ATMEGA169V-8MU Atmel, ATMEGA169V-8MU Datasheet - Page 139
ATMEGA169V-8MU
Manufacturer Part Number
ATMEGA169V-8MU
Description
IC AVR MCU 16K 8MHZ 1.8V 64-QFN
Manufacturer
Atmel
Series
AVR® ATmegar
Specifications of ATMEGA169V-8MU
Core Processor
AVR
Core Size
8-Bit
Speed
8MHz
Connectivity
SPI, UART/USART, USI
Peripherals
Brown-out Detect/Reset, LCD, POR, PWM, WDT
Number Of I /o
54
Program Memory Size
16KB (8K x 16)
Program Memory Type
FLASH
Eeprom Size
512 x 8
Ram Size
1K 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-MLF®, 64-QFN
For Use With
ATAVRBFLY - KIT EVALUATION AVR BUTTERFLYATSTK502 - MOD EXPANSION AVR STARTER 500
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
- Current page: 139 of 365
- Download datasheet (4Mb)
Asynchronous Operation of
Timer/Counter2
2514P–AVR–07/06
When Timer/Counter2 operates asynchronously, some considerations must be taken.
•
•
•
•
•
•
Warning: When switching between asynchronous and synchronous clocking of
Timer/Counter2, the Timer Registers TCNT2, OCR2A, and TCCR2A might be
corrupted. A safe procedure for switching clock source is:
1. Disable the Timer/Counter2 interrupts by clearing OCIE2A and TOIE2.
2. Select clock source by setting AS2 as appropriate.
3. Write new values to TCNT2, OCR2A, and TCCR2A.
4. To switch to asynchronous operation: Wait for TCN2UB, OCR2UB, and
5. Clear the Timer/Counter2 Interrupt Flags.
6. Enable interrupts, if needed.
The CPU main clock frequency must be more than four times the Oscillator
frequency.
When writing to one of the registers TCNT2, OCR2A, or TCCR2A, the value is
transferred to a temporary register, and latched after two positive edges on TOSC1.
The user should not write a new value before the contents of the temporary register
have been transferred to its destination. Each of the three mentioned registers have
their individual temporary register, which means that e.g. writing to TCNT2 does not
disturb an OCR2A write in progress. To detect that a transfer to the destination
register has taken place, the Asynchronous Status Register – ASSR has been
implemented.
When entering Power-save or ADC Noise Reduction mode after having written to
TCNT2, OCR2A, or TCCR2A, the user must wait until the written register has been
updated if Timer/Counter2 is used to wake up the device. Otherwise, the MCU will
enter sleep mode before the changes are effective. This is particularly important if
the Output Compare2 interrupt is used to wake up the device, since the Output
Compare function is disabled during writing to OCR2A or TCNT2. If the write cycle
is not finished, and the MCU enters sleep mode before the OCR2UB bit returns to
zero, the device will never receive a compare match interrupt, and the MCU will not
wake up.
If Timer/Counter2 is used to wake the device up from Power-save or ADC Noise
Reduction mode, precautions must be taken if the user wants to re-enter one of
these modes: The interrupt logic needs one TOSC1 cycle to be reset. If the time
between wake-up and re-entering sleep mode is less than one TOSC1 cycle, the
interrupt will not occur, and the device will fail to wake up. If the user is in doubt
whether the time before re-entering Power-save or ADC Noise Reduction mode is
sufficient, the following algorithm can be used to ensure that one TOSC1 cycle has
elapsed:
1. Write a value to TCCR2A, TCNT2, or OCR2A.
2. Wait until the corresponding Update Busy Flag in ASSR returns to zero.
3. Enter Power-save or ADC Noise Reduction mode.
When the asynchronous operation is selected, the 32.768 kHz Oscillator for
Timer/Counter2 is always running, except in Power-down and Standby modes. After
a Power-up Reset or wake-up from Power-down or Standby mode, the user should
be aware of the fact that this Oscillator might take as long as one second to stabilize.
The user is advised to wait for at least one second before using Timer/Counter2
after power-up or wake-up from Power-down or Standby mode. The contents of all
Timer/Counter2 Registers must be considered lost after a wake-up from Power-
down or Standby mode due to unstable clock signal upon start-up, no matter
whether the Oscillator is in use or a clock signal is applied to the TOSC1 pin.
TCR2UB.
ATmega169/V
139
Related parts for ATMEGA169V-8MU
Image
Part Number
Description
Manufacturer
Datasheet
Request
R
Part Number:
Description:
IC AVR MCU 16K 16MHZ IND TQFP
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
IC AVR MCU 16K 16MHZ IND 64-QFN
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
IC AVR MCU 16K 16MHZ 5V 64TQFP
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
IC AVR MCU 16K 16MHZ 5V 64-QFN
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
8-bit Microcontroller with 16K Bytes In-System Programmable Flash
Manufacturer:
ATMEL [ATMEL Corporation]
Datasheet:
Part Number:
Description:
IC AVR MCU 16K 16MHZ IND 64QFN
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
IC AVR MCU 16K 16MHZ IND 64TQFP
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
IC AVR MCU 16K 16MHZ IND 64-QFN
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
IC AVR MCU 16K 16MHZ IND 64TQFP
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
Atmega169 8-bit With 16k Bytes Of In-system Programmable Flash
Manufacturer:
ATMEL Corporation
Datasheet:
Part Number:
Description:
Manufacturer:
Atmel Corporation
Datasheet:
Part Number:
Description:
IC AVR MCU 16K 16MHZ 5V 44TQFP
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
IC AVR MCU 16K 16MHZ 5V 44-QFN
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
IC AVR MCU 16K 16MHZ 5V 40DIP
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
MCU AVR 16K FLASH 16MHZ 44-QFN
Manufacturer:
Atmel
Datasheet: