Inverted Output on PropRPM Board?

deiloohay

Using this code:

---

VAR
· BYTE· inputPin
PUB ButtonLed····················· ' Pushbutton/Led Method
··· inputPin := 0
··· dira[noparse][[/noparse]inputPin] := 0
··· dira[noparse][[/noparse]25]· := 1··
··· KeepLooping
PUB KeepLooping········································
··· repeat························ ' Endless loop
····· outa[noparse][[/noparse]25] := ina[noparse][[/noparse]inputPin]··· ' Copy P21 input to P6 ouput··

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after F10, the LED on pin 25 lights up, even with pin 0 grounded or connected to ground via a 10k resistor.· i've used a scope to verify this pin is logic 0.· voltmeter agrees....·

Mike Green

How is the LED connected?

stevenmess2004

The schematic is here www.parallax.com/Portals/0/Downloads/docs/prod/prop/proprpmv10_schema.pdf

It look like it is wired up so that the LED will come on when the pin is low which is what you are seeing.

deiloohay

Would putting the first pin on the SIP resistor network to ground instead of vcc and flipping the led bar put this in non-inverted mode safely?

Is there an advantage to this configuration that this would defeat?

stevenmess2004

The advantage is that any cog can turn the led off. This type of display is called common anode because all of the anodes (positive sides) of the LEDS are connected together. You want a common cathode where all of the cathodes (negative sides) of the LEDs are connected together. You should be able to get one of these from your local electronics store.