ATMEGA8L-8PC Atmel, ATMEGA8L-8PC Datasheet - Page 120

• Manufacturer Part Number: ATMEGA8L-8PC
• Description: IC AVR MCU 8K LV 8MHZ COM 28-DIP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA8L-8PC

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 8MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 23
• Program Memory Size: 8KB (4K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 6x10b
• Oscillator Type: Internal
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 28-DIP (0.300", 7.62mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: ATMEGA8L8PC

Timer/Counter
Prescaler
Special Function IO
Register – SFIOR
120
ATmega8(L)
Figure 56. Prescaler for Timer/Counter2
The clock source for Timer/Counter2 is named clk
system I/O clock clk
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 independent clock
source for Timer/Counter2. The Oscillator is optimized for use with a 32.768kHz crystal. Apply-
ing an external clock source to TOSC1 is not recommended.
For Timer/Counter2, the possible prescaled selections are: clk
clk
Setting the PSR2 bit in SFIOR resets the prescaler. This allows the user to operate with a pre-
dictable prescaler.
• Bit 1 – PSR2: Prescaler Reset Timer/Counter2
When this bit is written to one, the Timer/Counter2 prescaler will be reset. The bit will be cleared
by hardware after the operation is performed. Writing a zero to this bit will have no effect. This bit
will always be read as zero if Timer/Counter2 is clocked by the internal CPU clock. If this bit is
written when Timer/Counter2 is operating in Asynchronous mode, the bit will remain one until
the prescaler has been reset.
Bit
Read/Write
Initial Value
T2S
/128, clk
TOSC1
clk
PSR2
CS20
CS21
CS22
T2S
R
AS2
7
–
0
I/O
/256, and clk
I/O
R
6
–
0
. By setting the AS2 bit in ASSR, Timer/Counter2 is asynchronously
T2S
clk
R
5
–
0
/1024. Additionally, clk
T2S
R
TIMER/COUNTER2 CLOCK SOURCE
4
–
0
Clear
0
ACME
R/W
T2S
3
0
10-BIT T/C PRESCALER
. clk
clk
T2S
T2S
T2
PUD
R/W
2
0
as well as 0 (stop) may be selected.
is by default connected to the main
PSR2
R/W
1
0
T2S
/8, clk
PSR10
R/W
0
0
T2S
/32, clk
SFIOR
2486Z–AVR–02/11
T2S
/64,