Detect touch on glass table

[sn4k3]

Hello,

I'm asking here if anyone got the solution for this, after many research i can't find a good solution to my problem.
So, i have a glass table, not thick with 0.4cm, i want to divide the table (20x20cm) in square and rows, i will say 8x8 (without cuts), each square i want to be able to detect a touch in that precise square. But all electronics and cables need to be placed on bottom/downside the table, so i want the top side clean and clear.

Any ideia how i can do that?
Thanks

[scotty101]

You could use a capacitive touch film as found on mobile phone screens.

[sn4k3]

thanks for your reply,

So, will "MPR121 Breakout V12 Capacitive Touch Sensor" - http://www.ebay.co.uk/itm/MPR121-Breako ... 1c430c9d2b works for my needs?
Since i need 64 buttons i will need to adquire 6 of that

You could use a capacitive touch film as found on mobile phone screens.

[ILikePi99]

Another idea would be to use vibration sensors.. Not sure how well it would work though...

[chris57100]

Hi,
Is your table transparent (or a little bit) ? If yes, maybe another solution could be to put under the table a camera connected to a Raspberry Pi and use OpenCV to detect finger's place with movement/color detection (for exemple the darkest spot in the picture could be a finger).
It's not too hard to perform using OpenCV library. Once detected you can calculate the position in the picture and deduce which button it is

[toxibunny]

thanks for your reply,

So, will "MPR121 Breakout V12 Capacitive Touch Sensor" - http://www.ebay.co.uk/itm/MPR121-Breako ... 1c430c9d2b works for my needs?
Since i need 64 buttons i will need to adquire 6 of that

You could use a capacitive touch film as found on mobile phone screens.

They look excellent. You can make the actual sensor pads out of metal foil/tape stuck to the underside of the glass.

[sn4k3]

thanks for your reply,

So, will "MPR121 Breakout V12 Capacitive Touch Sensor" - http://www.ebay.co.uk/itm/MPR121-Breako ... 1c430c9d2b works for my needs?
Since i need 64 buttons i will need to adquire 6 of that

You could use a capacitive touch film as found on mobile phone screens.

They look excellent. You can make the actual sensor pads out of metal foil/tape stuck to the underside of the glass.

That all i need to hear

Since i only can have 4 MPR121 working with Pi on each SPI Address (0x5A - 0x5D), how can i increase or add more SPIs to support the 6 controlleres that i need?

Thanks

[toxibunny]

I think It's i2c, not spi.
If it was me, I'd probably involve a couple of cheap ebay arduino pro micros, or something of that sort. link them together, have 3 modules into each, then have one of them pass all the info to the raspi via UART.

others will no doubt have smarter solutions. also, don't forget to read,my sig.

[sn4k3]

I think It's i2c, not spi.
If it was me, I'd probably involve a couple of cheap ebay arduino pro micros, or something of that sort. link them together, have 3 modules into each, then have one of them pass all the info to the raspi via UART.

others will no doubt have smarter solutions. also, don't forget to read,my sig.

yes i2c, sorry.
I have some but i want to use something like a small chip to expand instead of a arduino is that possible?

Ahah nice sig

Thanks

[toxibunny]

http://www.sparkfun.com/products/9056

This seems to be more like what you want, then. I googled 'i2c multiplexer' and found it in an arduino forum post.

What are you making, btw?

[sn4k3]

http://www.sparkfun.com/products/9056

This seems to be more like what you want, then. I googled 'i2c multiplexer' and found it in an arduino forum post.

What are you making, btw?

Thanks, i will take a look and search about it.

A simple checkers game, glass transparent table with RGB LED on bottom (8x8), so each square must be touch sensitive to do the moves.