Force sensitive resistor?

L

LGP

New Member
Hello everyone,
I need some assistance with a project. I have an 08m2 and would like to connect a force sensitive resistor to it. It will output force applied to an LED graph bar. I've searched the forum and read the manuals but can't find anything on it. Still new to picaxe and this is my second project. I google searched but all I seem to find is arduino stuff.

I'm also looking for some example codes. Just need some guidance to follow.

Thank you.
 
A

alband

Senior Member
Something like this presumably: http://www.coolcomponents.co.uk/catalog/force-sensitive-resistor-inch-p-718.html?gclid=CN6imcefsrYCFcHHtAodu3QAOA

We do need to know what force sensitive resistor you've got though, LGP, if you've got one at all yet. If you have a link to a datasheet or at least a web page, that would help a lot. Do you have any of the other stuff yet (e.g. the bar graph) or is it all theoretical for the moment?

Page 79 of manual 1 show how you'd read a light sensitive resistor which is likely to be the same as a force sensitive resistor for the program and circuitry.

Take a look at the readadc command. You'll also probably need a bar graph driver chip. Since the 08M2 has limited pins and a sensible bar graph will have at least 8 segments, you're likely to need to have a chip inbetween the PICAXE and the bar graph. If you haven't already got the 08M2, it might be easier getting a slightly bigger chip with more outputs.
 
L

LGP

New Member
Thanks everyone for responding. Here is the link to what it is: https://www.sparkfun.com/products/9673

FSR.jpg

This is what I'm trying to make, a device for teaching CPR (Cardiopulmonary Resuscitation). When performing chest compression's, the person administering aid has to push down on the chest 2" or greater. Often times, students don't push hard enough. As a training aid, I would like to embed the force sensitive sensor into a pad or other material to be placed in the area where the chest will be compressed. As force is applied, data is sent to an 08M2, the picaxe will then output the information to an LED bar graph, like the one pictured below.

LED Bar Graph.jpg

This would give feed back to both student and instructor. If the student is pushing down on the chest at an adequate depth, the LED's will light up all the way to green. If force is inadequate, red LED's will light up. Yellow LED's show moderate force.

Again, thank you for the responses. I will review the links provided.
 
L

LGP

New Member
alband said:
Something like this presumably: http://www.coolcomponents.co.uk/catalog/force-sensitive-resistor-inch-p-718.html?gclid=CN6imcefsrYCFcHHtAodu3QAOA

We do need to know what force sensitive resistor you've got though, LGP, if you've got one at all yet. If you have a link to a datasheet or at least a web page, that would help a lot. Do you have any of the other stuff yet (e.g. the bar graph) or is it all theoretical for the moment?

Page 79 of manual 1 show how you'd read a light sensitive resistor which is likely to be the same as a force sensitive resistor for the program and circuitry.

Take a look at the readadc command. You'll also probably need a bar graph driver chip. Since the 08M2 has limited pins and a sensible bar graph will have at least 8 segments, you're likely to need to have a chip inbetween the PICAXE and the bar graph. If you haven't already got the 08M2, it might be easier getting a slightly bigger chip with more outputs.
Click to expand...
Thanks Alband.

I have the 08M2. The FSR and bar graph is on order, just waiting for it to come in. Looks like I will have to get a bigger chip, which one would you recommend?

I'll look at page 71. Seems like the same concept.

Thanks again.
 
Hemi345

Hemi345

Senior Member
I wonder if something like this flex sensor:

https://www.sparkfun.com/products/10264

would be better suited to your application? I'm trying to figure out how you will measure the chest needing to compress 2" with the FSR unless there is something built into Resusi Annie that will make it easy to use.
 
S

SteveT

Senior Member
Every Resusi Annie I've ever trained with had this sort of setup inside it. DSC05642.jpg531965564_tp.jpg
From what I remember the central disk activated something akin to an old fashioned petrol tank sender unit (basically just a geared pot). Also from what I remember, every Resusi Annie I've ever used all had the basic circuitry inside, only the cheaper models didn't come with a display to make use of it.
 
P

PaulRB

Senior Member
Lgp,

A 14M2 would only have just enough pins, so maybe go 18m2 or 20m2 which is slightly cheaper anyway.

Alternatively, use your 08m2 but use a driver chip for the display. A 4017 decade counter might do.

Paul
 
S

SAborn

Senior Member
I think this is a wonderful project for a picaxe, and perhaps the most inavated use of a picaxe that can help many.
Im guessing there is a lot of budget Annies out there and a simple add on circuit for a Annie upgrade would allow a few low budget operations to upgrade with the help of a forum member, and there is 1000's of them.

Most of us in life do a Resusi Annie at some point in life, and it would be great to see other forum members donating their skills to follow in your footsteps.

Be sure to post your final project details to the forum under a good title, so others can easily find it in a web search.

SteveT seems to have the guts of Annie well understood, so might be worth investergating further what is currently installed in budget Annie..
 
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