Way back when, in the mists of time, the old 'freaks site had a pile of useful Design Notes. Some of them a now a bit dated but there is a wealth of useful information in them. They are, in theory, still available on the old site ( as long as it is online). To bring them to a wider audience's attention I'm posting them all here.
With thanks to fellow 'freaks sbennett, Bingo600, and Ntano for filling in some of the blanks.
DN001 Using STK500 to program external target STK300
DN002 Providing correct input voltage to the mega103L in STK300
DN003 AVR sleep modes
DN004 Common use of the AVR hardware UART
DN005 Using AVR Analog Voltage Reference (AREF)
DN006 AVR Memory Contents After Sleep and Reset
DN007 Little and Big Endian
DN008 Efficient I/O handling with bitfields
DN009 Using the ATtiny15 High-speed Timer
DN010 Manual AVRISP firmware upgrade
DN011 Manual JTAG ICE Firmware Update
DN012 Writing the Cal. Byte to the OSCCAL Reg in ImageCraft ICCtiny
DN013 Using ATmega8 Async. T/C Osc. with a 32 kHz X-tal on STK500
DN014 Flash Tables for AVRs without the LPM Instruction
DN015 Getting Started with the STK100 under Windows 95/98/NT/2000
DN016 How to distinguish ATmega128 from ATmega103
DN017 Calibrating the Internal RC Oscillator Using the STK500
DN018 Calibrating the Internal RC Oscillator
DN019 Upgrading the Firmware on STK500
DN020 Understanding AVR Fuses and Lock bits
DN021 Using the Built-in ADC in AVR
DN022 I/O Port Details
DN023 Programming Problems Using STK200/300 Programmer
DN024 Timer/Counter Basics
DN025 SPI Setup and Hold Times
DN026 Serial Port Connection
DN027 A Simple FSK modem Freq. Measuring and Generation
DN028 Using External SRAM with Small AVR Devices
DN029 FIFO Buffer - by Christoph Redecker
DN030 Frequency Synthesizer
DN031 Non-blocking Timers
DN032 AVR Boot Loader
DN033 DAC Utilizing ADC
DN034 IO Pin Config
DN035 Bidirectional SPI
DN036 Virtual Instrumentation
DN037 Custom Graphic LCD Characters
DN038 Fast Look-up Table Driven 16-bit CRC Routine
DN039 Sound Sample Play Back
DN040 Connecting an AVR Controller to CAN
DN041 Interfacing Parallel FRAM to AVR Microcontrollers
DN042 Efficient Handling of RS-485 Timing Issues
DN043 A String Display Routine
DN044 Using Trinary Encoding to Reduce Pin Wastage
DN045 Using Shift Registers to Increase the Number of I/O Pins
DN046 Timer Interrupt with a Maximum Accuracy
DN047 The Pin Adder
DN048 I2C Bus Sniffer
