ATmega1281R231 Atmel Corporation, ATmega1281R231 Datasheet - Page 184

• Manufacturer Part Number: ATmega1281R231
• Manufacturer: Atmel Corporation

Specifications of ATmega1281R231

• Flash (kbytes): 128 Kbytes
• Max. Operating Frequency: 16 MHz
• Max I/o Pins: 54
• Spi: 3
• Twi (i2c): 1
• Uart: 2
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Crypto Engine: AES
• Sram (kbytes): 8
• Eeprom (bytes): 4096
• Operating Voltage (vcc): 1.8 to 3.6
• Timers: 6
• Frequency Band: 2.4 GHz
• Max Data Rate (mb/s): 2
• Antenna Diversity: Yes
• External Pa Control: Yes
• Power Output (dbm): 3
• Receiver Sensitivity (dbm): -101
• Receive Current Consumption (ma): 13.2
• Transmit Current Consumption (ma): 14.4
• Link Budget (dbm): 104

20.8
2549N–AVR–05/11
Asynchronous Operation of Timer/Counter2
Figure 20-10
Figure 20-10. Timer/Counter Timing Diagram, Setting of OCF2A, with Prescaler (f
Figure 20-11
Figure 20-11. Timer/Counter Timing Diagram, Clear Timer on Compare Match mode, with Pres-
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, OCR2x, and TCCR2x might be corrupted. A
safe procedure for switching clock source is:
1. Disable the Timer/Counter2 interrupts by clearing OCIE2x and TOIE2.
2. Select clock source by setting AS2 as appropriate.
3. Write new values to TCNT2, OCR2x, and TCCR2x.
4. To switch to asynchronous operation: Wait for TCN2UB, OCR2xUB, and TCR2xUB.
5. Clear the Timer/Counter2 Interrupt Flags.
6. Enable interrupts, if needed.
TCNTn
TCNTn
(clk
(clk
OCRnx
(CTC)
OCRnx
OCFnx
OCFnx
clk
clk
clk
clk
I/O
I/O
I/O
I/O
Tn
Tn
/8)
/8)
shows the setting of OCF2A in all modes except CTC mode.
shows the setting of OCF2A and the clearing of TCNT2 in CTC mode.
caler (f
clk_I/O
OCRnx - 1
TOP - 1
/8)
ATmega640/1280/1281/2560/2561
TOP
OCRnx
OCRnx Value
TOP
BOTTOM
OCRnx + 1
BOTTOM + 1
OCRnx + 2
clk_I/O
/8)
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