A000003 Arduino, A000003 Datasheet - Page 32

• Manufacturer Part Number: A000003
• Description: MCU, MPU & DSP Development Tools MINI
• Manufacturer: Arduino
• Series: -r
• Type: MCUr

Specifications of A000003

• Processor To Be Evaluated: Atmega328
• Processor Series: ATmega
• Data Bus Width: 8 bit
• Interface Type: USB, RS-232
• Operating Supply Voltage: 7 V to 9 V
• Contents: Board
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• For Use With/related Products: ATmega168

8.5
8.6
32
Low Frequency Crystal Oscillator
Calibrated Internal RC Oscillator
ATmega48/88/168
The device can utilize a 32.768 kHz watch crystal as clock source by a dedicated Low Fre-
quency Crystal Oscillator. The crystal should be connected as shown in
Oscillator is selected, start-up times are determined by the SUT Fuses and CKSEL0 as shown in
Table
Table 8-7.
Note:
By default, the Internal RC OScillator provides an approximate 8.0 MHz clock. Though voltage
and temperature dependent, this clock can be very accurately calibrated by the user. The device
is shipped with the CKDIV8 Fuse programmed. See
more details.
This clock may be selected as the system clock by programming the CKSEL Fuses as shown in
Table
the pre-programmed calibration value into the OSCCAL Register and thereby automatically cal-
ibrates the RC Oscillator. The accuracy of this calibration is shown as Factory calibration in
Table 28-1 on page
By changing the OSCCAL register from SW, see
page
The accuracy of this calibration is shown as User calibration in
When this Oscillator is used as the chip clock, the Watchdog Oscillator will still be used for the
Watchdog Timer and for the Reset Time-out. For more information on the pre-programmed cali-
bration value, see the section
Power Conditions
BOD enabled
Fast rising power
Slowly rising power
BOD enabled
Fast rising power
Slowly rising power
36, it is possible to get a higher calibration accuracy than by using the factory calibration.
8-7.
8-8. If selected, it will operate with no external components. During reset, hardware loads
1. These options should only be used if frequency stability at start-up is not important for the
application.
Start-up Times for the Low Frequency Crystal Oscillator Clock Selection
305.
Start-up Time from
“Calibration Byte” on page
Power-down and
Reserved
Reserved
Power-save
32K CK
32K CK
32K CK
1K CK
1K CK
1K CK
“OSCCAL – Oscillator Calibration Register” on
Additional Delay
“System Clock Prescaler” on page 35
14CK + 4.1 ms
14CK + 65 ms
14CK + 4.1 ms
14CK + 65 ms
(V
from Reset
287.
CC
14CK
14CK
= 5.0V)
Table 28-1 on page
(1)
(1)
(1)
Figure
CKSEL0
0
0
0
0
1
1
1
1
8-2. When this
2545S–AVR–07/10
305.
SUT1..0
00
01
10
00
01
10
11
11
for