Some compilers are overzealous when the unary minus operates on an unsigned number, and issue a warning. In fact, -u is a perfectly valid unsigned for any unsigned u, and always has been from K&R C to C++20. -u is the same as ~u + 1. Unsigned numbers form a modulo group, where -u is the unique unsigned number that when added to u results in 0. It is true that neither u nor -u can be negative (because no unsigned number is) but that should not get a compiler to issue a warning about the completely legitimate use of -u.
AVRDUDE
AVRDUDE - AVR Downloader Uploader - is a program for downloading and uploading the on-chip memories of Microchip’s AVR microcontrollers. It can program the Flash and EEPROM, and where supported by the programming protocol, it can program fuse and lock bits. AVRDUDE also supplies a direct instruction mode allowing one to issue any programming instruction to the AVR chip regardless of whether AVRDUDE implements that specific feature of a particular chip.
AVRDUDE was originally written in 2003 by Brian S. Dean. Since 2006, AVRDUDE has been maintained by Jörg Wunsch, with the help of various contributors.
The latest version of AVRDUDE is always available here:
https://github.com/avrdudes/avrdude
Documentation
Documentation for current and previous releases is on Github Pages.
Getting AVRDUDE for Windows
To get AVRDUDE for Windows, install the latest version from the Releases page.
Alternatively, you may build AVRDUDE yourself from source.
Getting AVRDUDE for Linux
To install AVRDUDE for Linux, install the package avrdude by running the following commands:
sudo apt-get install avrdude
Alternatively, you may build AVRDUDE yourself from source.
Getting AVRDUDE for MacOS
On MacOS, AVRDUDE can be installed through Mac Ports.
Alternatively, you may build AVRDUDE yourself from source.
Using AVRDUDE
AVRDUDE is a command-line application. Run the command avrdude without any arguments for a list of options.
A typical command to program your HEX file into your AVR microcontroller looks like this:
avrdude -c <programmer> -p <part> -U flash:w:<file>:i
For instance, to program an Arduino Uno connected to the serial port COM1 with a HEX file called blink.hex,
you would run the following command:
avrdude -c arduino -P COM1 -b 115200 -p atmega328p -D -U flash:w:objs/blink.hex:i
There are many different programmers and options that may be required for the programming to succeed.
For more information, refer to the AVRDUDE documentation.