ATmega1281R231 Atmel Corporation, ATmega1281R231 Datasheet - Page 44

• 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

10.5
2549N–AVR–05/11
Full Swing Crystal Oscillator
Table 10-4.
Notes:
Pins XTAL1 and XTAL2 are input and output, respectively, of an inverting amplifier which can be
configured for use as an On-chip Oscillator, as shown in
crystal or a ceramic resonator may be used.
This Crystal Oscillator is a full swing oscillator, with rail-to-rail swing on the XTAL2 output. This is
useful for driving other clock inputs and in noisy environments. The current consumption is
higher than the
Oscillator will only operate for V
C1 and C2 should always be equal for both crystals and resonators. The optimal value of the
capacitors depends on the crystal or resonator in use, the amount of stray capacitance, and the
electromagnetic noise of the environment. Some initial guidelines for choosing capacitors for
use with crystals are given in
ues given by the manufacturer should be used.
The operating mode is selected by the fuses CKSEL3:1 as shown in
Table 10-5.
Note:
Crystal Oscillator, BOD
enabled
Crystal Oscillator, fast
rising power
Crystal Oscillator, slowly
rising power
Ceramic resonator, slowly
Frequency Range (MHz)
Ceramic resonator, fast
Oscillator Source /
Power Conditions
rising power
rising power
1. These options should only be used when not operating close to the maximum frequency of the
2. These options are intended for use with ceramic resonators and will ensure frequency stability
1. If 8MHz frequency exceeds the specification of the device (depends on V
0.4 - 16
device, and only if frequency stability at start-up is not important for the application. These
options are not suitable for crystals.
at start-up. They can also be used with crystals when not operating close to the maximum fre-
quency of the device, and if frequency stability at start-up is not important for the application.
Fuse can be programmed in order to divide the internal frequency by 8. It must be ensured
that the resulting divided clock meets the frequency specification of the device.
Start-up Times for the Low Power Crystal Oscillator Clock Selection (Continued)
Full Swing Crystal Oscillator operating modes
“Low Power Crystal Oscillator” on page
CKSEL3:1
Start-up Time from
Table 10-6 on page
Power-down and
011
CC
ATmega640/1280/1281/2560/2561
Power-save
= 2.7 - 5.5 volts.
16K CK
16K CK
16K CK
1K CK
1K CK
Recommended Range for Capacitors C1 and C2 (pF)
45. For ceramic resonators, the capacitor val-
Additional Delay
14CK + 4.1ms
14CK + 65ms
14CK + 4.1ms
14CK + 65ms
(V
from Reset
Figure 10-2 on page
CC
42. Note that the Full Swing Crystal
14CK
(1)
= 5.0V)
12 - 22
(2)
(2)
Table
CKSEL0
10-5.
CC
43. Either a quartz
0
1
1
1
1
), the CKDIV8
SUT1:0
11
00
01
10
11
44