Velostat Stepsensor Problems...

[masterdot]

Hi there,
I want to build the Firewalker shoes from here.
I have problems to get a working velostat...

Meanwhile I bought three sheets of velostat, optimised my stuff for building and programming. But still it's not working.

I want to build the Firewalker with the Gemma Boards. I did get the debugging running and did even try with the power from the three AA instead of the power provided by USB via debug cable.
I tried to attach the wire chaos mode, in labyrinth style and the last try was as a spiral.
What I did was:
Taping the wires on each side of the velostat and trying to make sure they cross.
I did use Tesa tape and parcel tape. I did work quite precise to avoid errers and saw a video where someone made the sensor by quickly putting together.
I don't get what I do wrong... Meanwhile it would have been cheaper to buy a real step sensor for around 10 € each...

Would be great if someone could help... I'm at my end of ideas... Thanks in advance...

[adafruit_support_bill]

What do you see in the serial monitor when you test the sensor using the test circuit and code? https://learn.adafruit.com/firewalker-l ... st-circuit

[masterdot]

I see values around 15-20... But they seem not to relate to pressure. In the description they said it are values in the hundreds...

[adafruit_support_bill]

Please post some photos of your sensors. If you have a multimeter, measure the resistance between the two wires.

[masterdot]

threema-20190311-103430-4d27578e2ec044a1.jpg (419.94 KiB) Viewed 206 times

threema-20190311-103229-ce9794c59f8cb994.jpg (447.04 KiB) Viewed 206 times

threema-20190311-103430-4d27578e2ec044a1.jpg (419.94 KiB) Viewed 206 times

And I own a multimeter, but don't know how to use it :) I'm quite new to this and had Noone to show me :)
Hope the pictures help..

[adafruit_support_bill]

We can't see from the photo. Have you stripped the insulation from the wires under the tape?


We have a tutorial on multimeter use here: https://learn.adafruit.com/multimeters/overview

[masterdot]

Yes, the wire is blank.
So it should work from what you see, right? I’ll check out the multimeter., thanks for the link. I have a lot of experience with programming, but this low level hardware thingy is new to me. :)

[adafruit_support_bill]

Those look OK then. But please confirm the resistance readings with your multimeter. Also please post a photo showing your connections from the sensor to the processor.

[masterdot]

I currently have it with the Gemma as debug with alligator clamps. The only things soldered on it is the battery case.
Multimeter takes some time, have to find it again :) what should I get weth the multimeter as values?

[adafruit_support_bill]

Please post a photo showing all of your connections whether soldered or not.

The response of DIY sensors will vary considerably from one sensor to the next. But with no pressure on the sensor, the resistance should be quite high. And the resistance should drop when you put pressure on it.

[masterdot]

Hey there,
Quick response: I found the multimeter, watched your tutorial and tested it...
With nothing on it it shows low values, with pressure it shows higher values...
I should get lower when pressure, higher without. So it seems to work the wrong way?

I think I take some time and make a video of everything, seems to be a good idea?!
Don't know what I'm doing wrong...

[adafruit_support_bill]

I should get lower when pressure, higher without. So it seems to work the wrong way?

That depends on how you have it connected and what you are measuring. If you are measuring resistance, it should get lower with pressure. If you have it connected in a test circuit, and are measuring voltage, the voltage will increase with pressure.