Programming modern AVR microcontrollers #AVR #Programming @MicrochipMakes

Scott W Harden describes how to program Microchip’s newest series of AVR microcontrollers using official programming gear and software. He has spent many years programming the traditional series of Atmel chips, but now several years after Microchip acquired Atmel he’s interested in exploring the capabilities of the latest series of AVR microcontrollers (especially the new AVR DD family).

Currently the global chip shortage makes it difficult to source traditional ATMega and STM32 microcontrollers, but the newest series of ATTiny chips feature an impressive set of peripherals for the price and are available from all the major vendors.


  • Older AVR microcontrollers are programmed using in-circuit serial programming (ICSP) through the RESETSCKMISO, and MOSI pins using cheap programmers like USBtiny. However, serial programming is not supported on newer AVR microcontrollers.
  • New AVR microcontrollers are programmed using the unified program and debug interface (UDPI) exclusively through the UDPI pin. UDPI is a Microchip proprietary interface requiring a UDPI-capable programmer.
  • Official UDPI programmers include Atmel-ICE ($129) and MPLAB Snap ($35). The Atmel-ICE is expensive but it is very well supported. The MPLAB Snap is hacky, requires re-flashing, and has a physical design flaw requiring a hardware modification before it can program AVR series chips.
  • There are notable attempts to create alternative programmers (e.g., jtag2updi and pymcuprog), but this journey is arduous and fraught with complexity and brittleness (e.g., SpenceKonde/AVR-Guidance) so as painful as it is to buy new gear, I recommend just buying an official programmer.
  • UDPI programmers have a Vcc pin that is used to sense supply voltage (but not provide it), so you must power your board yourself while using one of these new programmers.

See the video below and more here.

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