SparkFun Forums

[radbrad]

I've been checking out the ability to add iPod style touch input to a project, and i've found a lot of information but can't quite connect all the dots. It seems like you need a sensor and then a chip to read the sensor material, such as CEM-1 or Indium-Tin-Oxide. From what I've gathered it looks like it's fairly simple on the production level, but nearly impossible on the prototype level. I can find out lots about the chips but don't know where to get the sensor, what kind of sensor to get, or how to connect the two together. Maybe you guys can make more sense of it?

Here's some chips from Quantum that look like they'd make pretty sweet breakout boards w/ sensor combo:

http://www.qprox.com/products/qslide_qt401.php - Capacitive Sensor Slider
http://www.qprox.com/products/qwheel_qt510.php - Capacitive Sensor Rotary wheel.

Analog has also come out with a similar chip, but i can't remember the name of it.

If anyone has any experience with or knows anything about this technology, please let me know!

Best regards,
Brad

[arm73c05]

"Apple chose Cypress when it switched from long-time supplier Synaptics Inc. to its own propriety solution for the Click Wheel."



http://arstechnica.com/reviews/hardware/nano.ars/4

http://www.cypress.com/CapSense

[PJE]

I'd also like to see a touch board. the issue is the layout/use mode.

Here's an Idea. Combine the 128x128 LCD board with an SPI driven Quantum QPROX 60168 which is a 16 key (4x4 matrix device).

have the PCB reverse mount the LCD so it's flush with the PCB surface. I'd only map out a 3x4 matrix to match the height of the display.

Code: Select all

+----------+ +-+-+-+-+
|          | | |^| | |
|          | +-+-+-+-+
|   LCD    | |<|O|>| |
|          | +-+-+-+-+
|          | | |V| | |
+----------+ +-+-+-+-+

This assembly would require the standard SPI interface with two chip select lines. It could then be bonded with the decal to the back of a piece of glass or plexiglass.

This would make a very nice (small) user interface, and could be also supplied mounted with a generic cursor, OK/Menu/Esc layout for mounting directly into the target system.

Thoughts...

PJE

[riden]

I like PJE's idea as well. I believe that there is a market for a product like this as well as well as a board sans the LCD (maybe a keyboard with one or two spin controls). It looks like it could be fabricated inexpensively and be quite affordable. It would take a lot of wear and tear, especially if a piece of acrylic covered everything. I've seen demos where the user touched nothing but the plexiglass cover -- no switches to wear out and no danger ruining your project by spilling a drink on it (well, practically no danger).

Ralph

[cctsm]

Well, PJE, I doubt that'd work too well - the touch interface things seem to work on a charge transfer method. The LCD has a lot of cells being charged and uncharged, and is in any case crisscrossed with transparent conductive paths.

The idea is good, tho.

[PJE]

Well, PJE, I doubt that'd work too well - the touch interface things seem to work on a charge transfer method. The LCD has a lot of cells being charged and uncharged, and is in any case crisscrossed with transparent conductive paths.

The idea is good, tho.

One application of the Quantum device is as a touchscreen over an LCD display using a transparent metalic oxide on the LCD glass... (see www.qprox.com).

The device works by detecting changes in the capacitance (from what I can gather).

On second thoughs, I'd separate the display and keypad and make a keypad which has a SPI passthrough connector for the existing LCD board. This gives the flexibility to run with different displays, but also allows a spacing between the PCBs (5mm?) to compensate for the LCD to get the LCD surface and keypad PCB surface in line.

Code: Select all

========PCB======
|    LCD    |  #<-connection
+-----------+ =====TOUCH PANEL======

PJE

[cctsm]

-- Yea, I probably misunderstood. I thought you suggested bonding it on the back of the display, not on the front.

[ZapWizard]

radbrad, Qprox's chips are VERY easy to use, and build with.

They are available from a variaty of suppliers which are linked on their website.
Click on Sales and Distribution at the bottom.

The IC's are VERY cheap for what they do.
QProx also has forums, and while meant for commercial customers, they are friendly and supportive of hobbiests.

I am implimenting both their Q-Wheel product, and Q-Touch products into my current PC modding project.
http://www.flickr.com/photos/zapwizard/sets/625883/

[JonChandler]

Zap,

How much trouble have you had adusting the sense capacitors? This is the part that scares me. IT seems like it takes a bit of tweaking to get things just right, so if I make a run of boards, I may find that I have to change the caps to suit the actual aplication, including panel thicknes and material.

Very pretty applications!

[ZapWizard]

Sorry for late reply, haven't been on the site.

I have their evaluation board, and adjusting the sensativity is NO problem!
I have the evaluation board working though 1/2" of wood with perfect results.

Their higher end chips use the same size caps, and adjust sensativity digitally.

[bsodmike]

Saw your nick and thought I'd drop by n' say hi. Long time no see (since the b-tech debacle)

I was thinking of using some Qtouch stuff in a few projects but never got around to it. Deffo gonna give it a try at some point hrm...