Introducing the Serial-to-UPDI Programmer Featuring High Voltage (HV) Programming Capability

What Exactly is UPDI?

The Unified Program and Debug Interface (UPDI) represents a proprietary Microchip technology designed for the external programming and on-chip debugging of devices. As the advanced replacement for the traditional 4-wire SPI-based programming interfaces of the original AVRs, UPDI stands out with its streamlined single-wire, bi-directional interface, accessible through a single pin on the MCU.

Understanding High Voltage (HV) Programming

The flexibility of the UPDI pin allows it to be transformed into a GPIO pin. Similarly, the /RESET pin in the AVR DD series and newer MCUs can be modified for GPIO use. These modifications are achieved through the programming of specific user fuses. Without proper handling, it's possible to inadvertently disable both UPDI functionality and the /RESET feature, leading to an unprogrammable or even a bricked MCU. In this case, a high-voltage source is necessary to restore functionality, a task for which our programmer is specifically designed.

Our programmer offers the choice between HV and standard UPDI programming, easily selectable with a mode-switching slide switch.

As a Serial-to-UPDI converter, our device seamlessly integrates with any standard USB-to-Serial adapter that has an exposed DTR pin. A good example of a compatible adapter is this 6-pin CH-340 series USB-to-Serial adapter

Note: serial adapter is not included

Programming AVR DD-series (and newer series MCUs) with avrdude

Once connected, you can program the MCUs with avrdude. For example, for AVR16DD14:

avrdude -c serialupdi -P /dev/ttyUSB0 -p avr16dd14 -U flash:w:firmware.hex

Using HV mode

Remember to connect RESET pin of the programmer to /RESET pin on your MCU. Move slider to HV position. Use the following to enter terminal mode to reprogram problematic fuses (or just use the programmer normally):

avrdude -c serialupdi -P /dev/ttyUSB0 -p avr16dd14 -xrtsdtr=low -t