Contents

2_Description 1_Features 3-Glossary 3_Power Supply 3_1_Digital Supply 3_2_Analog Supply 4_Connection of RESET Pin on AVRs 4_1_External RESET Switch 5_Connecting ISP Lines 5_1_SPI Programming Interface 5_1_1_Shared Use of SPI Programming Lines 5_2_JTAG Interface 5_2_1_Shared Use of JTAG Lines 5_3_PDI Interface 5_3_1_External Reset Circuitry 5_4_TPI Interface 5_4_UPDIInterface 6_Using Crystal and Ceramic Resonators 6_1_Selecting the Clock Source in the AVR 6_2_General About Crystals and Ceramic Resonators 6_3_Recommended Capacitor Values 6_4_Unbalanced External Capacitors 6_5_RTC Crystals 6_6_PCB Layout AVR042_Unused_XTAL_Pins 7_Example Layout 8_Revision History The Microchip Web Site Customer Change Notification Service Customer Support Microchip Devices Code Protection Feature Legal Notice Trademarks Quality Management System Certified by DNV Worldwide Sales and Service