ATMEGA649A-AU Atmel, ATMEGA649A-AU Datasheet - Page 160

• Manufacturer Part Number: ATMEGA649A-AU
• Description: IC MCU AVR 64K FLASH 64TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA649A-AU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: SPI, UART/USART, USI
• Peripherals: Brown-out Detect/Reset, LCD, POR, PWM, WDT
• Number Of I /o: 54
• Program Memory Size: 64KB (32K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 2K x 8
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-TQFP
• Processor Series: ATmega
• Core: AVR
• Data Bus Width: 8 bit
• Data Ram Size: 4 KB
• Interface Type: SPI, USART
• Maximum Clock Frequency: 16 MHz
• Number Of Programmable I/os: 54
• Number Of Timers: 3
• Operating Supply Voltage: 3.3 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Operating Temperature Range: - 40 C to + 85 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

17.9.1
8284A–AVR–10/10
Timer/Counter Prescaler
Figure 17-12. 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.
For Timer/Counter2, the possible prescaled selections are: clk
clk
Setting the PSR2 bit in GTCCR resets the prescaler. This allows the user to operate with a pre-
dictable prescaler.
ATmega169A/169PA/329A/329PA/649A/649P/3290A/3290PA/6490A/6490P
T2S
/128, clk
TOSC1
clk
PSR2
CS20
CS21
CS22
AS2
I/O
T2S
/256, and clk
IO
. By setting the AS2 bit in ASSR, Timer/Counter2 is asynchronously
clk
T2S
T2S
/1024. Additionally, clk
Clear
TIMER/COUNTER2 CLOCK SOURCE
T2S
0
. clk
10-BIT T/C PRESCALER
T2S
clk
T2S
T2
as well as 0 (stop) may be selected.
is by default connected to the main
T2S
/8, clk
T2S
/32, clk
T2S
/64,
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