Atmel STK502 manual Avr

Using the STK502 Top Module

2.6TOSC Switch Figure 2-14. TOSC Switch

On the ATmega169 the TOSC1 and TOSC2 lines are shared with XTAL1 and XTAL2. The TOSC switch selects whether the 32 kHz crystal on the STK502, or the XT1/XT2 signals from STK500 should be connected to these pins on the device.

Figure 2-15shows a simplified block schematic on how this is implemented.

Figure 2-15.TOSC Block Schematic

32 kHz

AVR

XTAL1/TOSC1

XTAL2/TOSC2

XT1

To

STK500

XT2

TOSC

Switch

2-10

STK502 User Guide

2528A–AVR–11/02