Pushing the Evelope

Comments

• Tracy Allen Posts: 6,667

  2013-08-24 18:08 edited 2013-08-24 18:08

  The trick is to make the RCTIME very fast by using a smaller value of capacitor. Then multiply the RCTIME by a scale factor to make it right for the Valve. You can use a different scale factor for each button/valve.
• alnajjar1 Posts: 110

  2013-08-24 20:42 edited 2013-08-24 20:42

  The problem is that I have up to 8 independent user pushing these buttons. It would be very easy if I only have one button pushed at a time.
• Beau Schwabe Posts: 6,572

  2013-08-24 20:59 edited 2013-08-24 20:59

  If you move the RCTIME to an external hardware function, say with a 555 or 1/6th of a 74HC14 and use the COUNT command instead of the RCTIME command, then the amount of time spent reading the POT would always be the same within your code, and somewhat predictable.
• Phil Pilgrim (PhiPi) Posts: 23,514

  2013-08-24 21:03 edited 2013-08-24 21:03

  I would dispense with the pot altogether and replace it with a "program" switch that's not accessible to the public. With the program switch on, pressing a button and holding it will cause the BS2 to count how many button-read and pump-write cycles the pump is suposed to stay on for that button. This value can be stored in the BS2's EEPROM for each button. With the program switch off, pressing a button or buttons will initiate the "on" cycle for the button(s) pressed, turning the pump(s) off after the prescribed number of read/write cycles.
  
  -Phil
• Unsoundcode Posts: 1,532

  2013-08-25 08:01 edited 2013-08-25 08:01

  Hi, it seems to me that the "getswitches" routine could be made more efficient.
  
  Whether a button is pressed or not pressed the "getswitches" will scan and then goto "sendout". So if no button has been pressed the Stamp is just going to be unresponsive for as long as 2 seconds until it comes back to scan the switches again. During that time it is possible it may miss the users input.
  
  Also the switches must be in a pressed state when "inload" receives its pulse, this means that if you had for example 5 users pressing buttons any small difference in time between when they pressed the buttons would give you an apparent error on the output, in other words you would read some but not all of the user inputs.
  
  I think it would be better if you verified there actually was user input before moving into the output routine. Something like the following might work, the first read checks for input and the second read gives time for everyone to press. The pause can be adjusted to whatever works best.
  

  getSwitches:
  
    newSW=0
  
    Do While newSW < 1
       PULSOUT inLoad, 5                               ' load switch inputs
       SHIFTIN inData, inClock, MSBPRE, [newSW]     ' shift them in
    Loop
  
       PAUSE 20                                     ' allow time for all users to press
       PULSOUT inLoad, 5                               ' load switch inputs
       SHIFTIN inData, inClock, MSBPRE, [newSW]     ' shift them in
  
  RETURN
  

  
  Jeff T.
• Sapphire Posts: 496

  2013-08-25 10:50 edited 2013-08-25 10:50

  Al,
  
  What time range do you want to have for the individual pump run times? Do you need to have these individual pump run times field programmable, or could they be fixed?
  
  If you maintain 8 separate timers for each pump, you could have different times for each of them and they could run simultaneously. Eliminating the re-reading of the POT will speed processing up, and if the pump run times don't change (or are only changed by you) then they can be done outside of the normal loop.
• alnajjar1 Posts: 110

  2013-08-25 11:08 edited 2013-08-25 11:08

  Brilliant! thanks Jeff. I will try this and report back. The challeng for me is how to turn individual valves without using the Pause command and tying up the BS2 from monitoring other switches. Your suggestion and what Phil suggested may get me closer to the desired goal.
  
  Al
• alnajjar1 Posts: 110

  2013-08-26 12:46 edited 2013-08-26 12:46

  The pot is only checked at start up and not as part of the main loop and therefore the run-times for individual pumps are meant to remain fixed unless the pot value is changed and the BS2 is reset. I am not sure how I can maintain 8 timers and make these timers consistent. Using the Pause command is out of the questions as it will stop the BS2 from checking the switches continuously. Could you craft a quick example of how to maintain the individual timer? I can setup 8 different counters counting the number of cycles the button has been in a certain state, but that will not give a consistent time.
  
  Thanks for your thought...
• Sapphire Posts: 496

  2013-08-26 14:05 edited 2013-08-26 14:05

  Al,
  
  What I'm suggesting is to setup 8 counters that all run in parallel, and only one pause to set the timing on them. I've added that to your original program. Take a look and see if it works for you.
  

  ' {$STAMP BS2}
  ' {$PBASIC 2.5}
  
  ' pin assignment
  outData       PIN          2             ' Data pin to 74HC595.
  outClock      PIN          0             ' Shift clock to '595.
  outLoad       PIN          1             ' Moves data from shift register to output latch.
  inData        PIN          7             ' shift clock (74HC165.2)
  inClock       PIN          9             ' serial data (74HC165.7)
  inLoad        PIN          8             ' input load (74HC165.1)
  LED           PIN          14            ' red indicator LED
  Pot           PIN          15            ' adjust water valve on-time
  
  ' variables
  onTime        VAR          Word          ' calibrated pot value in ms
                                           ' pot rane 0-6000.  max on time = 2000ms
  i             VAR          Byte          ' general counter
  oldSW         VAR          Byte          ' previous reading from the HC165
  newSW         VAR          Byte          ' current value of switches
  valves        VAR          Byte          ' binary represetatio of the output to the HC595
  switches      VAR          Byte          ' switches that just turned on
  counter       VAR          Byte(8)       ' counters for each switch
  
  DATA 10,20,30,40,50,60,70,80             ' valve run times in multiples of onTime
                                           ' onTime should be small, like 1/10 second
  
  Reset:
    HIGH inLoad
    GOSUB readPot
    FOR i = 1 TO 3
      HIGH LED : PAUSE onTime : LOW LED : PAUSE 500
    NEXT
    valves = 0 : GOSUB sendOut
    oldSW = 0 : newSW = 0
  
  monitor:
      GOSUB getSwitches                      ' get switch inputs
      DEBUG HOME, BIN8 newSW                 ' display current status
      switches = oldSW ^ newSW & newSW       ' new switch presses in switches
      oldSW = newSW                          ' update old value
      'DEBUG HOME, BIN8 ? oldSW, BIN8 ? newSW, BIN8 ? valves
      'valves = newSW : GOSUB sendOut
      GOSUB ticker                           ' check the counters
      GOSUB sendOut                          ' update valve status
      PAUSE onTime                           ' pause a short time (onTime should be small, try 100ms)
  GOTO monitor                               ' start over
  
  ticker:
    valves = 0                                 ' all valves off unless set by a timer
    FOR i = 0 TO 7                             ' eight timers
      IF 1<<i & switches THEN                  ' switch just pressed
        READ i,counter(i)                      ' loads a unique time for each counter, stored in EEPROM
      ENDIF
      IF counter(i) > 0 THEN                   ' counter not zero
        valves = 1<<i | valves                 ' turn on valve
        counter(i) = counter(i) - 1            ' decrement counter
      ENDIF
    NEXT
  RETURN
  
  sendOut:
    SHIFTOUT outData,outClock,MSBFIRST,[valves]
    PULSOUT OUTLoad,1
  RETURN
  
  getSwitches:
    PULSOUT inLoad, 5                            ' load switch inputs
    SHIFTIN inData, inClock, MSBPRE, [newSW]     ' shift them in
  RETURN
  
  readPot:
    HIGH pot ' charge the cap
    PAUSE 1
    RCTIME pot, 1, onTime
    onTime = onTime/3
    DEBUG DEC ? onTime
  RETURN
  

  bs2

  bs2

  Combined Pumps.bs2

  3K

  Combined Pumps.bs2 3.1K
• alnajjar1 Posts: 110

  2013-08-26 18:37 edited 2013-08-26 18:37

  This is awesome! it makes perfect sense...very elegant.
  
  I will try it and report back.
  
  Many thanks Sapphire.
  
  Al