touch sensing using AVR and not Microchip mcus

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#1
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Hello :-)

I have one application the need to be a kind of touch sensing but needs to work perfectly with water running on touch area.

mTouch from Microchip seems to work in my application, however, that pages states:

Microchip’s mTouch™ Sensing Solution provides a free and easy method for designers to add touch sensing to applications utilizing PIC® microcontrollers without the cost of fee-based licensing and royalty agreements. Being a source-code solution further helps engineers quickly integrate touch sensing functionality with their existing application code in a single, standard microcontroller, thus reducing the total system cost associated with current solutions.

Does I really need to use Microchip MCU to use that sensing technical idea? Does anyone implemented it with AVR?

I already investigated Atmel Qprox touch sensing technology dedicated IC but them may give problems detecting water.

I work in a small company in Portugal, coding C for AVR. I love AVR because of available Free Software tools like the GCC-AVR and AVR-Libc and support for GNU/Linux. I don't like Microchip because of inverse situation.
We would prefer to use AVR because we have hardware programmers and debuggers for them, also build tools, and not for Microchip MCU.

Thank you.

JPCasainho,
www.Casainho.net
.Portugal

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The technique should work with an AVR with similar hardware.

Microchip has free software, including gcc and other compilers.

Leon

Leon Heller G1HSM

Last Edited: Mon. Nov 24, 2008 - 12:05 PM
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If you download application note AN1202B from Microchip, you will see that you need the output of the analog-comperator on an i/o-pin of the controller. As far as I know, only the XMEGA-family of AVR has this feature.

/Martin.

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leon_heller wrote:
Microchip has (...) gcc.

Leon


Really? Cool, I must have missed that. Which families are supported, and where can I find out more?

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The C30 (dsPIC and PIC24) and C32 (PIC32) compilers are based on gcc. There are free versions of both, as well as Microchip's own C18 (PIC18F) compiler. See the Microchip web site.

Leon

Leon Heller G1HSM

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casainho wrote:
Hello :-)

I have one application the need to be a kind of touch sensing but needs to work perfectly with water running on touch area.

Hi JP,

Which AVR were you looking at using? And what kind of time frame for your application?

Eric

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leon_heller wrote:
The C30 (dsPIC and PIC24) and C32 (PIC32) compilers are based on gcc. There are free versions of both, as well as Microchip's own C18 (PIC18F) compiler. See the Microchip web site.

Leon


[OT]
Ah, I assume the PIC32 compiler is probably a customized version of GCC's existing MIPS compiler - so I guess I shouldn't be at all surprised that it exists.

I wasn't aware of the heritage of its PIC24/dsPIC compiler though.

As this is not contributing to the OP's original question, I'll shut up about it now.
[/OT]

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Quote:
mTouch from Microchip seems to work
Qtouch from Atmel DOES work...well it used to be Qprox :-) have been using their chips for a few years and without any software.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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mTouch can be one of two technologies. Both of which can be easily done on an AVR. With the first, capacitive, you don't have any restrictions on use. The other, inductive, will need to be licensed as it is a patented technique, for which Microchip seems to have some exclusivity. You can use a PIC, and do it for free, or you can find the company in the UK which holds the patents, and license the technology and use whatever micro you wish.

Note, the comments above about the comparator output apply to the Microchip example implementation of capacitive sensing. Q-Touch [now owned by Atmel] does capacitive sensing using an AVR at the core.

For Inductive sensing you only need an ADC and some GPIO's, the rest is external hardware... even on a PIC.

Given that you mentioned that you need the sensor to work with water running over it, I'm guessing you are referring to inductive sensing... in which case you are restricted to using a PIC, or taking out a license with the patent holder.

The above all assumes a commercial application. If this is for personal/hobby use, then you can do it on any micro without restriction. Patents only apply to the commercial application of a technology.

Writing code is like having sex.... make one little mistake, and you're supporting it for life.

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I am agree with Glitch about inductive sensing for water but at Microchip has patent I am not sure at it is so strong. this princip is very hold "inductiv sensor" use samme principe.
must find more info about what is in the patent.
Thierry

Thierry Pottier

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John,

Quote:
Qtouch from Atmel DOES work...well it used to be Qprox Smile have been using their chips for a few years and without any software.

No software?

Oh, I just made a pcb with a qt1106. Arrgh, horrible qfn to solder. Now I need to make some software. Do you have any tips I should be aware off?

Nick

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I have used the QT150 and QT160...I get other people to put them in. :wink:

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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Thank you all :-) - for some reason I didn't get e-mail notification so I didn't saw this answers before...

Well, we bought the development test board with the chip QT240 (capacitive sensing), after some tests was proven that it do not work well in our application when there is running water on it. Although we may use that IC on other projects ;-)

QT240 can work for 4 touch sensing buttons and have 4 simple digital I/O to indicate the state of each button.

TPE wrote:
I am agree with Glitch about inductive sensing for water but at Microchip has patent I am not sure at it is so strong. this princip is very hold "inductiv sensor" use samme principe.
must find more info about what is in the patent.
Thierry

I think the same... is a very simple principle... shouldn't be patented.

JPCasainho,
www.Casainho.net
.Portugal