USBtiny

USBtiny is a family of inexpensive, open-source USB in-system programmers used to program Atmel AVR microcontrollers. Built as small hobbyist boards, USBtiny programmers connect to a PC via USB and drive the SPI interface of an AVR target to burn flash and EEPROM, as well as to set fuse and lock bits. They are commonly used with avrdude on Windows, macOS, and Linux.

Hardware and operation: A USBtiny board typically includes a USB interface controller and a six-pin ISP header arranged for MOSI, MISO, SCK, RESET, VCC, and GND. The USB interface translates USB commands into AVR SPI programming operations, enabling direct in-circuit programming of the target device. The design emphasizes low cost and simplicity, and kits or assembled boards are widely available. Use cases include installing bootloaders on Arduino boards and programming standalone AVR chips.

Software support: The programmer is supported by avrdude, which provides a consistent command-line interface for reading and writing flash and EEPROM, as well as configuring fuse bits. The open-source nature of USBtiny has led to various clones and variants, but the core workflow of selecting the programmer and target device remains standard across implementations.

Variants and history: USBtiny originated as an open-source hardware project in the early 2000s and has since inspired multiple clones and adaptations that employ different USB implementations or microcontroller platforms. It remains popular in the DIY electronics and maker communities due to its affordability, simplicity, and broad software support.

See also: USBasp, AVRDUDE, AVRISP, in-system programming.