okay so i ave done the new schematic with the new chip.
The only place i see a possible error is on the lcd hookup
but other than that it looks good.
The floating cap and pot are to be ignored. they were just floating there to be used to copy and paste the schematic.

 

Not bad. Why not put the switches on one per input pin ra2,3,4,5, much easier to code. Just add a pullup on each input. I'd also stick the LCD RW pin to a spare output say RC0

LCD connect the data lines to RB0,1,2,3 putting the control lines on rb4,5

Most LCD libraries need either the lower or upper 4 bits not in-between bits.

I'd still recommend that unused opamp setup for unity gain to drive ra1

Take a look at the unicorn schematic on my site www.blueroomelectronics.com

 

updating schematic give me about 5 min and that unicorn is basically what i am after with the addition of the opamp. but the price is a bit to high. i am looking to keep the price per unit lower.
But look great. if i was only needing one i would just buy that and add the opamp. but making 50 units or so it seems i am better off making my own. and i will be making more than 50 units in the future.

 

Ra2 thru 5 need 10K pullups to VDD otherwise looks good. To save space use a SIP resistor (can also use for the MCLR pullup)

 

So here is it with more revisions.
Any more advice?

 

Looking good.

 

okay so now i just need some help with getting this thing nice and small in the layout. to bad there was no program that you could give it a schematic and it make layout.

 

ICSP port doesn't look right. Vdd, Vss, Gnd, and ICSPCLK and ICSPDAT

It appears you have the CLK(RB6) and DAT(RB7) lines from the ICSP port attached to the Xtal Oscillator.

Depending on which device you end up using, 28 pin DIP or SOIC, 40 pin DIP, or 44 pin TQFP, the pin numbers for RB6 and RB7 are different.

These also happen to be the pins for the LCD, so simply unplugging the display to program the chip works fine to get around that, as these will be programmed one time once code is settled.

See section 25.7 of the 18F2550 Datasheet

On that note, don't use a programming header with pins permanently on PCB. Just add 5 "pads" at DIP spacing (0.1" spacing, but w/o holes) that the PICKit2/3 can touch when a 5 position male/male header is put in the PICKit2/3 female port instead of adding pins to every board. You only need to hold it steady for a few seconds per board. Saves time and cost when doing many that will be programmed once.

 

okay so now i just need some help with getting this thing nice and small in the layout. to bad there was no program that you could give it a schematic and it make layout.

There is, but it isn't cheap. Multisim Pro with UltiBoard does schematic capture and PCB placement/layout with 3D preview. For a couple grand.

I think there are other alternatives around as well that autoplace/autoroute, and some placement is still manual anyway.

I wouldn't have the LCD or ICSP carved in stone until you find out what language the PIC will be programmed in, and a solid decision on which package IC. SourceBoost C has a library for LCD that uses the 4 bit protocol, other compilers may not be as flexible with assigning ports and pins with their built in libs. The price is also right with SourceBoost, though some prefer MikroC or CCS or C18 or <quite a few others here>

 

im not quite sure i follow you about the icsp.
Might you be able to show me?
also i was thinking of going with this
http://www.microchipdirect.com/productsearch.aspx?Keywords=PG164130
and use MPLAB
i picked the HD44780 due to they seem to be very popular and i can get them cheap. (in orders of 50)

 

im not quite sure i follow you about the icsp.
Might you be able to show me?
also i was thinking of going with this
http://www.microchipdirect.com/productsearch.aspx?Keywords=PG164130
and use MPLAB
i picked the HD44780 due to they seem to be very popular and i can get them cheap. (in orders of 50)

Good choice on Programmer and LCD driver.

I'd almost suggest bumping up one level to get it all in one package. The 44 pin demo board is pretty cool, and you get a limited version of C18 as well as MPLAB and several demos on the disc with it, in addition to the programmer.

Here is an ICSP AppNote from Microchip covering how to set up a PCB for ICSP. It uses 16Fxxx series for examples, but is just as applicable to the 18Fx series as far as connecting to ports goes.

 

okay i read it and it looks like my setup is how its shows it.
Am i think i am still missing it.
i dont have to buy the all in one package do i? i can just download the software and but the programmer.
okay loading

another image of it i cleaned it up a bit so it was less clustered. i think you were getting traces mixed up.

 

All you need is the programmer.
USB is no cakewalk, what language are you planning to program in?

 

i was going to use MPLAB with the pickit3. so i would be using C.

 

C18 is one choice are you a good C programmer?

 

wont the standard PIC18 Development Kit
come with the software needed or do i need to go specialized?
simply put no, i am not, i know people that are tho. i myself find my way slowly threw most things with a book. so i learn as i go the hardest way possible.
I am not half bad at basic for whats thats worth.

 

The main reason to get the programmer with board is the extra known good samples that are ready to run on the 44 pin demo board. Otherwise, just the programmer and downloading the drivers for it is all you need if not experimenting beforehand on a non-production item.

The new ICSP routing looks OK to me in the latest revision of the diagram. Remember the pullup resistors if needed.

 

C18 has a free SE version, it's fine and is the standard C for PIC18.

Dig through the code examples or the UBW (universal bit whacker) for more code examples.

If C's not your bag you can buy Swordfish BASIC as it has a USB module.

 

So as far as a schematic goes this is bug and glitch free?
Its just working out they layout correct?
Sorry so do i not want to use the mplab software are you saying Swordfish BASIC would be a better choice?
the option of price is comming about i can get mplab for free with the kit and all for under 120$ and Swordfish BASIC looks like its a ton more.

 

Looks fine to me but as I've stated before build a prototype before going into production.