Need "PIC16F84A" Controler schematic Advice...

**Kyo** · 05-26-2009, 10:33 PM

Hi Every one,

I am looking to make a controler for My pop up headlights on My car,
just for kicks as I like projects. So I have decided on a PCB board
micro controler DIY project I found online for My car but here comes the bad part
the schematics for the PCB are no longer hosted on the website
I dont know how to draw up the schematics for the Board or for the right parts
but after alot of searching around i have managed to draw up a set of schematics.

Now I Fully plan to use The programe and all the details from the DIY website..

what I would like to know is will this schematic I drew up work for the DIY project
on the Guy's 'website here is a link to the Project I am taking a stab at

http://members.dslextreme.com/users/...leepyeyes.html

be 100% Blunt with me this is my very first project like this and I welcome all and any Advice

when I get all the details worked out I will build it but for my first build I am making a pic progamer...

Thanks for all your advice and help

Cheers
Kyo

**Curiosity** · 05-27-2009, 05:42 AM

Looks good to me, assuming the unlabeled resistors are within a reasonable value. Not sure about the one on drain. You shouldn't need those.

One tip though: The use of the PIC isn't all that great. What I mean is, PORTB looks much better for input with weak pull-up and int-on-change. Many people put resistors on switches, but you can save space/wire by using WPU. Just replace the 5V with ground, and in code enable WPU on PORTB and reverse the branch logic.

**Kyo** · 05-27-2009, 12:27 PM

Curiosity----> Thanks for the advice
how is this set of schematics?? I drew theam up this morning with your advice in mind..

I do have another question tho
What do you mean by "in code enable WPU on PORTB"
as well as by "reverse the branch logic"
Sory for my probaly very Newbe Questions i have only been researching and reading up on all this for the last few days..

Cheers
Kyo

**Curiosity** · 05-27-2009, 01:02 PM

Well, only do it that way if you're comfortable swapping PORTA and PORTB in your code.

It looks like WPU is already enabled which is the movlw 7, movwf STATUS_REG. NOT_RBPU is bit 7.

By reversing branch logic, I mean the bits for the switches will be high when open instead of low, so all the btfsc PORTB, x would be changed to btfss.

Make sure you read all of the datasheet
http://ww1.microchip.com/downloads/e...Doc/35007b.pdf