piezo pressure sensor to PIC

Discussion in 'The Projects Forum' started by kutalinelucas, Jul 23, 2011.

  1. kutalinelucas

    Thread Starter Active Member

    Nov 20, 2007
    Hey guys, i was wondering if i could get some advice...

    I'm looking to get a high logic level on a PIC18f and a basic stamp 2 IC pin when a moderate amount of pressure is excerted on a piezo film transducer from rs:


    The problem is my project is complex enough for me and I don't really have the time to implement an ADC and measure voltage relative to pressure, so I was wondering if i could attach the live terminal of the piezo disk to one input of each IC, and put 2 opposing diodes running to earth in between the piezo and the IC's (whlie grounding the ground of the disk)

    I sorry if this isn't too clear, but im having difficulty posting my image...i'm new to forums

    if you would like any more details of my project, or if there's anything else I could help you with then give me a shout.

    any suggestions would be brilliant

  2. nsaspook

    AAC Fanatic!

    Aug 27, 2009
  3. kutalinelucas

    Thread Starter Active Member

    Nov 20, 2007
    i'm building a robotic hand for my masters robotics dissertation. I'm quite happy with the control side of my project, I have a dextrous solution with high grasping touque, where every other robotic hand either has one or the other. The probelm is I've used stepper motors for the bottom knuckles, and planitary geared motors using twised actuated motors for the upper two knuckles (underactuated with a rack-and-pinion for the two)...but I need some feedback if the steppers stall. The problem is no matter how cool the control system is, it will loose all credability if it looks a bit silly...which a 9 tactile switchs would. At least a piezo film pad would sit flush to the fingers, which has taken allot of time to make it as anthropomorphic-looking as possible. Theoretically the piezo circuit it should work (i think anyway)...but my analog electronics isn't my forte, so I was hoping somebody who knows a bit more could help me with the piezo film way
  4. SgtWookie


    Jul 17, 2007
    I'm afraid you're not going to get an output from it, really.
    What the transducer needs is a square wave input @ 4200Hz in order to emit sound waves. It's kind of a piezo buzzer without the associated electronics present.

    There is no mention of an electrical output from the device; only electrical input and resonant frequency.

    Perhaps you can detect the excess pressure by using a somewhat flexible or spring-loaded rotating mount for the steppers, and sensing if the mount flexes/rotates too much?
  5. Kermit2

    AAC Fanatic!

    Feb 5, 2010
  6. kutalinelucas

    Thread Starter Active Member

    Nov 20, 2007
    thanks for getting back to me...guess I have a bit more reading to do. I've found similar sensors like the sparkfun product in the UK for £5, so i'll order them this evening and see what happens...

    thanks again