ATMEGA644A-MU Atmel, ATMEGA644A-MU Datasheet - Page 97
ATMEGA644A-MU
Manufacturer Part Number
ATMEGA644A-MU
Description
IC MCU AVR 64K FLASH 44VQFN
Manufacturer
Atmel
Series
AVR® ATmegar
Specifications of ATMEGA644A-MU
Core Processor
AVR
Core Size
8-Bit
Speed
20MHz
Connectivity
I²C, SPI, UART/USART
Peripherals
Brown-out Detect/Reset, POR, PWM, WDT
Number Of I /o
32
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
44-VQFN Exposed Pad
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
- Current page: 97 of 581
- Download datasheet (27Mb)
14.5.1
14.5.2
14.5.3
8272A–AVR–01/10
Force Output Compare
Compare Match Blocking by TCNT0 Write
Using the Output Compare Unit
Figure 14-3. Output Compare Unit, Block Diagram
The OCR0x Registers are 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 dou-
ble buffering is disabled. The double buffering synchronizes the update of the OCR0x Compare
Registers 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 OCR0x Register access may seem complex, but this is not case. When the double buffering
is enabled, the CPU has access to the OCR0x Buffer Register, and if double buffering is dis-
abled the CPU will access the OCR0x 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 (FOC0x) bit. Forcing Compare Match will not set the
OCF0x Flag or reload/clear the timer, but the OC0x pin will be updated as if a real Compare
Match had occurred (the COM0x1:0 bits settings define whether the OC0x pin is set, cleared or
toggled).
All CPU write operations to the TCNT0 Register will block any Compare Match that occur in the
next timer clock cycle, even when the timer is stopped. This feature allows OCR0x to be initial-
ized to the same value as TCNT0 without triggering an interrupt when the Timer/Counter clock is
enabled.
Since writing TCNT0 in any mode of operation will block all Compare Matches for one timer
clock cycle, there are risks involved when changing TCNT0 when using the Output Compare
Unit, independently of whether the Timer/Counter is running or not. If the value written to TCNT0
equals the OCR0x value, the Compare Match will be missed, resulting in incorrect waveform
164A/164PA/324A/324PA/644A/644PA/1284/1284P
bottom
FOCn
top
OCRnx
Waveform Generator
WGMn1:0
=
(8-bit Comparator )
DATA BUS
COMnX1:0
TCNTn
OCFnx (Int.Req.)
OCnx
97
Related parts for ATMEGA644A-MU
Image
Part Number
Description
Manufacturer
Datasheet
Request
R
Part Number:
Description:
Manufacturer:
Atmel Corporation
Datasheet:
Part Number:
Description:
Manufacturer:
ATMEL Corporation
Datasheet:
Part Number:
Description:
Manufacturer:
ATMEL Corporation
Datasheet:
Part Number:
Description:
IC AVR MCU 64K 16MHZ 5V 64TQFP
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
IC AVR MCU 64K 16MHZ 5V 64-QFN
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
IC AVR MCU 64K 16MHZ COM 64-TQFP
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
IC AVR MCU 64K 16MHZ IND 64-TQFP
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
IC AVR MCU 64K 16MHZ COM 64-QFN
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
MCU AVR 64KB FLASH 16MHZ 64TQFP
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
MCU AVR 64KB FLASH 16MHZ 64QFN
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
IC AVR MCU 64K 16MHZ IND 64-QFN
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
IC MCU AVR 64K 5V 16MHZ 64-TQFP
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
IC MCU AVR 64K 5V 16MHZ 64-QFN
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
MCU 8-Bit ATmega AVR RISC 64KB Flash 5V 64-Pin TQFP T/R
Manufacturer:
Atmel
Datasheet: