Hello! This is my first post on this website. Very Happy

I'm excited to share a project that I've been working on recently.
I have designed a PCB to specifically fit the dimensions of the Mini USB footprint on the ti-84. It is capable of both data and power, works in either orientation and from a USB-C to USB-C cable.

YouTube video:
GitHub repository: https://github.com/lightcreations/ti84-usbc

ABOUT OTG:
This PCB does not have OTG functionality BUT I managed to squeeze the TUSB320 onto this PCB in the second version which converts the USB-C CC signal to the OTG ID equivalent. Expect an update post in a few days when I receive the new PCBs and parts.

OTG version (currently untested):

I commented on YouTube already, but this is super cool! If you don't mind, where did you purchase the parts from, and about how much would you estimate the project to cost? I look forward to hearing how the second version goes, good luck Smile
TIny_Hacker wrote:
I commented on YouTube already, but this is super cool! If you don't mind, where did you purchase the parts from, and about how much would you estimate the project to cost? I look forward to hearing how the second version goes, good luck Smile


I purchased the PCB from JLCPCB, they manufacture great quality pcbs for super cheap. You can get 5 of these PCBs for about $5, including shipping if you choose the global direct line option ($1). For the other parts, I used DigiKey. You can get a USB-C receptacle for about 70 cents and other parts like resistors for dirt cheap. I tend to add several items to my cart before checking out as shipping is a little more pricey that JLCPCB. Mouser is a great option as well.
Thanks for sharing this project here, Light Creations! Given TheLastMillennial's and others' work on this topic, I'm glad someone actually tried out the solution in that thread. Incidentally, I almost always use OSHPark for their high quality, low price, and fast shipping, but you inspired me to finally give JLCPCB a try for even cheaper to see how the quality compares for my prototyping iteration on a current project.
*bump* How's this going? I finally had a chance to watch the video through without skimming: very nice work, both on the video and on the soldering! I am impressed. What do you use to make your videos, incidentally?
Just watched the video very nice. As Kerm said how is this going have you tested the otg version? Smile Also I'm considering ordering the board and doing this mod on my calc however I dont have a hot air station.
Hello Kerm & Jake, I appreciate your kind words. I apologize for the delayed response (I just saw these posts). I've been very busy with other projects recently which caused me to become sidetracked from this one. I will update you in a few days when the mod is done. In the meanwhile, the PCB files for OTG (UNTESTED!) are on the dev branch of the GitHub repository. About the video, I used the free version of DaVinci Resolve 18.
Light Creations wrote:
Hello Kerm & Jake, I appreciate your kind words. I apologize for the delayed response (I just saw these posts). I've been very busy with other projects recently which caused me to become sidetracked from this one. I will update you in a few days when the mod is done. In the meanwhile, the PCB files for OTG (UNTESTED!) are on the dev branch of the GitHub repository. About the video, I used the free version of DaVinci Resolve 18.


Cool thanks! Smile I hope to get the otg once its been tested. Smile
Just tested and it worked!

https://www.youtube.com/watch?v=tsFsmm-5AOw
https://imgur.com/a/ieO5Kd1
The assembly on the QFN TUSB320 looks pretty good, which makes me wonder if you hand-assembled that or not. You've got pretty big pads which could probably be done by hand with an iron and the capacitor looks hand-assembled because it's somewhat askew, but the QFN would still be a pretty challenging part to assemble and the type-C connector's pins are probably difficult to do by hand as well. How did you assemble it?
Both the TUSB320 and USB-C connector were soldered on with hot air and then touched up with a soldering iron
³
Light Creations wrote:

Nice I guess I need to purchase one now. Great job.
Edit: I dont have a hot air station just a soldering iron. I do have a heat gun. How difficult will it be without a hot air station? I might be able to pick one up or borrow one from a friend. Also I was looking at the github have your released the otg version?
GitHub release was created: https://github.com/lightcreations/ti84-usbc/releases/tag/v2
Having hot air is required to solder the mod PCB onto the calculator PCB and should also be used for removing the mini USB connector & soldering the QFN. I also definitely recommend you to practice using the hot air station on something else before your calculator
Light Creations wrote:
GitHub release was created: https://github.com/lightcreations/ti84-usbc/releases/tag/v2
Having hot air is required to solder the mod PCB onto the calculator PCB and should also be used for removing the mini USB connector & soldering the QFN. I also definitely recommend you to practice using the hot air station on something else before your calculator

Ok I will do that then. I might get someone else to do it though since I have never used hot air.
Hi there, I am a huge fan of this mod, and congratulations on achieving OTG support.

I have some feedback on your VDD jumper wire to TP29. I hooked up a 3.7V DC supply to my calculator's battery lines (real life reading of 3.75V) and then I took voltage measurements on all of the surrounding components. Below is the link to the photo.

https://imgur.com/a/W8lr68o

The two readings marked in yellow are directly continuous with TP29 if you would like to solder to those pins, but I think the most opportune soldering point is the left-most 3.75V one. It is very close to the jumper pad, and I am sure in real life this pad can be treated as interchangeable with VBAT.

I will also likely publish a pull request to the GitHub using copper pours and silkscreen labeling, but this is a very nicely done project.

Please let me know if the alternate soldering points work!
Thanks for the feedback! Just connected it to the left most pad and it does seem to be working
  
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