03/25/2017 at 15:00 •
It's been a long time, but I have some good news:
09/20/2015 at 22:30 •
In this video you can see the assembled prototype running a simple demo test of the touch sensors array:Hope you liked! :D
09/19/2015 at 18:55 •
Finally I finished the prototype, everything is working as expected, apart from the Bluetooth module (I still have to buy a new one). It was the most interesting build that I have done and I am pretty happy with it. Hope you like it:
This night I will be working on the software, so the new video will be up to date. Tomorrow I will post a simple video showing the progress and on Monday I post the new one. Thank you for your support!
09/19/2015 at 10:40 •
I’m only a few hours to finish the final prototype, but I wanted to share the current status with the community. Here are some photos from last night.
I’m still thinking in how I will be able to demonstrate in the new video the vibration of the pads. In the last video if you watch carefully I think you can notice the vibration but on last night’s test I wasn't able to tell which one was vibrating by looking at it, only by feeling and hear it. If you have some idea on how to show this on a visual demonstration please let me know!
09/19/2015 at 10:35 •
Here are some pictures of the assembling of 16 pads:
Note the little bumps made for reading the cell letter in Braille:
Making all these pads was a very time consuming task that took me almost five hours to finish. I had no time to make mistakes, luckily just one of the 80 very thin wires broke, but I was able to identify and fix it.
I used 5 minute Epoxy for keeping everything in place. I never had used it before, but the results was satisfactory.
09/16/2015 at 10:23 •
My test on the Bluetooth module did not work, It can send messages to my cellphone but it always receive “0” when I try to reply them (displayed as a blank line after the letter in the image below).
Oddly I found that every time that I sent a “y” it returned a “@”, this made me realize that it might be a software problem, but when I tried the same code in my Arduino Mega 2560 it worked... So I still don't know what it is all about, but I have some guesses:
- Maybe I overheated the uC during soldering
- Maybe the board has some design error (probably not due the simplicity of the track, see image below)
I also tried to make a serial connection between my Arduino Mega and the board and got the same results.
I think this is a problem with this unity only, so tomorrow I will assemble another board and see if this is really the case.
If someone has an idea about what can it be, please share! ;)
UPDATE: I assembled a second board and got the same results, I also tried making a connection with my Arduino Mega again and it worked! So probably the problem is in Bluetooth module, but is still odd that it works perfectly with my Arduino Mega. Anyway, I bought another Bluetooth module, and I will resume my tests in the weekend.
08/28/2015 at 22:35 •
Yesterday I assembled the main board as expected, I used only one slot for the IO, making it capable of handling the first 8 tiles. I also assembled 4 tiles of random Braille letters.
The expected results were achieved, I tested the inputs and outputs using a simple program that reads the inputs and activate the vibration motor of the corresponding tiles.
08/25/2015 at 22:55 •
... but my new soldering iron only comes tomorrow, and my flux pen on Thursday, so probably by Friday I'll have some news.
Here are some pictures:
Version 1.0 vs 2.1
08/20/2015 at 19:51 •
The main cause that I wasn't able to build a improved prototype yet is the huge mistake of choosing the wrong footprint for the ULM2803. I couldn't find this component at my city so I wasn't able to check if it had the right size, only when it has been delivered from China one month later. So I had to create a new design and order it again, this time using my voucher from OSHPark.
I still had two months left for the construction of the prototype but I had troubles with customs and I couldn't get them on time before I left Brazil. These are some pictures of the boards that arrived in Brazil after my departure:
I'm now in Ireland, starting a scholarship programme in Computer Engineering. I'm loving this country, but until last week I didn't have a address to order things. My boards are now estimated to be delivered on 25 of August, so until there I have to wait.
There are two exciting new improvements in this version of the main board:
- You can populate the board according with the number of pads (input and output) that you will use, e.g. 8, 16, 24 or 32:
- A unusual footprint for the ULM2803 (8 outputs) made by me is used for enabling the use of an ULM2003 (7 outputs) if you want:
05/27/2015 at 22:20 •
I'm currently porting the PCB design for KiCad, increasing the TouchX board hardware openness! :D
2.0 version changelog:
- Added mounting holes
- Added some forgotten capacitors/resistors
- Changed position of the Bluetooth HC-06 module connector
- Added Bluetooth RX pin voltage divider selection jumper
- Fixed SOIC-18 footprint
Here are some 3D renderings of the board:
On the next project log I'll post the full schematics and PCB layout files ;)