VPN Remote Control Gadget

Make it easy to be more private on the internet and remote control the VPN settings on your ASUS RT-AC68U router.

This project creates a remote control from the Arduino-programmed LilyGo TTGO T5 V2.3 ESP32 e-paper microcontroller board and a custom-designed 3D-printed case.

Getting Started

Here is what you will need to build this project yourself:

ASUS RT-AC68U router, configured to use a VPN of your choice
LilyGo TTGO T5 V2.3 board
USB charger and/or small LiPo battery (look for model number 301525)

Programming the TTGO T5

You can find the Arduino sketch in the vpn_remote_control_gadget directory.

Copy this directory into your Arduino sketch directory.
Follow the instructions in the
LilyGo repository
to install Arduino libraries for the TTGO T5 V2.3 board.
Install the following Arduino libraries via the Arduino library manager:
Modify the credentials in file credentials_template.h
and rename the file to credentials.h.
Upload the sketch to the board!

Printing the Case

Send the file vpn_control_gadget_assembly_manuf.obj to a 3D printing place of your choice. The case is designed so it can be printed through SLS with PA 12 material and a rough finish. A vpn_control_gadget_assembly_manuf.stl file is also available, should your printing place not like .obj files.

Using the Gadget

To select a new VPN server or disconnect from the VPN, turn the TTGO T5 on using the slider on top of the case. Then, select a VPN with the button next to the slider. Once the checkmark appears in the bottom right of the screen, the request to change the VPN has been sent to the router. Now, you can turn off the gadget with the slider again. This helps to save battery.

Thanks to the e-paper display your choice will remain visible even when the device powers off.

Code Overview

The code on the Arduino talks to the ASUS router via POST requests. This is just like how the browser communicates with the ASUS configuration page when you are logged into the router configuration in your browser.

The code was only tested with RT-AC68U firmware version 3.0.0.4.385_20633. If you use a different firmware, this code may not longer work without adjustments.

All icons in the UI except for the arrow have been downloaded from flaticon.com and converted to an Arduino-readable file format via the LCD Image Converter.

CAD Overview

(see also on Thingiverse)

If you want to modify the case, you can find all CAD design files in the cad/design directory. You can open and edit the files in FreeCAD. The files were created in FreeCAD version 0.19-22492.

Mechanical Features

Lid: The case has a sliding lid on the back through which the microcontroller board can be inserted and removed. The lid is held in place by a pin. The pin unlocks when the lid is bent outward.

Buttons: The case has interfaces to 2 of TTGO T5's buttons. The lid features a cover for the button that is connected to channel IO39. The cover is connected to the case by a living hinge, avoiding any additional assembly. The case also provides an interface for the board's on/off slider. The slider is a removable part of the assembly, but stays in place thanks to a groove in the case's body once the board is assembled.

Assembly Notes

With the case, the TTGO T5 can be either used with a USB connection alone, or with a small LiPo battery. There is space for a 80 mAh battery in the case (search for model number 301525).

There are 6 cylindrical support pins that help the assembly stay in placing during printing. After printing, you need to remove these 6 pins to separate the model into its 3 parts. If printed with PA 12, these pins should be easy to cut with scissors, a knife, or simply bending until they break. To make sure all components slide and fit neatly, you should grind down any leftovers of the pins.

Once all components are separated, push the on/off slider component onto the on/off switch, insert the board into to case, and slide the lid shut.

Optionally, the case can be mounted on surfaces by means of double-sided tape.

Potential Design Improvements

The design presented here is functional. However, based on feedback from the very first 3d print of the gadget (see make on Thingiverse), there are a couple of improvements future makers may want to take on:

Tolerances of part are too large. During design, I was extra cautious to implement a +0.5 mm tolerance in all directions. This creates gaps that are too large, resulting in the PCB in the case sliding around and the slider originally not working. Filling material gets the job of fixing the PCB done and makes the slider workable (see red ellipses). Before printing, I would advise makers to add about 0.4 mm to the inner walls to restrict lateral movement of the PCB. Also consider that this may bring the e-paper screen further off-center, potentially hiding part of the screen.
Pushbutton casing component not properly dimensioned. The gap between the lower side of the case's pushbutton component is too far from the top of the actual pushbutton. This results in the user having to press the push button in the casing with a lot of force for the actual pushbutton to be actuated. I would advise adding about 0.5 mm to the inner-facing part of the push button component in the casing before printing (see orange arrow).
USB interface slot slightly misaligned. The USB interface slot should be positioned a little bit more (about 0.5 mm) to the left, looking from the bottom of the case, as in the picture above. While the current position works for connecting a USB charger, it is slightly off-center.
Case cover too thin. The sliding case cover, while functional, is subjectively too thin. It bends, making it hard for the pin that goes into the groove for closing the cover to stay in place. For future iterations, I would advise to deepen the groove for closing and to make the pin bigger. I would also advise to increase the thickness of the cover. Alternatively, I would add structural elements to the underside of the cover to improve its stiffness.

Contributing

For questions or feedback, please file an issue here on GitHub. Feel free to open pull requests for any changes you think the project could benefit from.

Credits

Code:

Used LilyGO starter sketch as a basis for communicating with e-paper display
WiFi Error icon, WiFi icon, VPN, and tick icon made by Freepik from www.flaticon.com
Hourglass icon made by Kiranshastry from www.flaticon.com

CAD:

The eye illustration on the back of the lid is part of Samuel Jessurun de Mesquita's print
"Zelfportret van alleen de ogen" (public domain, see here).