weird problem with dot matrix and shift register

[Darrel Taylor]

I think you just need to "Blank" the rows before changing the Column data, then turn the next row on.

Try it like this ...

FOR CNTR2 = 0 TO 100
  FOR CNTR1 = 0 TO 7
    STRB = 0
    COL = COLVAR[CNTR1]^255
    SHIFTOUT DAT,CLK,0,[COL]
    PORTB = 0                   ; blank all Rows
    STRB = 1                    ; latch the data
    PORTB = DCD CNTR1           ; turn on next Row

    PAUSE 2
  NEXT CNTR1
NEXT CNTR2

[Ahmadabuomar]

Darrel,

thx alot for helping, it worked really well.

i always wished to thank you in person. cuz from 3 years i enter this forum as a visitor and i always see ur post. you always find the solution. thx much Darrel.

still i have a problem i didnt mention. the first row always doesnt give full brightness when it is on. i suppose this relates to the previous problem. i will try to work it out.

thx again Darrel.

BW

[Darrel Taylor]

Thanks Ahmadabuomar, and your welcome.

First row's dimmer than the others ... ok.
Let's try moving the "blanking", so that all the rows are ON the same amount of time.
It should actually dim the other 7 rows to what the first one was.

FOR CNTR2 = 0 TO 100
  FOR CNTR1 = 0 TO 7
    STRB = 0
    COL = COLVAR[CNTR1]^255
    SHIFTOUT DAT,CLK,0,[COL]

    STRB = 1                    ; latch the data
    PORTB = DCD CNTR1           ; turn on the Row
    PAUSE 2                     ; LED ON time
    PORTB = 0                   ; blank all Rows

  NEXT CNTR1
NEXT CNTR2

[Ahmadabuomar]

Hi Darrel,

in fact, row 1 problem was not related to software!! after i tried your last code. i found nothing changed.

I then checked all npn transistors used in rows. i found the transistor on portb.0 is not working properly !! i changed the transistor and the problem was solved.

all portb transistors were bc337 25 npn transistors except portb.0 that was bc337 40

i dont know if 40 is different than 25 !! but i think the transistor itself is not working

thx Darrel for your help

BW