Developer "Dlloyd" has designed an Arduino IDE-compatible 12V high-voltage programmer for ATtiny parts which use the Unified Program and Debug Interface (UPDI) — and promises no fear of lockouts while experimenting with different configuration options.
"I was surprised that I couldn't find any simple, economical way to explore the multiple configurations of the UPDI programming pin (PA0) on these newer MCUs," Dlloyd writes. "I therefore decided to design this 12V HV UPDI programmer with design goals being low cost, highly reliable and seamless operation with these MCUs and the Arduino IDE."
"This product can automatically send the 12V UPDI enable sequence at power up and also at the start of the programming session. At the end of the programming session, it can automatically cycle target power to re-load any re-configured fuse settings. It uses an enhanced Dickson charge pump to create the 12V pulse allowing for a an effective, low cost solution. When it comes to enabling UPDI mode for programming, a product that 'just works' is a valuable asset."
Designed for use with an Arduino Nano, the programmer is compatible with the Arduino IDE and includes three programming modes: UPDI, HV, and Power Cycle HV (PCHV). The code is based on earlier work by Spence Konde, while Dlloyd's circuit design has been made available on OSH Park. Alternatively, Dlloyd has also published a DIY breadboard equivalent.