Finished my BOM and sent and email

THANK YOU PCBWay for sponsoring this project!

I needed to lock in. I (mostly off-camera) worked on selecting parts for the BOM. This included the parts for the MicroDevUPDI Programmer, and the MicroDev128-32P.

I wrote a email to PCBWay (off-camera) asking if they will continue to sponsor me. (fingers crossed as the Hack Club grant just covered the first lot of parts).

Because Stardance ends in 2 weeks - and shipping and assembly takes more than 2 weeks this will be the last devlog on stardance :(

Thank you to all who have helped with this project - including you* reading this now. I really appreciate your support!

Finished the Rev1B and started work on the UPDI programmer

I finished work on the MicroDev128-32P Rev1B. It some new things that you can see in the past devlogs.

For MicroDevUPDI I made a simple USB to UPDI programmer. It uses the CH340E - which has an internal crystal. small footprint and needs few external parts. I added reverse polarity protection. It uses USB-C for its connector and is 2 small two layer board.

I changed the main MicroDev128 repo to be a main landing page - with each board having its own repo.

FINISHED Rev 1B

I finished this revision by adding a few things:

A full changelog bellow

• Rounded corners (idk just looks better in my opionion)
• Changed the TVS blows a fuse thing for a diode for proper reverse polarity protection
• Rearranged all the components
• Fixed some decoupling caps that were linked to GND and 5V but not even close to the acuall pin.
• Changed the UPDI header to be a 3x1 to save board space.
• As per request of a guy in my schools robotics club the board now fetures 3 neopixels (couldnt do his other request of a diode on every pin)
• Re-jigged the silkscreen labels so they should be acually readable
• Fixed the LT8653S being wired for burst mode ( which is great for battery life, but has higher ripple (I measured 30mV peak to peak with my scope) Now it is wired for FCM (Forced Countiuous Mode) for that super low ripple that the LT8653S is capable of.
• I learnt a thing or two about routing and made the pins for everything as close as possible to each other.

Most likely I forgot to mention some stuff that I changed ….

Anyway … turning out to be a genuinely useful board. Had the MVIO comunicating with a 3.3V SD card module yesterday no problems.

Until next time …

ILikeBWRs - Keegan Muller

Rearranging the power section

I started to rearange the power section of the board, making the layout of componenets better and in general improving the overall board layout. I added a big diode for reverse polarity protection. I also added neo pixels and are spliting the board more. I resized the UPDI header to bbe a 1x3 header with power on the outside - Ill put a full bridge recitifier on the programer so you can plug it in both ways.

Some Polishing

MicroDev128-32P

I noticed that my Rev 1B, is nearly completely different than my original design - so it merits a different board name. I am going to polish the MicroDev128-32P, make a programer for it then move on. I am adding USB to new board as well as some more fetures. The MicroDev128-32P will be polished so that it functions perfectly.
Also started more work on the docs!

Started work on MicroDev128-32P Rev 1B

I need to fix some flaws with the original design. I’ll address them as a list:

1. It doesn’t have onboard USB
2. It has small hard to read silkscreen and clearance issues.
3. It has an oversized programming header which can be ommited if I add onboard USB.
4. The 3PDT switch is big, easy to knock and takes up valuable board space.
5. The 603 Ceramic caps are large and are not in the best places for power filtering.

I plan to fix these all. Stay tuned to see what changes!

Ordered Parts, Assembled, and Tested

MicroDev128 Project

Quick recap:

I like the Arduino Nano but wow is it old. And outdated. And slow. And underpowered. So I put all my frustrations into making a board the same size (’cause trying to use a ESP32 on breadboard sucks when they are so thick) and waayyyyyyy more powerful. So then this thing was born. With a power regulator that can supply two times more current that my oscilloscope draws , mixed with the latest and greatest 8-bit AVR microcontrollers (not that 8-bit AVR microcontrollers are very new).

Sorry I haven’t devloged in a while so this is a lot of stuff in this devlog. This will say 1h 4min logged [because im really bad at remebering to devlog and I use my phone often that I can put Lookout on so I someone gets in the recordering I have to trash it :( ]

Day 1

I started by ordering parts from Digikey. I spend roughly 3 hours looking at part selections for the passives and LEDs.

Day 2

After the parts arrived I looked through the parts and then assebled one board. The caps placement was tricky because they all look the same size, so I’ll add a diagram to the Github repo in the future to make this easier.

Day 3

I tested the board and, well you can watch the video to see how it turned out.

So thats this updates devlog. See the Github repository for more info: github.com/ILikeBWRs/MicroDev128

WATCH THE VIDEO

Cleaning Up the PCB and getting it ready for production

Woooooo!!!!!!!!!!!!!!!!!!
Its done

Check the other MicroDev128-32P devlogs for more info.

I changed the short circuit/reverse polarity protection to using a TVS and fuse. I fixed some errors, worked on docs, and finished doing the silkscreen labels. Now I have to request funding and test (aka abuse it until it blows up >:] )
Sorry for gaps in the time-lapse, I got distracted reading my voltage regulator datasheet and forgot to pause the recording. Maaa Bad.

PCB Routing Pt3

Finally Finished Routing the project!!!!!!

Took a while but I ended up using layer 3 as a mixed power and signal plane insteed of a solid power plane. I am happy with how it turned out. I still might add TX and RX lines to the UPDI header, so you can do serial print.
Overall very happy. Now I have to finish the silkscreen labels, do the documentation :/ , and test it (yay).

PCB Routing
MicroDev128-32

Started routing everything for the whole board. I am sick of routing a good seeming line and then ripping it up 20 times.

• Started on the power lines
• Made planes for the GND and 5v lines
• Learnt that I really suck at PCB design in general

________________________________________________________________Project Overview

Based on the AVR128DB32, with the LT8653S switching power regulator. It has:

• Up to 2 amps on both the 3.3v and 5v lines.
• 128kB Flash and 16kB SRAM
• MVIO on 4-pins with 3.3v, 5v and EXTERNAL source presets
• UPDI Programing
• Arduino Nano sized footprint
• Aims to have a better price to performance ratio than
  Arduino (not hard considering a Genuine Uno is $40 NZD (About 20 USD)

More to come as I hopfully soon finish this project!

PCB PT2

This time:
I have changed the voltage regulator to be the LT8653S (smaller footprint)
I have relaid the board (again)
I have started routing some basic data lines and the crystal.
I have updated all footprints

More to go!
Getting there

Schematic Finishing and PCB (PT1)

Schematic PT2

Schematic AND ideas

Schematic Work and Pondering

Hardware figuring out

Block Diagram

A basic program “BLINK” for the bare chip I have.