Function Confusion

Comments

• Mark_T Posts: 1,981

  2013-10-07 13:37 edited 2013-10-07 13:37

  ajward wrote: »

  Hi All...
  
  I know there's probably a simple answer, but I'll be darned if I can find it!
  
  After getting my tracked vehicle running with the Stingray demo code, I've started using Kye's "PWM2C_HBDEngine" from the OBEX for more control. My code (See below) has functions to ramp up, ramp down and run forward and pivot turn to the right. Running the first three functions on the MSR1 board, Ted ramps up, runs forward for a bit, ramps down and stops. However, when I add the fourth function "pivot_rt", he ramps up runs forward, ramps down, but the vehicle never stops pivoting. What am I missing here?
  
  Any wisdom appreciated!!!

  
  I suspect you aren't allowed a negative rightDuty value?
• ratronic Posts: 1,451

  2013-10-07 14:39 edited 2013-10-07 14:39

  Amanda after your pivot_rt method you should probably run your ramp_dn method to stop. Also you only need to run the engine start instructions once in the beginning of your code. The methods automatically return so you do not
  
  need to write return in each one unless there is a variable you would like to return.
• ajward Posts: 1,130

  2013-10-07 15:16 edited 2013-10-07 15:16

  Mark_T wrote: »

  I suspect you aren't allowed a negative rightDuty value?

  
  Thanks for your reply Mark!
  Yeah... I guess that has to be it. I've used that obex module before and I could swear I've sent negative values to the function before. Of course, I can't find my previous code to verify. <grumble>
  
  Anyhow... thanks again!!!!
  
  Amanda
• ajward Posts: 1,130

  2013-10-12 14:48 edited 2013-10-12 14:48

  @Dave - Thanks for that. Working on the little beastie right now. I'll give your ideas a try!!!
  
  Amanda
• Duane Degn Posts: 10,588

  2013-10-12 15:03 edited 2013-10-12 15:03

  ajward wrote: »

  I could swear I've sent negative values to the function before.

  
  I'm pretty sure you're right about negative values being valid. I think negative values put the motor in reverse.
  
  It would be easier if you attached the code as an archive and then we could also see the child object.
• ratronic Posts: 1,451

  2013-10-12 15:22 edited 2013-10-12 15:22

  In the object she is using the values for leftduty and rightduty go from -1000 to 1000 to go either way.
  
  Edit: Duane is right you have to put a negative # to go one way and a positive # to go the other with 0 being stop.
• ratronic Posts: 1,451

  2013-10-12 17:55 edited 2013-10-12 17:55

  After looking again at your pivot_rt and ramp_dn methods your ramp_dn method first puts the wheels at full speed before ramping down. So you might not want to put ramp_dn after pivot_rt. You can stop the wheels by -

  hbd.leftduty(0)
  hbd.rightduty(0)
  
• ratronic Posts: 1,451

  2013-10-15 16:09 edited 2013-10-15 16:09

  I had never used Kye's object before so I tried this example on my Stingray and it works. It also shows another use of return to escape a repeat loop. Maybe you can get some use from it.

  Con                                                         
                                                           
    _CLKMODE = XTAL1 + PLL16X                              
    _XINFREQ = 5_000_000
     _leftFW = 24   
     _leftBW = 25   
     _rightFW = 26  
     _rightBW = 27
      
     '_timeStepInMilliseconds = 10     
     _updateFrequencyInHertz = 8_000
      
     RAMPING = 5  '*100us delay per step duty cycle
     
  Var
    long left_old, right_old
    
  Obj
    
    hbd : "pwm2c_hbdengine"
    
  Pub Main
    
    hbd.hbdenginestart(_leftFW, _leftBW, _rightFW, _rightBW, _updateFrequencyInHertz)  'start pwm
      '
    Wheels(-500, 500)    'forward @ half speed
    
    waitcnt(clkfreq+cnt) 'pause before setting wheels again
        
    Wheels(500, -500)    'reverse @ half speed
    waitcnt(clkfreq+cnt) 'pause before setting wheels again  
    Wheels(500, 500)     'turn left @ half speed
    waitcnt(clkfreq+cnt) 'pause before setting wheels again
    Wheels(-500, -500)   'turn right @ half speed
    waitcnt(clkfreq+cnt) 'pause before setting wheels again
    Wheels(0, 0)         'stop
    
  Pub Wheels(left, right) 
     
    repeat
    
      if left < left_old                       'increment or decrement by one to new speed'
        hbd.leftduty(--left_old)
        
      if left > left_old
        hbd.leftduty(++left_old)
        
      if right < right_old  
        hbd.rightduty(--right_old)
        
      if right > right_old
        hbd.rightduty(++right_old)
         
      if left_old == left                      'check if both left and right wheels-
        if right_old == right                  '-are @ new speeds and return from-
          left_old := left                     '-this method when met
          right_old := right       
          return
    
      waitcnt(clkfreq / 10000 * RAMPING + cnt) 'RAMPING * 100us pause per step duty cycle
  

  zip

  zip

  Stingray.zip

  3K

  Stingray.zip 3.4K