atmega323l ATMEL Corporation, atmega323l Datasheet - Page 6

• Manufacturer Part Number: atmega323l
• Description: Atmega323 8-bit Avr Microcontroller With 32k Bytes Of In-system Programmable Flash
• Manufacturer: ATMEL Corporation

Clock Options
Internal RC Oscillator
Crystal Oscillator
6
ATmega323(L)
The device has the following clock source options, selectable by Flash Fuse bits as
shown:
Table 1. Device Clocking Options Select
Note:
The various choices for each clocking option give different start-up times as shown in
Table 6 on page 27.
The internal RC Oscillator option is an On-chip Oscillator running at a fixed frequency of
nominally 1 MHz. If selected, the device can operate with no external components. See
“Calibrated Internal RC Oscillator” on page 41 for information on calibrating this
Oscillator.
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 Figure 2. Either a quartz
crystal or a ceramic resonator may be used.
Figure 2. Oscillator Connections
Device Clocking Option
External Crystal/Ceramic Resonator
External Low-frequency Crystal
External RC Oscillator
Internal RC Oscillator
External Clock
1. “1” means unprogrammed, “0” means programmed.
C2
C1
(1)
XTAL2
XTAL1
GND
1111 - 1010
1001 - 1000
0111 - 0101
0100 - 0010
0001 - 0000
CKSEL3..0
1457G–AVR–09/03