Help with my first PASM code

DRMorrison

Hello,
I'm attempting to write some PASM and need help. This is my first attempt at using PASM, so be gentle.

This is what I'm trying to convert:

PUB MoveCCW(num, spd)


 outa[10..11]~~                  'enable L293D
 repeat num
   outa[14..15] :=                 'output ON
   waitcnt(clkfreq/clkspd + cnt)   'wait
   outa[14..15] :=                'output OFF
   waitcnt(clkfreq/spd + cnt)
   outa[12..13] := 
   waitcnt(clkfreq/clkspd + cnt)
   outa[12..13] := 
   waitcnt(clkfreq/spd + cnt)
   outa[14..15] := 
   waitcnt(clkfreq/clkspd + cnt)
   outa[14..15] := 
   waitcnt(clkfreq/spd + cnt)
   outa[12..13] := 
   waitcnt(clkfreq/clkspd + cnt)
   outa[12..13] := 
   waitcnt(clkfreq/spd + cnt)
 outa[10..11]~                     'disable L293D

This code works as written, and represents one iteration thru the motor's wire combos. My oscilloscope shows the pulse width of the ON
time to be 1.48ms.

This is a method to move a 4-wire stepper in reverse. I have attempted to put something together, but am embarased to show it here.
I've played around with the timing of the 2 vars clkspd and spd, and this seems to be as fast as I can run this motor using SPIN, and
thought PASM might speed things up. Perhaps not?

THanks, Daniel

franksanderdo

Hi Daniel

Don't be embarrassed and show what you have.
It is easier for us here to help you on the first steps of learning curve if we can explain on your code snippet where the traps are hidden.
PASM can be some what confusing in the beginning (I am at the moment just one step ahead of you and got my first routines working)
Actually I am unsung the same approach: First a SPIN routine to test the Idea and after transferring that in PASM.

One question to your SPIN:
what is the difference between spd and clkspd and is that distinction required?

All the Best
Frank

DRMorrison

Thanks for the encouraging words.

spd is the value sent to the method and used as the on-time for the output to the L293D.
clkspd is the constant value used for the off-time of the output.

Pins 14 ,15 are set hi for the waitcnt(clkfreq/clkspd) period, advancing the stepper, and then are turned off. I found that laving these on for too long causes the current to go sky high.
The next waitcnt w/spd is how the user can set a speed for the motor without having the current on during the delay.
Turn on a switch, wait a little, turn off the switch, wait as much as required to achieve the desired speed.

That's a long answer, hope it makes sense.

As far as PASM, I was only able to get one waitcnt. I couldn't figure how to turn on only the 14 & 15 pins, wait, and then turn them off again.

mov          dira, #C00
 mov          outa, #C00


 mov          time, cnt
 add          time, #100
 waitcnt      time, #200
 waitcnt      time, #0

I'm not sure, but I think that this will result in a shorter on time than off. 100-ON, and 200-OFF?
Embarrassing effort.

Daniel

Mark_T

DRMorrison wrote: »

Hello,


This code works as written

The code you've posted however is not legal Spin... Assignments need a RHS...

The basic elements of PASM you need are easy, something like:

                or      DIRA, pinmask    ' set up some pins as outputs
                mov     time, cnt
                add     time, delay   ' setup for initial waitcnt

                ' delay like this:
                waitcnt time, delay    ' where time is already set up, delay is the _next_ delay
                ' manipulate pins like this, where xxxx are bit masks defined later
                or      OUTA, xxxx    ' force pins high
                andn    OUTA, xxxx    ' force pins low
                xor     OUTA, xxxx     ' toggle pins

                ...
delay           long  clkfreq/clkspd
pinmask         long    $0000F000   ' bits 12 to 15 set in the mask

time            res     1

Bean

Mark_T wrote: »

The code you've posted however is not legal Spin... Assignments need a RHS...

I think there is an issue with the forum when you use a % where it doesn't show characters.

Bean

Bean

I hope this helps...

  or outa,enable ' [10..11]~~                  'enable L293D
  mov count,num ' repeat num

again
  'outa[14..15] :=                 'output ON
  mov temp,ina
  andn temp,mask1415
  or temp,outputOn
  mov outa,temp
  
  'waitcnt(clkfreq/clkspd + cnt)   'wait
  mov temp,clkspd
  add temp,cnt
  waitcnt temp,#0

  'outa[14..15] :=                'output OFF
  mov temp,ina
  andn temp,mask1415
  or temp,outputOff
  mov outa,temp

  'rest of code

  djnz count,#again
  andn outa,enable '  outa[10..11]~                     'disable L293D


num       LONG 1000
enable    LONG %1100_00000000  ' Enable L293D
mask1415  LONG %11000000_00000000
outputOn  LONG %11000000_00000000
outputOff LONG 0
clkspd    LONG 80_000 ' 1mSec * clock

temp  res 1
count res 1

Bean

DRMorrison

The spin code works, and the variables listed are brought in through the method call, or are a con set outside the method.
I'm not sure what an RHS is. Could you explain?
I see that the percent sign and numbers that I placed in the original code block didn't make it.
It is suppose to be:

outa[14..15] := *10 'replace percent sign with the * char
here is the MoveCW method as seen in my editor:

Bean, I like the way that you have written that code; it's easy for me to understand.
Also, do I call this just like a spin method? like this?

DAT MoveCCW(num, spd)

  code here
  etc

Thanks, Daniel