ATmega1281R231 Atmel Corporation, ATmega1281R231 Datasheet - Page 41

• 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

10.2.2
10.2.3
10.2.4
10.2.5
10.3
2549N–AVR–05/11
Clock Sources
I/O Clock – clk
Flash Clock – clk
Asynchronous Timer Clock – clk
ADC Clock – clk
I/O
The I/O clock is used by the majority of the I/O modules, like Timer/Counters, SPI, and USART.
The I/O clock is also used by the External Interrupt module, but note that some external inter-
rupts are detected by asynchronous logic, allowing such interrupts to be detected even if the I/O
clock is halted. Also note that start condition detection in the USI module is carried out asynchro-
nously when clk
The Flash clock controls operation of the Flash interface. The Flash clock is usually active simul-
taneously with the CPU clock.
The Asynchronous Timer clock allows the Asynchronous Timer/Counter to be clocked directly
from an external clock or an external 32kHz clock crystal. The dedicated clock domain allows
using this Timer/Counter as a real-time counter even when the device is in sleep mode.
The ADC is provided with a dedicated clock domain. This allows halting the CPU and I/O clocks
in order to reduce noise generated by digital circuitry. This gives more accurate ADC conversion
results.
The device has the following clock source options, selectable by Flash Fuse bits as shown
below. The clock from the selected source is input to the AVR clock generator, and routed to the
appropriate modules.
Table 10-1.
Note:
ADC
FLASH
1. For all fuses “1” means unprogrammed while “0” means programmed.
Device Clocking Options Select
I/O
is halted, TWI address recognition in all sleep modes.
ASY
Low Frequency Crystal Oscillator
Calibrated Internal RC Oscillator
Internal 128kHz RC Oscillator
Low Power Crystal Oscillator
Full Swing Crystal Oscillator
Device Clocking Option
External Clock
Reserved
ATmega640/1280/1281/2560/2561
(1)
1111 - 1000
0111 - 0110
0101 - 0100
CKSEL3:0
0011
0010
0000
0001
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