All PIC pins outputting low voltage

[The Master]

Hi, This is a bit of a weird problem. Ive made a circuit using a PIC18F2420. 16 of the pins connect to transistors and LEDs through seperate resistors. 2 pins connect to a tri-color LED and 4 pins are used to connect to an RS485 chip. When i turn the circuit on all of the LEDs light up feintly. When the PIC turns an output on then the LED glows as normal. Its definately the PIC thats causing it because when i remove the PIC all the LEDs go off completely.

Ive tried eliminating possible causes. There is a huge transformer next to the chip so i tried removing it and running from another power source. Ive tried removing the RS485 chip, swapping the PIC and ive been over and over the PCB layout and i cant see anything wrong.

Are there any special configuration registers i might have missed? Ive disabled the analog stuff already. I dont have a schematic at the moment but ill make one up tomorrow just incase it is a design fault.

[mackrackit]

Code????
Maybe?
TRIS

[sinoteq]

Hi
What kind of transistor do you use? Part number? Please post schematics because this smells HW problem. Do you use MOSFET transistors perhaps without any pulldown restistors to the "Base"?

[The Master]

The tris registers are set correctly.

The transistors are MPSA13. I dont use a pulldown resistor on them but i did try adding one and it had no effect. Even the outputs that dont connect to a transistor have this problem too.

Im just going to start the schematic now. It should be done soon

[The Master]

Ive finished the schematic. Its not very good but hopefully youll be able to understand it

[The Master]

Ive tried removing the PIC from the PCB and putting it in a breadboard. Ive connected wires for power, crystal and just 1 LED and i get the same problem. I even tried one of the LEDs that isnt also connected to a transistor.

[The Master]

Hi, I figured out what the problem was. One of the tracks on the PCB wasnt connecting properly which meant the PIC didnt have ground at all so it was getting its ground through the LEDs that were off.

Sorry to bother you all and thanks for helping

[Dave]

The Master , I also notice on your schematic that all of the led anodes on the bottom and the top of the drawing are tied to ground.....

Dave Purola
N8NTA

[The Master]

Ahh, thats an error in the schematic. They are correct in the real circuit.