mTouch capacitive sensing

[jrprogrammer]

I've looked at the Microchip "mTouch", capacitive demo board. One of the Microchip reps had one... It works well...
I looked at the Microchip website, which has a wealth of information, all written in C... I have no dislike for "C" but use PBP most of the time. Has anyone played with any PBP code doing the same thing?
Thanks,
Jim

[mister_e]

i don't have those sensor, but sure i'm willing to help if you provide me some link to.

[jrprogrammer]

It doesn't use any specific sensor, rather the comparators inside the PIC.. If there are many capacitive areas, they multiplex the comparator. Check this link out:
http://www.microchip.com/stellent/id...param=en535171

It tells all you want to know (and more) about the concept.

I've done 4 wire resistive touch controllers with a PIC, but this is much cheaper to implement. Just copper squares on the backside of a circuit board, with your PIC and such, on the top...

JR

[mister_e]

Seems pretty straight forward to me.

which pic do you plan to use?

[jrprogrammer]

Right now I'm thinking the PIC16F690 since it has two comparators and I have a Microchip demo board that's looking for a home... I've also used it's little brothers: 16F677's and 16F687's on other stuff..
Cheers,
JR

[Pedro Santos]

Hello

I look for a similar sensor solution "capacitive or inductive sensor".
My problem is it must usable for blind people too, to scan the area with the finger where the "Virtuall buttons" is, but to validate any sensor "button" i must press on the material like acryl or glass where the pcb is mounted behind.
Anyone a sugestion how to do that?

Thanks

Bst regards
Pedro

[mackrackit]

Hello

I look for a similar sensor solution "capacitive or inductive sensor".
My problem is it must usable for blind people too, to scan the area with the finger where the "Virtuall buttons" is, but to validate any sensor "button" i must press on the material like acryl or glass where the pcb is mounted behind.
Anyone a sugestion how to do that?

Thanks

Bst regards
Pedro

A quick thought might be to use a piece of pcb in place of the glass and etch leaving the Braille.

[Pedro Santos]

Hello mackrackit

I must design the "virtuall buttons" on the glass and the pcb is mounted behind, that is the problem than with normal capacitor sensor with the PIC
or Quantum IC's when a blind people scan with finger the area to find the desired buttons, validate all them, i need the same sensor technique but
validate only when make pressing on the glass.
Hope that with this explanation you can undestand what i mean
Sorry for my bad english

Regards
Pedro

[Ioannis]

I believe that touch buttons are not for the blind people. They usually touch everything to understand what is in front of them.

A true button is approrpiate fro this case.

Or, maybe, the blind person after scanning the area, will have to "press" 3 times the same button in order to validate his command, allong with a buzzer to confirm with audio.

Ioannis

[mackrackit]

Hello mackrackit

I must design the "virtuall buttons" on the glass and the pcb is mounted behind, that is the problem than with normal capacitor sensor with the PIC
or Quantum IC's when a blind people scan with finger the area to find the desired buttons, validate all them, i need the same sensor technique but
validate only when make pressing on the glass.
Hope that with this explanation you can undestand what i mean
Sorry for my bad english

Regards
Pedro

I follow you now. Was not thinking about scanning the buttons.
What about pressure sensitive membrane buttons? Use a piece of acetate with dimples punched from the back.

Your English is fine. My brain is slow

[aratti]

Pedro, your glass pannel could be mounted with retro springs (one at each corner). Place a microswitch in between that validate the choise. The microswitch could be activated only with a finger pressure that you can control using springs that will require the correct compromise between security and usability.

Another way could be to have a separate switch that should be pressed after that the disabled has found the requested command. A vocal staff could be activated after the selection has been made to tell which command has been chosen and to request the pressing of the abilitation command.

Al.

[Pedro Santos]

Hello Aratti

Can´t use it with springs, the glasspanel must mounted fixed with no movement.
It must exist another possibility, but no idea?

Regards
Pedro

[aratti]

if you don't want movement than you can use a Force Sensors, which will measure the pressure againt the pannel, and will anable the command only if the push reach your calibration.

Al.

[sougata]

Hi,

For the blinds http://en.wikipedia.org/wiki/Laser_engraving laser engraved switch marks can be really useful. Rather than actuating a key press you may give a feedback through some digitized sound (Beep, ISD, RomanBlack, VS101, whatever) while the user scans the buttons. Hold (2secs... or whatever), or tap+hold, double tap, mixture of anything goes for registering keypress.

[bcd]

Thinking about your application for blind people.

Would a scan of the buttons to find the active areas not normally be quite fast running of the hands across the device?

Maybe be having software that rejects presses if the previous two buttons next to the current one were also pressed within a fast time-out would allow you to have the scan ability but then also sense the actual button presses.

Might need to make the scan work from either direction as some may scan left to right and some right to left.

bill