STK600 includes several clock options for the target AVR.
A switch selects between the following three options:
z
Programmable clock generator
z
Crystal oscillator (with socket for a crystal)
z
XTAL1 Pin tri-stated (to be used with the AVR's internal RC oscillator)
Programmable Clock Generator
The programmable clock generator is set from the PC software. The frequency can be set from 1.1kHz to 32MHz with 0.5% accuracy.
To use the programmable clock generator as clock source, set the CLOCK switch to EXT position.
Crystal Oscillator
The on-board crystal oscillator will work with ceramic resonators or crystals between 4 and 24MHz (AT-cut, fundamental, and parallel resonant
crystals). Place a crystal in the crystal socket (located next to the PROGRAM button).
To use the crystal oscillator as a clock source, set the CLOCK switch to the XTAL position.
XTAL1 Pin Tri-stated
If the target AVR run on the internal oscillator, the XTAL1 pin can be disconnected from the clock sources on STK600.
To disconnect the XTAL1 pin, set the CLOCK switch to the INT position.
Real Time Clock
The STK600 also features a 32768 Hz oscillator, which can be used to make a real time clock. The output from the oscillator is available on the
32KHz pin on the AUX header. This clock can be routed to the TOSC1 pin on the target AVR by placing a jumper between the 32KHz and TOSC1
pin on the AUX header.
Page 20 of 35
STK600 User Guide
2008-06-20
file://C:\Documents and Settings\PAWEL\Ustawienia lokalne\Temp\~hhE369.htm
