atmega3250v-8auatmega325v-8ai ATMEL Corporation, atmega3250v-8auatmega325v-8ai Datasheet - Page 141
atmega3250v-8auatmega325v-8ai
Manufacturer Part Number
atmega3250v-8auatmega325v-8ai
Description
Atmega3250 8-bit Microcontroller With In-system Programmable Flash
Manufacturer
ATMEL Corporation
Datasheet
1.ATMEGA3250V-8AUATMEGA325V-8AI.pdf
(362 pages)
- Current page: 141 of 362
- Download datasheet (7Mb)
18.10 Timer/Counter Prescaler
2570L–AVR–08/07
•
•
Figure 18-11. 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 C. 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 32.768 kHz crystal. If
applying an external clock on TOSC1, the EXCLK bit in ASSR must be set.
cycles, it executes the interrupt routine, and resumes execution from the instruction
following SLEEP.
Reading of the TCNT2 Register shortly after wake-up from Power-save may give an
incorrect result. Since TCNT2 is clocked on the asynchronous TOSC clock, reading TCNT2
must be done through a register synchronized to the internal I/O clock domain.
Synchronization takes place for every rising TOSC1 edge. When waking up from Power-
save mode, and the I/O clock (clk
value (before entering sleep) until the next rising TOSC1 edge. The phase of the TOSC
clock after waking up from Power-save mode is essentially unpredictable, as it depends on
the wake-up time. The recommended procedure for reading TCNT2 is thus as follows:
1. Write any value to either of the registers OCR2A or TCCR2A.
2. Wait for the corresponding Update Busy Flag to be cleared.
3. Read TCNT2.
During asynchronous operation, the synchronization of the Interrupt Flags for the
asynchronous timer takes 3 processor cycles plus one timer cycle. The timer is therefore
advanced by at least one before the processor can read the timer value causing the setting
of the Interrupt Flag. The Output Compare pin is changed on the timer clock and is not
synchronized to the processor clock.
TOSC1
clk
PSR2
CS20
CS21
CS22
AS2
I/O
IO
. By setting the AS2 bit in ASSR, Timer/Counter2 is asynchronously
clk
T2S
I/O
Clear
) again becomes active, TCNT2 will read as the previous
TIMER/COUNTER2 CLOCK SOURCE
ATmega325/3250/645/6450
T2S
0
. clk
10-BIT T/C PRESCALER
clk
T2S
T2
is by default connected to the main
141
Related parts for atmega3250v-8auatmega325v-8ai
Image
Part Number
Description
Manufacturer
Datasheet
Request
R
Part Number:
Description:
IC AVR MCU 32K 8MHZ 100TQFP
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
IC AVR MCU 32K 8MHZ 100TQFP
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
MCU AVR 32K FLASH 8MHZ 100TQFP
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
INTERVAL AND WIPE/WASH WIPER CONTROL IC WITH DELAY
Manufacturer:
ATMEL Corporation
Datasheet:
Part Number:
Description:
Low-Voltage Voice-Switched IC for Hands-Free Operation
Manufacturer:
ATMEL Corporation
Datasheet:
Part Number:
Description:
MONOLITHIC INTEGRATED FEATUREPHONE CIRCUIT
Manufacturer:
ATMEL Corporation
Datasheet:
Part Number:
Description:
AM-FM Receiver IC U4255BM-M
Manufacturer:
ATMEL Corporation
Datasheet:
Part Number:
Description:
Monolithic Integrated Feature Phone Circuit
Manufacturer:
ATMEL Corporation
Datasheet:
Part Number:
Description:
Multistandard Video-IF and Quasi Parallel Sound Processing
Manufacturer:
ATMEL Corporation
Datasheet:
Part Number:
Description:
High-performance EE PLD
Manufacturer:
ATMEL Corporation
Datasheet:
Part Number:
Description:
8-bit Flash Microcontroller
Manufacturer:
ATMEL Corporation
Datasheet:
Part Number:
Description:
2-Wire Serial EEPROM
Manufacturer:
ATMEL Corporation
Datasheet: