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strange behavior Prop Demo Board, RevF — Parallax Forums

strange behavior Prop Demo Board, RevF

CrosswindsCrosswinds Posts: 182
edited 2009-10-07 11:53 in Propeller 1
Hello!

I have just played around with the exercises in the Prop manual, and then i noticed that when i activate any of the LED´s on p18toP23, it activates the LED "under it self"

I.E:

I tell it to activate the P23 LED, the P23 lights up, and so does the P22, but the p22 lights with half the strenght of p23.

It does this all down to 18
. 17,16 is just fine.

tried this on my fathers board, and it does the exact same thing.

It shouldnt be this way right?

Comments

  • kuronekokuroneko Posts: 3,623
    edited 2009-10-06 00:08
    IIRC it's to do with how the demo board's LEDs are wired. If you leave the other LED pins as inputs you'll see the half on effect. To sort this out set all LED pins as outputs (that usually resolves it for me). P16 and P17 have dedicated pins so they just work on their own.
  • WBA ConsultingWBA Consulting Posts: 2,935
    edited 2009-10-06 00:11
    That is correct. If you notice on the Demo Board Schematic, you will see that the LED on P18 is also tied through the 470/240 DAC resistors for the VGA output to the LED that is on P19.

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  • CrosswindsCrosswinds Posts: 182
    edited 2009-10-06 23:38
    Thank you guys for the information!

    Now it works like a charm [noparse]:)[/noparse]
  • Toby SeckshundToby Seckshund Posts: 2,027
    edited 2009-10-07 11:53
    I used two seriesed diodes from the R, G and B oututs down to ground. The 1.4V doesn't affect the video and is below the threshold of the LEDs.

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