Touch sensor failes

[Geerinckx]

Hi!

I have a problem with the touch sensor:

When i don't connect the ltc module to the pc and i dont touch sensor, the inputs stays at 127 en when i touch it goes 0,127,0,127,0,127......

When i connect the Ltc module to the pc the input stays 127 also when i touch it!

I also tried to connect Vs to the ground of a power socket, en connect Vs to my skin but nothing helps!

Do you have sugestions to solve this problem?

X-Mass Grtzz

Gert

[SLP]

Often those sensors have a different pinning as usual pots.

Be sure to have the sensor connected right.

[Geerinckx]

Thx for the fast reply

But there isn't a pot! i use just a wire with at the end a coper plate!

grttzz

Gert

[doc]

This is really a strange behaviour.

I need a little more information:

For what purpose do you use the LTC module?

Just as a Monitor or do you use also the serial port?

When the LTC is plugged in: What is the behaviour of the other controls ( knobs, pots ...). Is a normal knob changing its value by pressing it or not?

greets

Doc

[Geerinckx]

Hi Doc

The LTC modules is for connection to the Pc with the rs232 port!

The behavior of the other stuf is normal! pot's all work buttons to!

But i was thinking, for the testing purpose i only stuffed 1 * 74hc165

of thad DIN, the other DIN (MIDIBOX 64) is fully stufed

I connected the serial input to the serial output with a wire! of the not stuffed 74hc165 but it is in the end of the row:

______              _______________              ____________________________

| Core | -------> | DIN full stuffed | -------> |DIN first 74hc165 stuffed others|

--------            ------------------            | Connected true with a wire!    |

                                                              --------------------------------

Is thad maybe the problem?

X-mass greetings To all midi-boxers

Gert

[SLP]

Often those sensors have a different pinning as usual pots.

I meant "compared to usual pots"

so you want your touch sensor to act like a analog controller...

But it this case you have to connect it to the AIN , not to the DIN

[Geerinckx]

Hi SLP

No i just wonne have a DIN to trigger some buttons on my pc!

i'm a light jocky in a club and i wonna replace the old controller to a pc based controller! but without a hardware solution it is not possible!

So i use the touch sensors for really quick flashes en shutters for the pars, strobe

scans, & movingheads!

Grtzz

Gert

[audiocommander]

- if you have built an active LTC module, I expect you removed the optocoupler from the Core?

- does it work if you leave out the full stuffed DINx4 board and connect only the board your touch-sensor is connected to?

regards,

Michael

[Geerinckx]

Hi audiocommander

Nope nothing changes! stil 0,127,0,127.....

en when i connect myself to the 0V it stays at 127

Grtzz

Gert

ps: I connected the input of the other 3 schift registers with a wire to the output

      Is this correct? or should it be resistors?

[audiocommander]

en when i connect myself to the 0V it stays at 127

hmm... I don't understand that part ;D

I thought it works if the LTC is not connected (0 + 127): For a button, this would be the expected behaviour. Now when you connect the LTC you only get 127, is that right?

That means the error should be at the LTC or the DIN-module or the optocoupler.

I connected the input of the other 3 schift registers with a wire to the output. Is this correct?

The DINx4 modules have to be chained. That means: Core J9 --> J1 DIN#1 J2 --> J1 DIN#2

What I meant was to leave out the first DINx4 module to see if the error is located at the second DIN.

Can you make a photo and attach it?

In the meanwhile you could go through all the wirings and check them against the plans available @ uCApps.de; I think it sounds like a wiring issue...

best regards,

Michael

[Geerinckx]

ltc not connected:

when i dont do a thing it stays at 127

When i touch it is changes from 0,127,0,127...........

When i clamp myself to the 0V it stays at 127

When i connect the ltc:

dont' touch it stays 127

when i touch it, it also stays at 127

also with skin connected to 0V it stays 127

Jah i knew what you mentiont

But everything else works! alls DIN's & AIN's

so i disconected the stuffed module en connected only the module with 1 74hc165

but nothing is different

i don't use an optocoupler becaus i use an LTC module

Grtzz

Gert

[audiocommander]

Okay, we're getting at it, I think everything is working fine:

What exactly are you using as "Touch Sensor"?

[Geerinckx]

just a wire with a plug un the end

just for testing

Does it make anny difference?

[audiocommander]

This will not work. And if it works, I'd be astonished.

You need a capacity based touch sensor circuit (search for "Quantum QProx QT113") or if you want to stay connected while touching: a skin resistance circuit. Last one is probably the easiest:

If you measure your skin resistance with a multimeter, you'll find out, that your skin as about 1 M to 20 M. If you look here: http://www.midibox.org/dokuwiki/doku.php?id=sensors  and  http://www.midibox.org/forum/index.php?topic=6506.0 you should be able to connect a basic skin restisance sensor. The topic was meant to be used on a AIN, but it's so easy, I think you'll be able to adapt it for a digital ON/OFF signal...

However, I'd use a capacity based circuit, because you don't need to be wired. Just google around a bit and you should find plenty of touch circuits for switches!

:)

cheers,

Michael

[Geerinckx]

i already tryed the QT160 i have him here with me but it works to slow and i cant touch 2 pats at the same time

in this aticle http://www.midibox.org/forum/index.php?topic=4136.0

it saise it would work with just cheap etched board!

Grtzz

Gert

[audiocommander]

so you connected it exactly like described here: http://www.ucapps.de/mbhp/mbhp_din_touchsensors.pdf ?

And what kind of application are you using (eg MB64(e) ?)

Does anyone know if J14 functionality is supported in all apps?

Best regards,

Michael

[Geerinckx]

Yes exactly the same!

I only connected 2 sensors the others to the ground of thad 74hc165

Or is thad maybe a mistake??

I'm using MB64

I pretty sure J14 is supported

when i disconect J14 is gives all random information...........

Greeting

Gert

ps: thx for your time en help

[Geerinckx]

I get crazy from it!

Strange thad it works whith the other fellows but not with me!

I don't have to modify the code in the pic, am i correct?

Grtzz

Gert

[audiocommander]

Strange thad it works whith the other fellows but not with me!

Well, as you can read on the second page of the topic you are referring to, similar problems like yours occured. I bet it behaves exactly the same if JazzyPidjay would connect an LTC module!

So I think it's rather a basic construction error:

1- the first problem i have encountered is when i touch a sensor the message 0,127,0,127,0,127... was send in loop to resolve this problem i have simply connect the 0v of the midibox to the ground.

2- ok at this stade, when i touch a sensor it send correctly the values like a button. (but very quickly and intuitively) but when i touch to or more sensors, there's no more message send or messages are send randomely.

to fix this problem, i simply plug myself with a jack in the belt directly to my skin connected to the ground

Now my body was perfectly at 0v, the computer & the midibox also !! and i can touch 32 or more sensors, without any problem, like a button.

i search a better way to solve this problem, but for now i plug (myself) & play  ;D

This all sounds like grounding/shielding issues. Normally the touch sensing pin J14 is used for motorfaders (see "Touch Sensors" on the MBHP MF page: http://www.ucapps.de/mbhp_mf.html ; there's also a very detailed explanation by TK here: http://www.midibox.org/forum/index.php?topic=1544.0 ). You don't need to ground yourself to get that working! So either the MB64 application is not configured to use that kind of feature (don't know that, 'cause I go no MB64) or there is a basic mistake about your implementation of the touchDetection.

Why don't you use a normal button switch to test if your basic equipment is working; then you could resume experimenting with different touch detection circuits! J14 is not the only possibility to get that kind of feature...

Best regards,

Michael

[doc]

I'm also unsure if J14 is supported for touchsensors in other applications than the LC.

With Midibox LC it is definitly working (for the touchsensors of the motorfaders). But I also have to connect myself to ground before I touch a fader.

You changed the resistors correctly for the Touchsensor-DIN (no 10k resistors there?).

Another thing:

J14 (RD4 on the PIC) sits directly beneath the RX Pin. Have you checked these connections? Is there perhaps a short or something else between J14 and RX/TX. This would be the only "harware" explenation for the LTC / Touch behavoiur.

greets

Doc

[audiocommander]

I just experimented with a QT113 and found that it's a great chip to use touchDetection: I don't know why you experienced a slow response with the QT160 AFAICS it's the same as the QT113 but just multichannel (QT113: http://de.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=9775749 ). I checked it with an LED and cannot determine any slow behaviour... maybe you got the wrong Cap-Values?

Best regards,

Michael

[Geerinckx]

Hi guy's

Thx for all the reply's

i did experimented with the QT160! but i cant touch 2 buttons at the same time!

and the respons time is to slow! maybe a 20MHz istead of a 10MHz will do the trick! I used 33µF capps for the inputs but i think de cap doesn't affects the speed of it it just changes the sensetivity! correct me if i'm wrong :-X ??? ;D

I tested everything with buttons and everything works fine!

10K pull-ups are gone to!

I do think Touch Sensors are sepported in MB64 becaus you can adjust the sensetivity in the main asm file and in the sysex editor for the MB64

I will search for a bad grounding, but i think i gonna find nothing i tripple checked everything, but ones again doesn't harms annybody 8) ::)

Yes i think i gonne search for an other solution if this doesnt works

X-mass greeting

Gert

[audiocommander]

Hi Gert,

the respons time is to slow! maybe a 20MHz istead of a 10MHz will do the trick! I used 33µF capps for the inputs but i think de cap doesn't affects the speed of it it just changes the sensetivity! correct me if i'm wrong

the response times of the QT160 and the QT113 are different:

point 2.1.6. of the datasheet explains this for the QT160:

Response time is fixed at 99ms at a 10 MHz clock. 
Response time cna be altered by changing the clock frequency. 
Doubling the recommended clock frequency to 20 MHz will halve 
the response time to 49ms. Response time will become slower if 
the total duration of all bursts is greater than 33 ms, 
i.e. an average of 5.5 ms per channel[/code]

...and the burst duration is to set by a cap.

i did experimented with the QT160! but i cant touch 2 buttons at the same time!

hehe... this is a special feature of the QT160 that's called AKS - Adjacent Key Supression, that's described on the first page of the datasheet:

[code=QT160 Datasheet]The QT160 also offers the unique adjacent key
suppression (AKS) which suppresses touch from weaker respnding
keys and allows only a dominant key to detect, for example to
solve the problem of large fingers on tightly spaced keys.

So, that's the explanation, why only one input is working at a time!

hmm... :-\

maybe you should invest some money in some single operated QT113's. The setup of the QT113 seems quite easy, see:

The QT113's response time is highly dependent on 
burst length, which in turn is dependent on Cs and Cx. With 
increasing Cs, response time slows, while increasing levels of 
Cs reduce response time. Fig 4-3 shows the typical effects of 
Cs and Cx on response time.[/code]

Best regards,

Michael

[Geerinckx]

Ellows

I know, next time i buy such an expensive Ic i furst fully read all the specs!

What did you pay for the QT113

I payed 11€/IC so fot the 2: 22€

Grtzz

Gert

[SLP]

Why don't you just use tactile switches?