12/29/2025 5 PM - Decided on how to aproach the design challange

As a design constraint there is the Wio tracker L1 from Seed Studio.
It has an efficient nRF52 MCU, either OLED or Eink for the screen, and GPS. It has average power draw of about 10mA which is great. Enough about the HW.

I came up with these ideas:

• MT node that looks like a calculator. Ideal for texting in class, without teacher noticing.
• Kinda a hiker gadget. With helpful tools for hikers.
• Car housing so I can use it in a car. not cool enough
• Bombproof apocalyptic case. Total blud.

Oh wait I kinda love the hiker gadget!
What would a hiker need:

• Reliability
• GPS tracking of his/her mates
• All day battery life without worries about charging the battery
• This one is marketing: Solid antenna included with the Wio tracker L1
• Self contained so some kind of keyboard

That's it for rough design constraints.
I need to decide on where to position the components, and put more thought into the keyboard.

12/29/2025 9 PM - Placement thinking

Next I thought about rough placement of all components and elements.
So I opened my notepad and started sketching the rough shape.
The E-ink was of corse placed on top of the device with a keypad on the bottom.
One weird thing I needed to do is to place the solar panel on the back. That's because there is a lot of surface area on the back. But it's a a bit awkward as when using it or waiting for a notification the solar panel may receive little to none light.

Now let's talk design thought that went into the integrated keyboard.
My first instinkt was to take inspiration from the liligo blackberry keyboard that's on the Liligo T-deck. But it's small pitch makes it super fiddly and cumbersom to type on. Atlesat that's what makes sense and heard about it.
What would make bigger pitch and therefore make it better to type on? Less keys! So I took inspiration from Nokia T9 style keyboards. I found only one project that uses this type of keyboard.

Also I picked a rough dimensions. The Wio tracker is around 50x50 and the solar panel is 60x90. So I used 69x90 as a starting point. I'll probably have to change it a bit when I get to the actual design.

After a rough sketch I refined the device while being thoughtful about all of the components:

• Mother Board
  • It's 50x50
  • It has a E-ink screen attached to it
  • It has Lora and GPS antenna attachment points
  • It has navigation joystick
  • It has rst button, power button, two leds and USB-C
  • So everything revolves around this thing
• Keyboard
• Battery

So that's why I'm having the Wio Tracker L1 as a foundation stone. And let other things revolve around that.
The keyboard went just under the E-ink screen and navigation joystick.
Solar panel being on the back side.
The lora antenna made the best sense on the side of the antenna connector being on top ofc.
GPS antenna went on top as well but to the other side as it's going to have the best signal.

Next I'll make a rough shape in FreeCAD and get the 3D file of the Wio tracker.

12/30/2025 3:29 PM - Made the base

I started in CAD drawing the rough shape of the device. After that added the GPS bump. I chose a dimension that would make sense, as I don't really know the size. So I shot a message to SeedStudio. While waiting on a response I continued. Also added filets for better looks.

I skipped over how I did the modeling. For the XY inner dimensions I used Spreadsheet.Solar_panel_x variable and for the Y I set it to a value that made sense like 110. These are the same as the solat panel.
And set the wall thickness to 3mm

12/30/2025 3:50 PM - Added PCB mounting holes

Then, set the Thickness to 1.5mm with another variable and created a shell.

After that I set out on a quest to find and import the Wio's 3D model. It's on the Meshtastic design competition. But there is a problem as it's super detailed with all the little components. So I stipped it down in FreeCAD.

After getting the model. I started measuring it in prusa slicer and created a sketch. And after creating a sketch, I've extruded it.

Forgot to upload my drawing.

12/30/2025 4:46 PM - Added cutouts to the main boddy and sketched the solar panel

After I had the MB referenced, I started to make a cutout for the RST button, ON/OFF Button, USB-C, LEDs. The RST is reset so it doesn't get pressed on accident. As for the ON/OFF button I referenced the official eink case and made a little similar design.

And I took the button from the original case.

Also I sketched up the solar panel on the back.

12/30/2025 4:55 PM - Finalized the GPS holder

After that, I have finalized the GPS holder. The first dimensions were a little wonky because I didn't have the GPS's dimensions. Which is 15 x 15 x 4mm So I made it a little smaller and added two tabs to hold it in place.

12/30/2025 5:15 PM - Decided on a Solar panel and finalized its design

I already had one Solar panel I really liked. It's a 1.25W 5V one that's 69x110. So I chose this one for this project. And made a comparition in obsidian

After deciding which solar panel to use I made a cutout to route the cables.

12/30/2025 5:21 PM - Added mounting for the Lora antenna.

Started with sketching a hole, while taking measurements from an ipex to SMA adapter I have at home. Then made designed in a hex and fileted it for cleaner look.
After that I've modeled a simple antenna dummy model.

12/31/2025 10 AM - Added Mounting holes for screws

There were pretty straight forward besides the one over the MB.
I've started with searching what is a good diameter for M3 screws if I want them to screw directly into the plastic. It turns out it's 2.7mm.
As for the chamfers over the mother board these were a little more difficult as Chamfer tool didn't work as I wanted it to. So I made my own pocket with an andle.

12/31/2025 11:01 AM - Created a rough spape of the lid

After having enough work on the BASE, I've started the LID. I's derived from the BASE using a shape binder(For outer geometry) and a datum plane(Used to attach the LID to the BASE).

12/31/2025 11:36 AM - Work on the Keyboard/Keypad

My first thought was to use the CardKB or liligo T-keyboard.


But these have really small buttons. Which makes it super cumbersome to type on.
So My first attempt was with a standard keyboard, Kalih Choc switches. I was following this tutorial.

Here are my other references:
https://github.com/so1der/mesh_usb_keyboard
https://www.youtube.com/shorts/mPweixvhUAE

And choose a MCU that would be just enough for this. Which is the Attiny1616.

So I made this:


And it doesn't fit into the case. I even routed it all 😢. Its way too big.

Scrap that I built a new version

IDk how to mount it and the spacing is wierd.

Nice we have mounting holes here. But the buttons aren't square and the shape is weird.

So let's put a lot more thought into it and skip routing the PCB.

I didn't route it this time.
And it seems to work. BTW for V1 and three I tried to design in features for the mounting and the buttons.

The schematic is finished. But the PCB need to be routed as I didn't want to mess with it while figuring out the Layot. I'll do it later.

(5hr for CAD + 5hr for EDA)

1/1/2026 - Created a hole for the E-ink

Got the dimensions of a weirdly drawn datasheet. It's not readable. So I used for reference the official Eink case. And cross checked the dimensions with the Eink's datasheet.

I first did the pocket for the Eink screen. Then I did the frame around and the two little tabs to hold the screen. The cutout needed to be changed from centre to off centre after doing the frame.
And the BASE got support for the Eink.

This is the part I'm probably least proud of. I may change it later. It's tricky without the HW in hand.

1/2/2026 - Made a prototype

So after working on this project for a while, I felt overwhelmed. So I made a prototype out of Heltec V3 I've got FEL Camp. Which was wonderful BTW.

I have this solar power bank that my parents bought me like six years ago. (Their support is amazing BTW)
Threw out the old and damaged pack. Dremeled the window with plexiglass for protection.
Threw in a battery also from FEL Camp. And why not a buzzer for notifications. I was a little pitty that we didn't have the buzzer implemented back then, even though we needed it. 😅

And I played with it a little. Tried the materialize the overall shape that Travel Buddy is going to be.

When a sunny day got around. I put the solar panel in the sum and was hoping that the battery voltage wouldn't drop. But it slowly did. Also this panel is charging at unknown specs and the ESP32S3 is drawing around 100mA. I don't understand why makers of these meshtastic nodes uses such power hungry processors. So that's why I love the nRF52 on travel buddy.

1/7/2026 10:25 AM - Addded navigation buttons

Made a reference of the BODY. I'm going from the USB-C port. So I mesured the ofsets from the imperfectly placed main board.

Made the holes a bit similar to the reference cases. Because I have no idea on how big they should be.

Then I made the menu button thingi. No problems there. Maybe tolerances will show up later when I print it.

The joystic was a little bit more dificult. Because it need to fit within the hole and rock.
So I incresed the hole size a bit and after a lot of tweeking I managed to get it working. at lest on paper...
Then was the fun part of doing the knurling! My first design was supossed to be a cirkular design but the revolving I choose the wrong axis and I ended up with this cool design. Which fit great!

1/7/2026 10:32 AM - Added screw holes to the lid

Pretty self-explanatory.
I used the BASE with a Binder to use the screw holes as a reference.

I have no idea what else to write about.
Maybe that the screws are aranged in corners and in the middle to give a better support. But I probably talked about this when I made the mates.

1/7/2026 11 AM - Made a TPU protector

I've started with another binder for the BASE to have it as a reference. And made a sketch on the XY plane. The case needs to be a snug fit around the whole device. So I left no tolerance to the device. Oh and I used the shape binder to constrain the BASE silhouette. These kind of operations in FreeCAD are pain and take way too much time. You need to make a Shape Binder -> Sketch on the target body -> Reference it -> fight constraint and basic shapes. And when updating the geometry underneath everything breaks. AHH spent way too much time on these tasks.

And extruded it to make the rough shape.

Made a cutout for the antenna.

Then I started on the side buttons, connectors and LEDs.

Firstly I made a big cutout for these. But the protector should be to protect the HW and rn is not protecting anything. So I made a bumper for it.

The solar panel is a bit exposed so I raised the protector a bit and added like hook to make sure it doesn't slip off. - It's called lip BTW

Added filets. As they almost every time look sleek. :)

Now I need to do the hanger and with the bool cut it to size, and that will secure it even better.

1/11/2026 - Made a Hanger for the main body

I have no Idea on how to do the hook.
So I firstly made a datum plane in the middle and made a line of how the hanger should look. And then made a profile. Using additive helix it didn't work.
So I thought about it a bit more and realized that I can make it by having it ofset from the center and have the feature going through the center.
So I did that and it looks pretty good. Then I filleted the edges. Which was one advantage of the previous attempt.

Then I created a bool operation to remove material from the part so it will fit. Then I made a slot so the case can be pulled onto it.

1/15/2026 - Decided on a battery and calculated baterry life

So I thought more about battery life, and it's so promising!
The power efficient architecture makes this super long self-sustaining battery life possible.
The project is kinof finished so I chose a baterry and measured the max dimensions in FreeCAD.

• max battery size.
  • H<58mm
  • W<72mm
  • T<12mm

Unfortunately my selected panel got discontinued. RN I'm in school so I'll get this sorted later.

Anyways here are my calculations for baterry life.

Battery math

Power Consumption

Wio Tracker L1
10.5mW

Solar panel

Types	Wattage (mW)	Size (mm)	Price per one (czk)	Price per mW (czk)	With which will I go with	Link
6V100mA	600	60x90	20	0.033		10PCS X DC Solar Panel 6V 100mA 167mA 183mA 333mA 500mA 583mA 750mA Solar Battery cell phone charger portable - AliExpress 44
6V167mA	1000	60x110	45	0.045		10PCS X DC Solar Panel 6V 100mA 167mA 183mA 333mA 500mA 583mA 750mA Solar Battery cell phone charger portable - AliExpress 44
5V250mA	1250	69x110	35	0.028	This one !	10pcs 5V 1.25W 250mA Monocrystalline Silicon Epoxy Solar Panels Module Mini Solar Cells For Charging Cellphone Battery Wholesale - AliExpress 44
5V200mA	1000	61x107	154	0.154		Solar Panel 1W 5V 107*61mm 200mA Small Solar Panel for Cellular Phone Charger Home Light Toy Monocrystalline Silicon Solar Cell - AliExpress 44
5V200mA	1200	66x113	313	0.26		5V 1.2W Solar Panel - ETFE [Voltaic P124] : ID 5368 : Adafruit Industries, Unique & fun DIY electronics and kits

Charge time

Ideal conditions
Wio Tracker L1 Battery consumption 10.5mW

2Ah battery
3.7V nominal

1.25W solar panel

Calculate Wh
$$2[Ah]3.7[V]=7.4[Wh]$$
*Battery chargetime on solar**
Calculate charge time
$$7.4[Wh]/1.25[W]=5.9[h]$$
And unideal conditions the eficiency is around 70%
~10h
Or a day or two

Battery drain
$$7.4[Wh]/0.0105[W]=705[h]$$

1/20/2026 - Finished the PCB

So, I came back to finish the PCB.
After I made my T9-Keyboard project, I found out that there is support for TCA8418 IC in the Meshtastic codebase. Which is brilliant, as there is a keymap that's suitable for a 3x4 keyboard.

Although I took inspiration from the Chatter device. I love the simplicity of this approach. And it's already been done here: YT vid, and this is the product

So I researched the chip's datasheet with my own eyes and with the help of ChatGPT.
And I drew up the schematic with this knowledge. Assigned footprints and LCSC numbers.
And updated the schematic as I already had the buttons there.
Added the components on the back side. Souted while route tripping from the Pragues. We were with our electronics club, a part of the national technical museums program, and we were teaching kids how to solder. I've really enjoyed it.

And this part is finished.
The project is nearing completion.

1/24/2026 - Worked on branding, readme and some final touches

Even though the name is already great, "Travel Buddy", We aren't finished I need to do the BOM, readme, and other things for submission.

I went to add the Wio Tracker L1 eink to my shopping cart, but it's out of stock now.
So I'll use the OLED version. It will give me an idea of the project, and I may have a compatible screen.

JLC was pretty simple wo complications.

But the components were a different story as LCSC wanted a 3 USD handling fee on top of 13 bucks shipping. So I'll order the active components from Aliexpress and the passive ones I already have.

Oh I forgot to add in the Solar panel and the battery.
I have decided on a baterry earlier so it's staying as it is. Or maybe if I could find another bigger baterry, but it shouldn't be an issue thanks for the solar pannel.
And I got an idea to protect the solar pannel with plexiglass I already have at home it can be fun.

But the solar pannel somehow got discontinued or it can't be delivered to czech republic.
So I tried to find a compatible pannel but its isn't anywhere to be found.
Only thing I could find is another listing by the same store, but same problem.
https://www.aliexpress.com/item/32906698984.html
Only one I could find is a 60x110 1W one which as a bit smaller and less powerfull. But if this one works out great I should be able to make travel buddy a little smaller.
https://www.aliexpress.com/item/1005010294625335.html

I managed to find this one! It looks like the right one. Also these aren't in bulk nice.
By searching Solar Cell 5v 69 110
https://www.aliexpress.com/item/1005010712545664.html

Here is my ALi cart:

nope by refreshing I foun this out.

Hopefully it's the final Ali cart:


Aliexpress is so random.

And now the branding, readme and Bluprint finishing touches. I did all the things inreleavingly.
So I didn't like the tone of the one liner so I wrote a better one Pocketable, smart and sleek Meshtastic node. With keyboard, Eink screen, GPS and all day baterry life thanks to it's Solar panel and nRF52 in Wio tracker L1. the end is pretty rough so I cut it out on github but I left it in for higway.
I made a bom in readme and in the root directory. And another one in ods format to be a generic one.

I think that the readme came out great! Funny thing is that I'm able to write great technical texts like this one, but in school I struggle that our english teacher can't understand it at all. 😅

And now the only thing that reamins is to submit! Lets go

3/7/2026 - Ordering time

So today I've ordered everything needed for the project.
Some things vanished from aliexpress ... again. So I've updated the links almost everything was a bit cheaper neat. Also as were the PCBs.

3/23/2026 - It's alive!

So yesterday I was able to assemble it. And it fliping works! And the design is very smart in my opinion.

The previous week was super intensive with a lot of interesting stuff packed in. And in the meantime I was thinking about TravelBuddy, how nice it would be to carry TB around the city and sniff out the signals. Yeah I carried my pleb meshtastic node :]
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So I was pretty exited on friday as the battery and PCBs arrived on time to assemble it in the weeekend!! But hola we were at saturday heading back to Prage to go on an excursion around CT(Czech Television). And yeah it was super exiting and amazing as we've been there with a huge brodcast nerd. I'm so gratefull for this week.

Anyways after waking up on Sunday I went right back to work. I've began assembling the thing.
And there was a lot of mistakes made, but what you can't do with a dremel right :>
These mistakes are going to be mitigated in the next version. If I still have the time I'll do it in a next post.

First was the keyboard which was asembled almost without problems aside from the QFN packaged I2C keyboard multiplexer.

Then I noticed that the PCB doesn´t fit with the connector and also the groove conector wasn't jst but some other locking one so I needed to modify it.

Also the solar panel didn't fit so I've modified the case a bit using a dremel. That will be a future modification. Also the battery didn't fit.

Yeah and the menu button was way too long, the joystick button did print horibly on my printer.

But I was super exited about the power button as it fit nicely. Oh and the MB post came loose.

So it's held together by hopes ans prayers. At least for now!

When we got home I've labeled the T9 keyboard.

And after a day of school with it I'm really enjoying it!