ATmega1281 Atmel Corporation, ATmega1281 Datasheet - Page 45

• Manufacturer Part Number: ATmega1281
• Manufacturer: Atmel Corporation

Specifications of ATmega1281

• Flash (kbytes): 128 Kbytes
• Pin Count: 64
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 54
• Ext Interrupts: 17
• Usb Speed: No
• Usb Interface: No
• Spi: 3
• Twi (i2c): 1
• Uart: 2
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 8
• Eeprom (bytes): 4096
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8 to 5.5
• Operating Voltage (vcc): 1.8 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 6
• Output Compare Channels: 16
• Input Capture Channels: 2
• Pwm Channels: 8
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

10.6
2549N–AVR–05/11
Low Frequency Crystal Oscillator
Table 10-6.
Notes:
The device can utilize a 32.768kHz watch crystal as clock source by a dedicated Low Frequency
Crystal Oscillator. The crystal should be connected as shown in
this Oscillator is selected, start-up times are determined by the SUT Fuses and CKSEL0 as
shown in
The Low-Frequency Crystal Oscillator provides an internal load capacitance, see
each XTAL/TOSC pin.
Table 10-7.
Device
Ceramic resonator, slowly
Ceramic resonator, slowly
ATmega640/1280/1281/2560/2561
Ceramic resonator, BOD
Crystal Oscillator, slowly
Ceramic resonator, fast
Ceramic resonator, fast
Crystal Oscillator, BOD
Crystal Oscillator, fast
Oscillator Source /
Power Conditions
rising power
rising power
rising power
rising power
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
enabled
enabled
Table 10-8 on page
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.
Start-up Times for the Full Swing Crystal Oscillator Clock Selection
Capacitance for Low Frequency Oscillator
Start-up Time from
46.
Power-down and
ATmega640/1280/1281/2560/2561
Power-save
32kHz oscillator
16K CK
16K CK
16K CK
258 CK
258 CK
1K CK
1K CK
1K CK
System Osc.
Timer Osc.
Additional Delay
14CK + 4.1ms
14CK + 4.1ms
14CK + 65ms
14CK + 65ms
Cap (Xtal1/Tosc1)
14CK + 4.1ms
14CK + 65ms
(V
from Reset
CC
14CK
14CK
= 5.0V)
18 pF
6 pF
(2)
Figure 10-2 on page
(1)
(2)
(1)
(2)
CKSEL0
Cap (Xtal2/Tosc2)
0
0
0
0
1
1
1
1
Table 10-7
8pF
6pF
43. When
SUT1:0
00
01
10
11
00
01
10
11
45
at