Published December 25, 2020 © GPL3+

External UPDI Programmer for AVR-IoT WG Board

Program an AVR-IoT WG board externally instead of the onboard debugger. I had to workaround as I bricked my nEDBG debugger on my AVR-IoT WG.

BeginnerProtip1 hour2,940

External UPDI Programmer for AVR-IoT WG Board

Things used in this project

Hardware components

Microchip AVR-IoT WG Development Board

Arduino Nano R3

Software apps and online services

Arduino IDE

Hand tools and fabrication machines

Soldering iron (generic)

Wire Stripper & Cutter, 32-20 AWG / 0.05-0.5mm² Solid & Stranded Wires

Story

Introduction

Recently I received an AVR-IoT WG development board for the Smart Medical Design Challenge sponsored by Microchip.

When first trying to program the device, the Atmel Studio IDE prompted me to update the firmware of the on-board nEDBG debugger. Unfortunately, the debugger failed to be detected afterwards and remained stuck in bootloader mode.

I tried to restore the firmware many times but to no avail. After attempting for days, I decided to use an external programmer instead.

UPDI Programming Interface

On the AVR-IoT WG Board, is the Atmega4808 Microcontroller. It requires Unified Program and Debug Interface (UPDI) to program the chip. Many of the newer ATmega and ATtiny microcontrollers also use UPDI.

The Unified Program and Debug Interface (UPDI) is a one-wire interface for external programming and on-chip debugging of newer ATtiny and ATmega devices.

Because it requires only one wire, it is very easy for us to hook it up.

nEDBG debugger

As there are no debugging pins broken out on the board, let's first take a look at the schematic to plan where we need to solder.

The nEDBG has 3 interfaces which are the UPDI debugger, a USB CDC Virtual COM Port and a Data Gateway Interface (DGI).

We will only be soldering one wire for the UPDI so it's important to know that if we use the UPDI externally, we will not have access to the CDC and DGI interface.

Preparing the AVR-IoT Board

The UDPI signal is directly connected to pin 5 of the on-board debugger and resistor R110.

On the actual board, this is the point to solder.

1 / 2

Please be careful when soldering as that area is very tight in space. Note that the resistor is a 0402 package size and is very small.

As in this photo, I used 26AWG wire which is small enough to fit.

1 / 2

And from here on, you can connect that wire to your UPDI programmer.

Arduino as UPDI programmmer

For those on a budget, thankfully we can use the open-source project, jtag2updi. It is a piece of code that converts any Arduino (Uno/Nano) into a UPDI programmer.

Download this github repository to your PC first

https://github.com/ElTangas/jtag2updi

Open up jtag2updi.ino in Arduino IDE and flash it to the Arduino Nano board.

From here on, the Arduino Nano will act as a programmer

To program the AVR-IoT, we need to make some connections.

Wire up the Arduino D6 with a 4.7k resistor to AVR-IoT's UPDI point
Wire up the Arduino 5V/Gnd to the AVR-IoT's 5V/Gnd
Add 10uF capacitor between Arduino RST and GND. (Reason is to prevent auto-reset when acting as a programmer)

If needed, you can connect an external serial to USB converter to the RX/TX pins.

Verify connectivity

To check if the device is being detected correctly, we will make use of a command line tool called avrdude.

The Arduino software also comes with avrdude bundled together. It is found at "C:\Program Files (x86)\Arduino\hardware\tools\avr\bin".

In the jtag2updi folder, find avrdude.conf.

Copy the file .\avrdude.confinto the folder C:\Program Files (x86)\Arduino\hardware\tools\avr\bin

In this folder, do a Shift+Right Click and choose "Open command window here".

Run this command. Be sure to change COM4 to your COM port of the device. You can check which COM port number it is in the device manager.

avrdude -C .\avrdude.conf -c jtag2updi -P COM4 -p m4808

This command will read the device signature and we can confirm that it is the correct microcontroller

Subsequently, you can also build hex files from Atmel Studio and program it using avrdude with this command

avrdude -C .\avrdude.conf -c jtag2updi -P COM4 -p m4808 -U flash:w:"AVRIoTWGSensorNode.hex":i

Programming using Arduino IDE

For demonstration purposes, I will show how to program the AVR-IoT WG Board using Arduino IDE.

First, install the board files to program the ATmega4808.

We will use MegaCoreX by MCUDude

https://github.com/MCUdude/MegaCoreX

In the Arduino IDE, open File > Preferences and add this URL into the Additional Boards Manager URLs:

https://mcudude.github.io/MegaCoreX/package_MCUdude_MegaCoreX_index.json

Install MegaCoreX in Tools > Board > Boards Manager

Set the board to ATmega4808 for the AVR-IoT WG Board.

And select JTAG2UPDI as the programmer.

That's it for now! You can upload any sketch to confirm everything works!

I have attached an example blinky LED code for you to try out!

Code

Blinky for AVR-IoT WG Board

#define LED_RED            (PIN_PD0)
#define LED_YELLOW         (PIN_PD1)
#define LED_GREEN          (PIN_PD2)
#define LED_BLUE           (PIN_PD3)

void setup() {
  pinMode(LED_RED, OUTPUT);
  pinMode(LED_YELLOW, OUTPUT);
  pinMode(LED_GREEN, OUTPUT);
  pinMode(LED_BLUE, OUTPUT);
}

void loop() {
  digitalWrite(LED_RED, LOW);
  delay(100);
  digitalWrite(LED_YELLOW, LOW);
  delay(100);
  digitalWrite(LED_GREEN, LOW);
  delay(100);
  digitalWrite(LED_BLUE, LOW);
  delay(100);
  

  digitalWrite(LED_RED, HIGH);
  delay(100);
  digitalWrite(LED_YELLOW, HIGH);
  delay(100);
  digitalWrite(LED_GREEN, HIGH);
  delay(100);
  digitalWrite(LED_BLUE, HIGH);
  delay(100);
}

Credits

zst123

11 projects • 25 followers

An infocomm and electronics enthusiast. https://www.manzelseet.com

Thanks to ElTangas.

External UPDI Programmer for AVR-IoT WG Board

Things used in this project

Hardware components

Software apps and online services

Hand tools and fabrication machines

Story

Introduction

UPDI Programming Interface

nEDBG debugger

Preparing the AVR-IoT Board

Arduino as UPDI programmmer

Verify connectivity

Programming using Arduino IDE

Schematics

Pin Connections

Code

Blinky for AVR-IoT WG Board

Credits

zst123

Comments

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External UPDI Programmer for AVR-IoT WG Board

External UPDI Programmer for AVR-IoT WG Board

Things used in this project

Hardware components

Software apps and online services

Hand tools and fabrication machines

Story

Introduction

UPDI Programming Interface

nEDBG debugger

Preparing the AVR-IoT Board

Arduino as UPDI programmmer

Verify connectivity

Programming using Arduino IDE

Schematics

Pin Connections

Code

Blinky for AVR-IoT WG Board

Credits

zst123

Comments

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