Counting better ?

[yettie]

franko,

what is your configuration for you PORTA inputs? did you used a pull down resistor to ground? You have an alternative to use internal weak pull-up features (OPTION_REG=7). PIC have sensitive inputs if you used pull downs. I had some problems that I also count the noise spikes if i used external pull downs, and most likely in activating motors. the motors are inductors that could spread some unwanted signals seen by the microcontroller. proper hardware design could prevent this kind of problems.

also, use

  ...(code here in betweens)

for ease. thanks

regards,

[Franko]

Hi Yettie,
The config for porta pins are as inputs (if I did the code right).inputs A.1 and A.4 are pulled high via a 470 ohm. A.0 is pulled low via a 470.

I've never tried setting the internal pull up/dn but I will.The motor is power by a seperate 24vdc supply but with a common ground.The motor is switched by a relay which is controlled by the PIC via a NPN transistor and the coil of the relay has a diode across the coil and is correct direction.

I presume the problem is with the way I've done the code as I'm still learning (and loving it). I'll use the Quote function in the future as you said.

Thanks for your ideas.

[Franko]

Is it that no one sees anything wrong with this ? There must be something wrong with how I've done it.

I'm not asking for anyone to write it for me,rather just some advice on the correct way to make the motor low after four (or whatever) pulses.

  runit:

High Hmtr 
Pause 100
While DATAPLS=0 'wait for High from passthru opto 
Wend
GoSub cnt

GoTo runloop


cnt:
PulsIn DATAPLS, 1, i
IF i > 4 Then
Low Hmtr
Else
GoTo runit
EndIF
Return

Thanks

[CocaColaKid]

Isn't using a 470R resistor a little low for a pull-up? Using a value this low will only increase the current the IO has to produce in order to change the pins state.

[yettie]

franko,

some points:
- cokekid seems to be right. try to increase the pull-up to 10K.
-

Problems are,it stops the Hmtr at three pulses instead of four and if the beam isn't broken in quick succession,hmtr continues to run no matter how many times beam is broken.

seems to be your PULSIN DATAPLS,1,i is the culprit. if theres anyway you can monitor your WORD "i", verify it. If you have a serial port, plug it. otherwise you'll be convinced of what you will find out. then recode. it's my style of debugging.

[Franko]

Yeah, I agree with you CocaColaKid and yettie, I usually use 1K or 10K (depending).But, I breadboarded this kinda quickly and grabbed what I had the most of.

I'll switch them to 10K and see if that makes any difference.

Yetti, I'm not sure what you mean by...

" seems to be your PULSIN DATAPLS,1,i is the culprit. if theres anyway you can monitor your WORD "i", verify it."

But I'll keep trying different methods.

Thanks for the advice,
Franko

[yettie]

franko,

good day!

i mean, i think that your PULSIN method is the problem. try to monitor your variable WORD 'i' after your PULSIN method, such as,

     ...
     PULSIN   DATAPLS,1,i
     SEROUT2 porta.0,16780,["i: ",#i]      ;connect to hyperterminal at 2400, 8N1, no parity.
     ...

just like that.

also I'm in doubt of what you are doing. are you actually trying to count the number of pulses at DATAPLS pin? when you use the PULSIN method, you are actually measuring the period of high signal (since your second argument is '1': PULSIN DATAPLS,1,i). if your period is less than (40us at 4MHz) it will never satisfy your IF statement, therefore the motor will not stop. hope i enlightened your mind, somehow.

regards,

[Franko]

Yettie,
Your right, I'm going about it in the wrong way. I am trying to count the pulses at the DATAPLS pin, NOT to measure the time it's high.

You have indeed enlightened me, I'll keep working at it.

Thank you very much !