ATMEGA649A-AU Atmel, ATMEGA649A-AU Datasheet - Page 150

IC MCU AVR 64K FLASH 64TQFP

ATMEGA649A-AU

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

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

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
ATMEGA649A-AU
Manufacturer:
Atmel
Quantity:
10 000
Part Number:
ATMEGA649A-AUR
Manufacturer:
Atmel
Quantity:
10 000
17.5.1
17.5.2
8284A–AVR–10/10
Force Output Compare
Compare Match Blocking by TCNT2 Write
Generator for handling the special cases of the extreme values in some modes of operation
(”Modes of Operation” on page
Figure 17-3
Figure 17-3. Output Compare Unit, Block Diagram
The OCR2A Register is double buffered when using any of the Pulse Width Modulation (PWM)
modes. For the Normal and Clear Timer on Compare (CTC) modes of operation, the double
buffering is disabled. The double buffering synchronizes the update of the OCR2A Compare
Register to either top or bottom of the counting sequence. The synchronization prevents the
occurrence of odd-length, non-symmetrical PWM pulses, thereby making the output glitch-free.
The OCR2A Register access may seem complex, but this is not case. When the double buffer-
ing is enabled, the CPU has access to the OCR2A Buffer Register, and if double buffering is
disabled the CPU will access the OCR2A directly.
In non-PWM waveform generation modes, the match output of the comparator can be forced by
writing a one to the Force Output Compare (FOC2A) bit. Forcing compare match will not set the
OCF2A Flag or reload/clear the timer, but the OC2A pin will be updated as if a real compare
match had occurred (the COM2A[1:0] bits settings define whether the OC2A pin is set, cleared
or toggled).
All CPU write operations to the TCNT2 Register will block any compare match that occurs in the
next timer clock cycle, even when the timer is stopped. This feature allows OCR2A to be initial-
ized to the same value as TCNT2 without triggering an interrupt when the Timer/Counter clock is
enabled.
ATmega169A/169PA/329A/329PA/649A/649P/3290A/3290PA/6490A/6490P
shows a block diagram of the Output Compare unit.
bottom
FOCn
top
OCRnx
152).
Waveform Generator
WGMn1:0
=
(8-bit Comparator )
DATA BUS
COMnX1:0
TCNTn
OCFnx (Int.Req.)
OCnx
150

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