ATMEGA645-16AI Atmel, ATMEGA645-16AI Datasheet - Page 86

• Manufacturer Part Number: ATMEGA645-16AI
• Description: IC AVR MCU FLASH 64K 5V 64TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA645-16AI

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: SPI, UART/USART, USI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 53
• 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): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-TQFP, 64-VQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

14.2.2
14.3
2570M–AVR–04/11
Timer/Counter Clock Sources
Registers
The definitions in
Table 14-1.
The Timer/Counter (TCNT0) and Output Compare Register (OCR0A) are 8-bit registers. Inter-
rupt request (abbreviated to Int.Req. in the figure) signals are all visible in the Timer Interrupt
Flag Register (TIFR0). All interrupts are individually masked with the Timer Interrupt Mask Reg-
ister (TIMSK0). TIFR0 and TIMSK0 are not shown in the figure.
The Timer/Counter can be clocked internally, via the prescaler, or by an external clock source on
the T0 pin. The Clock Select logic block controls which clock source and edge the Timer/Counter
uses to increment (or decrement) its value. The Timer/Counter is inactive when no clock source
is selected. The output from the Clock Select logic is referred to as the timer clock (clk
The double buffered Output Compare Register (OCR0A) is compared with the Timer/Counter
value at all times. The result of the compare can be used by the Waveform Generator to gener-
ate a PWM or variable frequency output on the Output Compare pin (OC0A).
Compare Unit” on page 87.
(OCF0A) which can be used to generate an Output Compare interrupt request.
The Timer/Counter can be clocked by an internal or an external clock source. The clock source
is selected by the Clock Select logic which is controlled by the Clock Select (CS02:0) bits
located in the Timer/Counter Control Register (TCCR0A). For details on clock sources and pres-
caler, see
BOTTOM
MAX
TOP
“Timer/Counter0 and Timer/Counter1 Prescalers” on page
The counter reaches the BOTTOM when it becomes 0x00.
The counter reaches its MAXimum when it becomes 0xFF (decimal 255).
The counter reaches the TOP when it becomes equal to the highest
value in the count sequence. The TOP value can be assigned to be the
fixed value 0xFF (MAX) or the value stored in the OCR0A Register. The
assignment is dependent on the mode of operation.
Definitions of Timer/Counter values.
Table 14-1
for details. The compare match event will also set the Compare Flag
are also used extensively throughout the document.
ATmega325/3250/645/6450
99.
See “Output
T0
).
86