Just need to clarify...

[rsocor01]

Tazntex,

In your first post you said

I understand how it repeats until i is equal to 7 then moves on but what does the [i] in PORTB.0[i] do?

Technically speaking, it repeats until I=8 then it exits the loop. Of course, it won't execute the line PORT[I]=0 for I=8.

Robert

[tazntex]

Thanks goes to all for you help and interest.

[MOUNTAIN747]

While were on the subject of Port.Bits. I would like to use a random generator to set a single bit in an output port while working with an 8x8 dot matrix display. Is there any way to use a VARiable to set a RANDOM single Bit on an output port?

[aratti]

Is there any way to use a VARiable to set a RANDOM single Bit on an output port?

Ran_Word var word

Ini:
RANDOM Ran_Word
pause 100
PortB = Ran_Word.byte0
Pause 100
PortB = Ran_Word.byte1
Goto Ini

This code should suite your need.

Al.

[MOUNTAIN747]

Al, thanks for your replay. I ran your code. it sets the whole port at a random value. I need to figure out how to set a single bit within the port. I want to turn on a single led on the 8x8 display, then PAUSE, then loop to routine. Any idea how to single out one bit randomized?

[aratti]

I want to turn on a single led on the 8x8 display, then PAUSE, then loop to routine. Any idea how to single out one bit randomized?

This has been shown at the begining of the thread. Anyhow in your case:

Ran_Word var word
AA0         var Byte

Ini:
RANDOM Ran_Word
For AA0= 0 to 7
Pause 100
PortB.0[AA0] = Ran_Word.0[AA0]
pause 100
PortC.0[AA0] = Ran_Word.0[AA0 + 8]
Next AA0
goto Ini

In the above example I assume you are using portB and PortC, if not then change them as per your need.

Al.

[Bruce]

Try this;

X VAR WORD
OldVal VAR BYTE
PortVal VAR BYTE

TRISB = 0

Main:
   RANDOM X
   PortVal = DCD X.HighByte       ' get bit #
   IF PortVal = 0 THEN Main       ' value should always be > 0
   IF OldVal = PortVal THEN Main  ' value should be different on every pass
   PORTB = PortVal
   OldVal = PortVal               ' record old value for next pass
   PAUSE 200
   GOTO Main

   END

[MOUNTAIN747]

Al, closer but not there yet. Sorry for the delay, I had to adjust your code to invert the Collumn port for this display. Bruce I haven't tested yours yet but I had started in that direction.

Bitgenerator:
Bvar=-0
random Ran_Word
Avar= Ran_Word.byte0
if Avar.0=1 then Bvar=Bvar+1
if Avar.1=1 then Bvar=Bvar+2
if Avar.2=1 then Bvar=Bvar+4 ;isolate a random number 0to7
Cvar=1
Cvar=Cvar<<Bvar ;set a single bit in the byte
Cvar=Cvar^$FF ;invert for a low on one bit
rcol=Cvar ;set port
Bvar=0
random Ran_Word
Avar= Ran_Word.byte0
if Avar.0=1 then Bvar=Bvar+1
if Avar.1=1 then Bvar=Bvar+2
if Avar.2=1 then Bvar=Bvar+4
Cvar=1
Cvar=Cvar<<Bvar
Row=Cvar
pause 100
goto Bitgenerator

(Wierd: code tag nor the editor would accept << in the code)


this method works (sorry you can't see all the code) but gives some repetition in general pattern on the diagonal. I will use the DCD. I'm still trying to understand Al's "Ran_Word.0[AA0 + 8]" . What is this doing to the PortC.0[AA0], is it resetting to a number less than 8?
thanks guys, I'll have to chew on this for a while.