5x7 LED Matrix Scrolling Display

[manwolf]

Sorry for the hasty remarks. I will dig more and see what I can find online regarding using 74HC425 chips and Pic Chips to control a string of LEDs.

I am very new here myself. I will share what I have found over the years and in my short time here.

People don't mind helping, but they hate doing it for you.

The link you provided is dead, you have some 'kit' you bought and no documentation for it. You are not sure what PIC you want to use.

You are requesting help, with no information to start with the standard help around here is 'Blinky'.

I program for a living and buld electronics as a hobby.
When I started I bought PBP, 2 development boards and a hand full of PICs. I browsed this site and read a LOT of posts. Once I thought I might have enough info, I cracked open the ugly green book and the manual for the development board.

I tried 'Blinky' and guess what it didn't work much to my surprise. Came back here and searched for all the blinky posts. Oooops found out I had not configured the PIC right.
To make matters worse I had two development boards and they both work differently and I also have to different compilers I will not even begin to talk about those.

After Blinky and then Blink 2 LEDs, and so on I worked my way up to try the LCD. I spent hours trying everything I could and at last broke down and posted to the forum. Posted my code and which development board I was using and described my problem.

If you locate that post you will find hints as to what my problem was, but I had to work it out on my own. The answer was there just not spelled out in so many words.

The only way a person can learn is to crawl in and get up to their necks in it.

Read this forum and count how many posts begin; I need code for my class project that is due tomorrow. Help plz.

At times it can get a little chilly around here, but the members on this forum go the extra mile for people who are really trying.

Step into my palor said the spider to the fly. Go ahead Roy you stuck your head in, go for broke.

p.s. I decided on a PIC16F887 to start with it has just about everything you can cram into a chip.

[Archangel]

p.s. I decided on a PIC16F887 to start with it has just about everything you can cram into a chip.

#1 reason most PIC books use the PIC16F84, old Grandpa has near nothing to get in the way of a newbie's success.
Patrick Pending, I am into this 2 years this month, still fumbling and learning, still putting in "temporary blinky code" in my projects.

[Patrick Pending]

Yes Joe, I agree. The 16F84 is plain Vanilla and a good place to start. You can of course get PICs with more functions, more code space, more I/O pins and all that at a cheaper price, but that is not necessarily what a beginner needs. The additional functions mean additional complexity either in setting them up or even just disabling the functions your not using.

Today I was using (the humble) 12F509 for the first time. I had RTFM and subsequently set weak pull-ups and configured the TRIS register for the appropriate I/O. But, I just couldn't understand why my simple program wasn't producing an output on GP2. So, I added a temporary blinky on another pin and that was working. I redirected the output to that pin and my program was definitely working. I knew it had to be down to configuration. It was time to RTFM (again!) or more accurately RTFDS (...Data Sheet).

And there it was a small note on page 24 of 98:

<i>Note: If the T0CS bit is set to ‘1’, it will override
the TRIS function on the T0CKI pin.</i>

Bingo! I disabled TOCS with OPTION_REG.5 = 0
My program was now working properly

To get to the point I was trying to make - it is precisely these sort of quirks that stop a newcomer dead in their tracks, with a little bit more experience you can find your way round them. So I think a "plain Vanilla" chip is best to start with, get your feet wet, then move on to something slightly more advanced.

[roycarlson]

I guess I was more fustrated at the ebay vendor for not providing the code or schematic.

If these is a way to paste a picture here I would. I have a few 16F887 and 16F877 40 Pin Pics laying around to use. I am trying to figure out how the board has the two 74HC425s configured as it appears it is using Pic Pins 2-5, 7-11 and 15-25 for the columns via the transistors (20) to the LED columns.

It also looks like pins 33-39 are connected to pins 2-8 of the 74HC425 chip #1 while there is crossover to the second HC425 chip via pin 2 to pin 18 on chip #2.

The LED Matrix have red or green outputs which are controlled by toggle switch. And it appears swith 29 & 31 are conected to ground via push button switches.

** Is there a way to paste the photo of the board?

[mackrackit]

If these is a way to paste a picture here I would.

Have a look at this thread. Talks about inline pictures. Or just do an attachment.
http://www.picbasic.co.uk/forum/showthread.php?t=9156

[mackrackit]

I have not been able to find the data sheet for the shift register you have.

Basically there are three pins on the shifter that need controlled and one sometimes two can be paired up when using multiple shifters. (shifters being in or out).

If I remember correctly, parralax has good documentation somewhere about how to make a shifter work with a stamp.

If someone else does not get to it first, I will dig up a snippet when I get home and post it for you.

[mackrackit]

Here is a little bit that may get you started. The PBP manual will help to explain some.

'Pin setup
    include "modedefs.bas"
' The clock and load pins can be shared_
'on all shifters
'Data pins are for each shifter
    Clock   var PORTB.7
    Load    var PORTB.6
    Data_1  var PORTB.5
    Data_2  var PORTB.4
    LEDs_1  var byte
    LEDs_2  var byte
'Send data to the shifter
    pulsout Load,1
    shiftout Data_1,Clock,MSBPre,[LEDs_1]
    pulsout Load,1
    shiftout Data_2,Clock,MSBPre,[LEDs_2]

Now the fun part, if you have the data sheet for the shifter it will help.
If it is a serial to parallel register, sending the value of 2 should make the first output pin on the shifter go high, a value of 4 activate the second pin, a value of 6 both pin 1 and 2. And so on. Each pin up is double from the last. To send to multiple pins, add the values for each pin. This is the same for shift in registers.

This is interesting
http://www.eelab.usyd.edu.au/digital...egister03.html