ATtiny24 Atmel Corporation, ATtiny24 Datasheet - Page 28

• Manufacturer Part Number: ATtiny24
• Manufacturer: Atmel Corporation

Specifications of ATtiny24

• Flash (kbytes): 2 Kbytes
• Pin Count: 14
• Max. Operating Frequency: 20 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 4
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 12
• Ext Interrupts: 12
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• 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: Yes
• Crypto Engine: No
• Sram (kbytes): 0.12
• Eeprom (bytes): 128
• 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: 2
• Output Compare Channels: 4
• Input Capture Channels: 1
• Pwm Channels: 4
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

6.2.4
6.2.5
28
ATtiny24/44/84
Low-Frequency Crystal Oscillator
Crystal Oscillator / Ceramic Resonator
To use a 32.768 kHz watch crystal as the clock source for the device, the low-frequency crystal
oscillator must be selected by setting CKSEL fuses to ‘0110’. The crystal should be connected
as shown in
For this oscillator start-up times can be set with the SUT fuses, as shown in
Table 6-7.
Notes:
The Low-frequency Crystal Oscillator provides an internal load capacitance, see
each TOSC pin.
Table 6-8.
XTAL1 and XTAL2 are input and output, respectively, of an inverting amplifier which can be con-
figured for use as an On-chip Oscillator, as shown in
ceramic resonator may be used.
Figure 6-3.
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
given by the manufacturer should be used.
SUT1:0
00
01
10
11
ATtiny24/44/84
1. These options should be used only if frequency stability at start-up is not important.
Device
Figure
Start-up Times for the Low-Frequency Crystal Oscillator Clock Selection
Capacitance for the Low-Frequency Crystal Oscillator
Crystal Oscillator Connections
from Power Down
Start-up Time
6-3. To find suitable capacitors please consult the manufacturer’s datasheet.
1K CK
1K CK
32K CK
(1)
(1)
32 kHz Osc.
System Osc.
Table 6-9
Type
C2
C1
Additional Delay
below. For ceramic resonators, the capacitor values
from Reset
64 ms
64 ms
4 ms
Reserved
(Xtal1/Tosc1)
XTAL2
XTAL1
GND
Figure 6-3
16 pF
Cap
Slowly rising power
Recommended usage
Fast rising power or BOD enabled
Stable frequency at start-up
Either a quartz crystal or a
Table
(Xtal2/Tosc2)
6 pF
8006K–AVR–10/10
Cap
6-7.
Table 6-8
at