Very basic prop code help

Comments

• SRLM Posts: 5,045

  2009-09-13 07:20 edited 2009-09-13 07:20

  Congratulations for massaging the text code to align correctly. Next time though you can use [noparse][[/noparse] code ] tags (without the spaces) to preserve formatting. [noparse]:)[/noparse]
  
  1. The pin is toggled using the ! (not) operator. Basically, it converts a 1 into a 0 and a 0 into a 1, which when done to outa will make it high or low.
  2. There is no "return" function. What did you mean by this?
  3. The loop repeats count number of times, however many times that is (10 and 20 for this code)
  4. The toggle function ends when the loop finishes, and will go into a limbo state since there's nothing else to do.
  5. VAR where?
• whiteoxe Posts: 794

  2009-09-13 07:39 edited 2009-09-13 07:39

  Whoops ! I meant REPEAT. i Have another Question about the code but I;ll ha ve to post it a bit later.
• whiteoxe Posts: 794

  2009-09-13 15:32 edited 2009-09-13 15:32

  VAR
  ·· long Stack[noparse][[/noparse]9]
  PUB Main
  ··· cognew(Toggle(11001100,3000000,10),@Stack)
  ··· Toggle(11110000 ,2000000,20)
  PUB Toggle(Pin,Delay,Count)
  ··· dira[noparse][[/noparse]pin]~~ 'set to output
  ··· REPEAT Count
  ······· !outa[noparse][[/noparse]Pin]
  ······· waitcnt(Delay + cnt)
  
  
  When cog 0 Pin of 11110000 goes through the REPEAT loop Twenty times·!outa changes the Pin value to
  00001111. But does'nt the pin value stay at 00001111 for each pass ?
  
  Also the manual says the delay , in the case of cog 0 ,of 2,000,000, is the number of clock cycles for the delay. But if that was so there would be no need for + cnt . So does the clock count up to 10,000,000
  and then starrt from 0 again ?
  
  
  Ps. I just used random binary numbers in the above. I dont understand Binary if you have a tip where I can learn this I'll follow it up.
  
  Post Edited (thewhiteoxe) : 9/13/2009 3:38:11 PM GMT
• SRLM Posts: 5,045

  2009-09-13 15:44 edited 2009-09-13 15:44

  Remember that when you use the index operator ( brackets, [noparse]/noparse ) that it returns a single value at the index. In the case of one of the registers, it's a single bit. So !outa[noparse][[/noparse]pin] will change just a single bit.
  
  Read the waitcnt description in the manual. It says that waitcnt waits for count to be equal to the argument, so if you just put in 2_000_000 then it will wait for the clock to equal that. If instead you add it to cnt, then it will effectively wait for 2_000_000 cycles, then continue.
  
  For learning binary, just google binary tutorial. There's lots of stuff out there; find something that works for you.
• whiteoxe Posts: 794

  2009-09-13 15:49 edited 2009-09-13 15:49

  Thanks for the clarity, I should have realised to google the Binary, and for the tip about only changing a single Bit.
  
  Was I correct about the value staying the same for each loop in REPEAT ?
• SRLM Posts: 5,045

  2009-09-13 18:31 edited 2009-09-13 18:31

  The bit given by pin of outa will have two different states in the loop (0 or 1). This is due to the ! (not) operator changing outa between the two states. Delay is constant, and I'm not sure about count. My guess is that count is constant.
• W9GFO Posts: 4,010

  2009-09-13 18:33 edited 2009-09-13 18:33

  thewhiteoxe said...
  Thanks for the clarity, I should have realised to google the Binary, and for the tip about only changing a single Bit.
  
  Was I correct about the value staying the same for each loop in REPEAT ?

  
  Picture a row of 32 light switches on a wall. Each switch has a number (1 to 32) so that each switch corresponds to a pin on the Propeller chip. We will call this row of switches "outa".
  
  If we want to turn every switch on we would say "outa ~~", to turn them all off, "outa ~"
  
  To turn on a group of switches we could say "outa[noparse][[/noparse]4..6]~~" That would turn on switches 4, 5 and 6.
  
  To turn on just switch 17 we would say "outa[noparse][[/noparse]17]~~".
  
  To change switch 17 we say "!outa[noparse][[/noparse]17]".
  
  "pin" does not change within the repeat loop. "pin" is like the number on the switch, not the position the switch is in.
  
  Rich H
  
  ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
  The Servo Boss, a 12 channel servo tester kit from Gadget Gangster.