Highs & Lows on 18F252

TheRidDler · Guest

Hi there. This is my first post and also first time using PICs, let alone programming them. I have a problem however. I started out by testing
output_high & output_low statements on all the pins. I come across
three pins however that have a high state of Vcc, but a low of Vcc-0.8V.
The pins are C0, C1 and B2. Is there code to of statements that will force
the PIC to drive them to 0V? Thnx alot for your help in advance!

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Post your test program that demonstrates this. (Show all #include,
#fuses, and #use statements).

Post a description of the external circuits that are connected to those pins.

Guest · Posted: Wed Jun 13, 2007 6:20 pm

Test Program:

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Describe the connections to the transistors in more detail.
What pin on the transistor is connected to the PIC pin ?
Do you have a series resistor ?

See this tutorial.
http://www.winpicprog.co.uk/pic_tutorial_extras.htm

Guest · Posted: Wed Jun 13, 2007 7:01 pm

Thanks alot for the link, i needed a couple of resistors to pull them down. Got that fixed now! The following thing im struggling with is setting up 2 software UARTS on my PIC. I've heard of and understand the basics behind it, but could someone mayb help me with a basic setup for a software UART in CCS 4.03? Im sure i can figure it out from a basic example. Im using a 18F252 PIC to receive data on pin A4 from a GPS, then send it via RF (rf tx pin is A0). On the receiving end i have a nRF905 Tranceiver module that handles the interface. Thnx alot!

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

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