Spin Code for Flexiforce Sensor

Comments

• JonnyMac Posts: 9,506

  2014-11-15 10:03 edited 2014-11-15 10:03

  This should do the trick -- I use this for reading a similar RC circuit in a commercial product. You will probably want to filter the result.
  

  pub read_pot(p)
  
  '' Reads RC circuit on pin p
  
    ctra := (%01000 << 26) | p                                    ' ctra in pos detect mode 
    frqa := 1
  
    outa[p] := 1                                                  ' charge cap
    dira[p] := 1
    waitcnt(cnt + (clkfreq / 500))                                ' wait 2ms
  
    phsa := 0                                                     ' clear counter
    dira[p] := 0                                                  ' allow discharge
    repeat
    while (ina[p])
    ctra := 0                                                     ' disable ctra
    
    return phsa
  
• GordonMcComb Posts: 3,366

  2014-11-15 18:45 edited 2014-11-15 18:45

  My version specifically tested with the Flexiforce. It is essentially the same as Jon's in function but uses the RCTime liberry.
  

  OBJ
  
  
    pst        : "FullDuplexSerial"  
    rc         : "RCTime"
  
  
  CON
     
    _clkmode = xtal1 + pll16x 
    _xinfreq = 5_000_000
           
  PUB Go | Sense 
  
  
    pst.start(31, 30, 0, 115200)
  
  
    repeat
      rc.rctime(0, 1, @Sense)           ' Flexiforce to pin 0, read rc
      pst.Str(String("Value: "))
      pst.dec(Sense / 100)              ' Display rc time decay in Sense var
      pst.tx(13)
      waitcnt(clkfreq / 2 + cnt)        ' 1/2 second delay
  

  
  Do you have a Propeller board with an ADC input? If so, you can use the Flexiforce as you would any variable resistor for ADC. For PropC, you could use any of the examples Andy has done that use the ADC inputs of the PAB or PropBOE. Go through the Learn examples -- the latest are on learn.parallax.com.