2. The Oscillator is optimized for use with a 32.768kHz
crystal.
For Timer/Counter2, the possible prescaled selections are: clk
clk
selected. Setting the PSRASY bit in GTCCR resets the prescaler. This allows the user to oper-
ate with a predictable prescaler.
T2S
Atmel ATmega48PA/88PA/168PA [Preliminary]
/128, clk
PSRASY
TOSC1
clk
CS20
CS21
CS22
AS2
I/O
T2S
/256, and clk
IO
. By setting the AS2 bit in ASSR, Timer/Counter2 is asynchro-
clk
T2S
T2S
/1024. Additionally, clk
Clear
TIMER/COUNTER2 CLOCK SOURCE
0
T2S
10-BIT T/C PRESCALER
clk
. clk
T2
T2S
T2S
is by default connected to the
as well as 0 (stop) may be
T2S
/8, clk
T2S
/32, clk
T2S
/64,
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