AVR Handheld Programmer 12V UPDI Adapter
UPDI interface is supported on X and V3 versions of Handheld Programmer only
New AVR ATtiny devices have UPDI programming interface. This is a 1-wire protocol that uses the Reset pin for programming. By default, new ATtiny microcontrollers have Reset pin configured as UPDI. This means that they can be programmed without applying 12V.
However, the user can use the device fuses to change Reset pin from UPDI to Reset function or to GPIO. If this is done, a 12V pulse must be applied to Reset pin to re-enable UPDI interface.
New ATmega devices with UPDI interface (ATmegaxx08/09) have a dedicated UPDI pin separate from Reset pin and do not ever need 12V entry.
This adapter provides 12V pulse to target to re-enable UPDI on ATtiny. It has standard Microchip UPDI 3 x 2 pin-out
We have found that this 12V UPDI method can give problems, especially on newer UPDI devices such as ATtiny16xx family. It is only 90% reliable and occasionally it seems to be chip dependent, i.e. some chips have more problems than others.
We do not recommend this adapter for production