some general stuff about the AVR-DA, AVR-DB, AVR-DD and AVR-EA series

As I am just getting started with the "new" Microchip AVR-Dx series of microcontrollers which seem to be replacing the good old ATmega328 workhorse and its tiny and mega friends for me, I plan to collect some usefull notes here.

• DS18B20 - a library to use the 1-wire digital thermometer DS18B20
• lcd - a library for a HD44780-based alphanumeric display, based on Peter Fleury's LCD library
• lcd_i2c - a library to use an alphanumeric display with a serial I2C port extender board
• modbus_rtu - basic functionality for a RS485 Modbus/RTU slave
• nokia5110 - simple library for text and graphics on a Nokia 5110 LCD with 84x48 pixels

• pinouts - an overview over the pinouts of selected AVR-Dx chips
• UPDI + UART - a breadbaord UPDI programmer and UART interface

• UPDI Programmer - how to convert a USB-C UART module into an UPDI programmer and the attached pitfalls

• On both the AVR32DA28 and AVR128DA64, purchased in summer 2025, the RESET pin was disabled in the syscfg0 fuse register by default. This is in contrast to the corresponding section from both devices' datasheets. The value in the fuse register on both factory-new devices was 0xC0 and not 0xC8.

The default value given in this fuse description is the factory-programmed value, and should not be mistaken for the Reset value.

Setting the fuse to the correct value for enabling the reset pin can be done by avrdude -p32da28 -PCOM3 -cserialupdi -U syscfg0:w:0xc0:m