16F877 universal PCB with I/O module

[jrudd]

Joe,
I'm interested in your board. I'm working toward a small board with 16x2 LCD,
2 or 3 a/d inputs and possibly a PWM out.
Couple of questions:
1. What size is the board
2. How does the LCD connect. I haven't found an easy way to accomplish that yet
Thanks,
John

[Art]

I have downloaded the schematic, and it looks good.
Helped me make a board using F877 for the first time.

Just a Q for anyone who can answer, is there a reason why the two pins
used for comm with the EEPROM would be sourced
from an 8 bit port rather than portA 5 bit port? Using two pins from an 8
bit port seem a waste of a port that has byte-wide I/O potential.

I would like to use A0 as a sink for indicator LED,
A1 SDA, A2 SCL, A3 SDA, A4 SDL for IIC EEPROMS.
Is one of the portA pins only an input?
Cheers, Art.

[mister_e]

The main reason IMHO is because the PORTA is analogue so, when you need to read an analogue signal and you have your EPROM attach to, you're in the FadeleeFadelaa!

[Art]

There is an small error where portd5 is labled c5 on the picture of the pic.
This error caused my house to burn down. will you pay for damages?

Just kidding, since I want all digital ports I started from porta.

are the resistors connected to a5 there to set a reference for analogue ports?

[cupajoe]

Art,

The resistor network on A5 can be used to monitor the input voltage.

Sorry for the small error. You are correct the schematic has D5 mislabeled.

As for why I used two pins of port C to conrol the SEEPROM...well those are the SSP I2C pins for clock and data.

I had good reason for using most of the pins the way I did. I left A4 unused but I wanted to set it up as another output but just never got around to it. A4 has an NPN open collector output. Very handy.


Please post any questions. I can't promise I will answer in a timely manner but I will eventually check back here.

Regards,

Joe.

edit: I almost forgot. Analog ports are very powerful/useful. I use them alot.

[RFsolution]

Do you have any pcb layout available ?

[cupajoe]

I still use this board in commercial projects and I can't make the artwork freely available. I can tell you that it is a breeze to layout. I have posted the silkscreen images and I can sell the boards (at a little over my cost plus shipping). PM me if you are interested in purchasing. I also have I/O modules that interface with the univeral 877 board.

Hope this answers your question.


Joe.