QTI sensor

Robot Freak

Are there any QTI sensor examples/objects around here?
I can't find one...

Kind regards,
Robot Freak

Perry

There is a complete propeller sumobot somewhere on Parallax's site, can't find it now though.
here is the qti code

' main line code

VAR
 
  long qti                                   ' Stores Qtis object results

OBJ

 qtis      : "Qtis" 

PUB main

 qtis.start(16, 17,@qti ) 

    case qti
      %00, %01, %10: bot.go(bot#BACKWARD)
                     waitcnt(clkfreq/2 + cnt)
    case qti
      %00, %01:      bot.go(bot#ROTATE_RIGHT)
      %10:           bot.go(bot#ROTATE_LEFT)
    case qti
      %00, %01, %10: waitcnt(clkfreq*2/3 + cnt)    

' and the qti module

{{File: Qtis.spin

Demonstrates a way of reading QTI sensors repeatedly in a separate cog and
updating a variable in the parent cog during each update.

}}

var

  ' Order matters for declarations of sPin, ePin, and address
  ' because of longmove in start method.
  long sPin, ePin, address, qtiBits  
  long stack[noparse][[/noparse]30], cog

pub start(_sPin, _ePin, _address) : okay

  {{ Starts the servos cog.
     _sPin and _ePin are the endpoints of the contiguous group of QTI signal pins.
     _address is the address of the variable that receives the QTI bit values.
     Returns t/f for success.
  }}
  
  longmove(@sPin, @_sPin, 3)
  okay := cog := cognew(qtis, @stack) + 1
  if okay
    okay := @qtiBits

pub stop

  '' Stop servos object and free the cog

  if cog
    cogstop(cog~ - 1)

pri qtis

{{This method repeatedly measures the surface monitored by one or more QTI sensors
and stores the result in the parent object's variable (determined by _address in
the start method).}} 

  outa[noparse][[/noparse]ePin..sPin]~~

  repeat

    dira[noparse][[/noparse]sPin..ePin]~~
    waitcnt(clkfreq/2000 + cnt)
    dira[noparse][[/noparse]sPin..ePin]~
    waitcnt(clkfreq/2000 + cnt)
    qtiBits := ina[noparse][[/noparse]sPin..ePin]
    long[noparse][[/noparse]address] := qtiBits
    

Perry

Robot Freak

I'll give it a try and post the results.

Thanks a lot!

Robot Freak

Eh... until now, I used 3.3V to power the QTI sensor.
Is this fine, or do I have to use 5V with a resistor on the white pin?

Paul Baker

The 470Ω bias resistor is for a 5V design, so you should be supplying it with 5V to ensure proper operation. You may also want to put an additional 470Ω resistor on the red line to protect the Propeller pin.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.