RPM/MPH help please

Capdiamont

I'm using the Melexis 90217 Hall-Effect Sensor, with the prop. I'm using the motor minder code. I've hooked it up per motor minder pin 7, and per the milling rpm basic stamp page. I've tried running pin1 of the sensor to 5v+ or the 3.3v+. I wasn't sure if the sensor's pin3 to pin7 of the prop should go through a resistor or not with using the 5v supply with the sensor. I'm running off a fresh 6v lantern battery. The capacitor is is the ceramic disk type 0.01uf. I did read earlier that someone was able to use it on 3.3v even though it like 3.5v, and increased the capacitor.

The problem I'm having is it showing rpms when it should be zero. I just swing the magnet when necessary to test.



Please see my last post for lastest code

Post Edited (Capdiamont) : 9/21/2009 12:11:33 AM GMT

RS_Jim

I know this is not of much help but I experienced the same problem with the hall effect sensor and the SX. Had to return to an optical TAC.
rs_jim

Capdiamont

hopefully the code is attached. I have viewport running. I've bypassed the sensor circuit, instead have 3.3v through a resistor to pin 7 of the prop. Note I have viewport objects/code installed. The problem is, although I have pin 7 in viewport showing steady as a rock, my Frpm won't go to zero, but will change by changing pin 7 state. revCount stays at 6424.

Capdiamont

My MPH variable is ended up in the thousands, yet by watching the input, it doesn't bounce. Can somebody please check the code to see if it is good? I've completely restarted from scratch. I'm slowly learning the prop. How long can the sensor be away from the prop/supporting cap/resistor circuit?

{{

  header
      
      
}}
      

CON

  _CLKMODE = XTAL1 + PLL16X        ' 80 Mhz clock
  _XINFREQ = 5_000_000

  RPSPin   =  7                ' shaft encoder - Propeller pin

  ' F1 = 1.0                          ' floating point 1
  ' F60000 = 60_000.0                 ' floating point 60,000
  Diameter = 10.0                       ' diameter of wheel in inches
  Circumference = Diameter * PI        'result in inches

OBJ

  num   : "simple_numbers"
  F     : "FloatMath"
  FS    : "FloatString"
  vp    : "Conduit"

VAR

  long  RPS , RPM             ' rev per second, and minute indexes
  long  MPH, Odometer                 ' 
  long  IO                           ' to share io pin info
  byte  RPMArray[noparse][[/noparse]60] , RPMI , RPMI_B ', MPH
  
PUB Init

  ctrb[noparse][[/noparse]30..26] := %01010 'ctrb module to POSEDGE detector
  ctrb[noparse][[/noparse]8..0] := RPSPin    'count revelutions per second
  frqb := 1 'Add 1 for each cycle
  vp.share(@RPS,@RPMI_B) 'allow sharing of first to last varable to viewpoint for debuging uses addresses of varables
  Odometer~
    
    
     repeat
       
       IO:=INA
       phsb~
       waitcnt(clkfreq + cnt)
       RPS := (phsb)
       Odometer += RPS
       RPMArray[noparse][[/noparse]RPMI++] :=  RPS    'store RPseconds in a different place each second
       If RPMI =>= 60
         RPMI~    '60 is above range of array, so reset to zero
       RPM~                        'zero out rpm before adding together array
       repeat RPMI_B from 0 to 59  add up all the revs that happned in the minute
         RPM += RPMArray[noparse][[/noparse]RPMI_B]
       MPH := Circumference * RPM 'calcuate MP
       MPH *= 60   'make it hour time
       MPH /= 63360   'convert to mile from inches
    

Post Edited (Capdiamont) : 9/21/2009 12:13:44 AM GMT

Capdiamont

I think I messed up by not accounting for floating point math.

I changed some of the code, hopefully it works, will have to test in the morning.

       MPH := f.FMul(Circumference, FFloat(RPM))'calcuate MP
       MPH := f.FMul(MPH, 60.0)   'make it hour time
       MPH := f.fDiv(MPH, 63360.0)   'convert to milePH from inchesPH