5x7 LED Matrix Scrolling Display

[roycarlson]

First - I am new to PBP and Pic Chips and only have little experience using the Basic Stamp from Parallax. It was suggested to me to switch to PBP and Pics if I truly wanted to learn how to use the chips in various applications.

Now - I have purchase PB Professional and upgraded to 2.50, purchased the Pickit2 from MicroChip along with getting several Pic Chips from 8 to 40 pins to play/program with.

I was starting to learn to program the Parallax SX using SX Basic so I switched and sold all my Parallax items to focus and learn Pic Chips using PBP.

I have always wanted to develop a 5x7 LED scrolling display and have purchased and built a kit that include 4ea 5x7 LED modules, a socket for a 40 Pin Pic and two 74HC425 chips for shifting the row data. As this was purchased on ebay, I now come to learn there wasn't any sample software or preprogrammed Pic Chip to experiment with.

My questions is this:

I would like to have help or sample basic program to experiment with this board using either a 16F877 or 16F887 chip. The board is complete and has 4 5x7 RG LED modules in place along with 2 switches (power/red or green selector) and 3 additional switches that can be used within the program to select subroutines or text to display.

If you go to this website you can find the schematic of the board: www.rafatronics.com

[skimask]

I have always wanted to develop a 5x7 LED scrolling display and have purchased and built a kit that include 4ea 5x7 LED modules, a socket for a 40 Pin Pic and two 74HC425 chips for shifting the row data. As this was purchased on ebay, I now come to learn there wasn't any sample software or preprogrammed Pic Chip to experiment with.

That's what you get with flea-bay...

I would like to have help or sample basic program to experiment with this board using either a 16F877 or 16F887 chip. The board is complete and has 4 5x7 RG LED modules in place along with 2 switches (power/red or green selector) and 3 additional switches that can be used within the program to select subroutines or text to display.

You'd learn a heck-of-a-lot more by writing code that doesn't work, posting that non-working code, and asking for assistance in figuring out why it doesn't work, than you would if you were to just cut-and-paste somebody else's working code...unless all you really want is instant gratification...
A lot of people here know a lot of things about a lot of stuff. And I will suggest, heavily suggest, starting off simple and slow, blink one led, blink 3 leds, blink 3 leds and control them with a couple of switches, and so on and so on.

www.rafatronics.com

Ya, that doesn't work so well..

[Patrick Pending]

I agree with Skimask.

Start at the beginning and work forwards, it is essential to understand the basics before you try to grapple with anything more complex.

Good luck

[roycarlson]

Sorry Guys,

Please forgive me for stepping on your skills and asking for direction to some sample code to use as a backdrop to getting a 5x7 Matrix Display working.

I know I should learn from scratch all over again as I spent last year working through several of Parallax's beginner courses to get the basics. I am neither a software or microchop professional - only a hobbyist looking to learn to build things and have fun.

It is probably me that is in error - but your replys seemed to condem me for not starting with the basic lesson (which I did by buying two books and the PicKit2 along with the 44 Pin demo board.

Moving over from Parallax Basic to PicBasicPro is very different in that a lot more pre conditioning has to take place for the software to work with the many different chips that are out there to use.

I have also gone through lessons using PicAxe chips and was directed to PBasic & Pics by Reynold's Electronics as a means to save money - not true.

All I wanted to know is if anyone has developed software to run 4 - 5x7 LED Matrix Displays and what 40 Pin PIC would work best to program. I stated that the board I purchased and built uses 2 74HC425 chips to control the rows and 20 3904 transistors to control the columns.

The website listed for the part I built was working when posted.

IN CLOSING - HOW DO I REMOVE MY POST OR EDIT?

[Archangel]

Sorry Guys,

Please forgive me for stepping on your skills and asking for direction to some sample code to use as a backdrop to getting a 5x7 Matrix Display working.

I know I should learn from scratch all over again as I spent last year working through several of Parallax's beginner courses to get the basics. I am neither a software or microchop professional - only a hobbyist looking to learn to build things and have fun.

It is probably me that is in error - but your replys seemed to condem me for not starting with the basic lesson (which I did by buying two books and the PicKit2 along with the 44 Pin demo board.

Moving over from Parallax Basic to PicBasicPro is very different in that a lot more pre conditioning has to take place for the software to work with the many different chips that are out there to use.

I have also gone through lessons using PicAxe chips and was directed to PBasic & Pics by Reynold's Electronics as a means to save money - not true.

All I wanted to know is if anyone has developed software to run 4 - 5x7 LED Matrix Displays and what 40 Pin PIC would work best to program. I stated that the board I purchased and built uses 2 74HC425 chips to control the rows and 20 3904 transistors to control the columns.

The website listed for the part I built was working when posted.

IN CLOSING - HOW DO I REMOVE MY POST OR EDIT?

Hi Roy,
I would ask that you reconsider, I do not believe anyone is condemming you, So many beginners come with wide eyes and plans for projects beyond their abilities and end up frustrated believing this is impossible, that's all. That said here is a link for starters:
http://www.picbasic.co.uk/forum/showthread.php?t=3739, as I get time I will look for others.
Oh and speaking of Bruce, here is a tidbit ON HIS WEBSITE : http://www.rentron.com/PicBasic/Movi...ge_Display.htm there appears to be more than 1 example here including links to one in C.
http://www.picbasic.co.uk/forum/showthread.php?t=6033
here is something using shift registers: http://www.instructables.com/id/LED-...ift-registers/
using PIC:http://www.instructables.com/id/EI8L4C81FIEV2ZF7JP/

<marquee scrolldelay="125" width="50%"> Nobody leaves here hungry, unless they want to. </marquee>

[skimask]

If you'll re-read my post, you'll find little negativity directed squarely AT you...

That's what you get with flea-bay...

Generic eBay contempt. You get what you pay for. Buyer beware. That sort of thing.

You'd learn a heck-of-a-lot more by writing code that doesn't work, posting that non-working code, and asking for assistance in figuring out why it doesn't work, than you would if you were to just cut-and-paste somebody else's working code...unless all you really want is instant gratification...

Generic 'the way things are these days' statement. If you wanted an pre-built pre-programmed project, I'm sure there's a 100 different places to buy stuff like this. And it'll most likely save your money buying stuff you end up not needing and your time trying to learn.

A lot of people here know a lot of things about a lot of stuff. And I will suggest, heavily suggest, starting off simple and slow, blink one led, blink 3 leds, blink 3 leds and control them with a couple of switches, and so on and so on.

Again, if you want to learn, post some non-working code that you may or may not have written. You'll get hints on how to make it work, heck, maybe even a link to a working solution if your lucky.

Ya, that doesn't work so well..

Just saying that link to that website was dead.

Please forgive me for stepping on your skills

Ain't stepping on anybody here...at least I don't think so...

and asking for direction to some sample code to use as a backdrop to getting a 5x7 Matrix Display working.

Sounded more like asking for working code to a finished project.

I know I should learn from scratch all over again as I spent last year working through several of Parallax's beginner courses to get the basics.

The PIC and PBP are a far cry from the Stamps and the like. With the stamps, you tell the taxi where you want to go. With PBP, you have to give the taxi driver directions.

I am neither a software or microchop professional - only a hobbyist looking to learn to build things and have fun.

That's exactly what the overwhelming majority of us here are...hobbyists. Only a few people around here are in it for the money.

It is probably me that is in error - but your replys seemed to condem me for not starting with the basic lesson (which I did by buying two books and the PicKit2 along with the 44 Pin demo board.

Question is...Did you actually start with the basics or jump into the deep end expecting everything to work the first time around?

All I wanted to know is if anyone has developed software to run 4 - 5x7 LED Matrix Displays and what 40 Pin PIC would work best to program. I stated that the board I purchased and built uses 2 74HC425 chips to control the rows and 20 3904 transistors to control the columns.

Again, sounded like you wanted a finished product.

The website listed for the part I built was working when posted.

Ya, it happens...

IN CLOSING - HOW DO I REMOVE MY POST OR EDIT?

No need for that...

[Bruce]

Dang Joe, you're getting good at posting here. The scrolling text thing was pretty cool..:}

Roy;

Don't get upset by what people post here in response to something you're looking for that's relatively complex, especially when the link you provide to a schematic isn't available, and no one can download a copy to look at - in an attempt to help you.

Skimask & Patrick Pending both assumed, by your stating

First - I am new to PBP and Pic Chips

that you were a complete newbie, and had no idea how to get started even blinking an LED.

I know this may sound harsh, but it really is excellent advice. Assuming someone's just getting started. Just blinking an LED tells you quite a lot beleive it or not.

1. Your programmer is working as expected.
2. Your config settings are probably OK.
3. Your oscillator is working.
4. The circuit you have assembled is probably OK.
5. Your compiler is working.

And several other things. It's not that anyone here is trying to give you a hard time - they just want to make sure newbies understand a few basic proceedures before they spend a boat-load of time trying to help them figure out something more complex.

If you show some attempt at getting this to work, I.E. you have a simple example of code you have put together that doesn't work, I really think the folks here will jump in head-over-heels to help you get it sorted out.

There's an amazing amount of talent here, and most will do back-flips to help someone out, but they will normally want to see at least a modest effort on the part of the person submitting a request for help first. Not just - here's what I want to do - here's a schematic, give me some code to get started.

I think if you can at least post a schematic, and be specific about what you're looking to do, 'maybe with a note: I have no idea how to get started' - you'll find this forum better than any other you can find.

I have also gone through lessons using PicAxe chips and was directed to PBasic & Pics by Reynold's Electronics as a means to save money - not true.

Which part of this is not true?

A PIC18F2431 costs only $7.68 in qty of 1, and can run rings around the fastest Stamp, and has built in hardware peripherals like timers, counters, hardware PWM, USART, I2C, SPI, motion control module, power control PWM, and a host of other features.

What would it cost to add these peripherals to a $50.00 BASIC Stamp module with zero built-in peripherals? Now figure that times 10 or more projects.

BASIC Stamps are very cool, but a $3.00 PIC can replace one, and it has a ton of built-in hardware peripherals that would cost a lot more to add to any Stamp project. And you're not yanking that $50.00 Stamp module out of every project for the next once since a PIC is much less expensive, and can be left there.

If you're serious about learning this stuff, stick around. There's a lot of talent here just waiting to help....;o}

[roycarlson]

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.

[Archangel]

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.

Good, now we have put all this silliness behind us, Which PIC are you going to use, what kind of oscillator will you use, internal or crystal, what osc frequency, can you post the schematic ?

[Patrick Pending]

Hi Roy,

I had hoped to add a little bit of background about myself when I posted my reply, but my 7-year old was bugging me at the time so it had to be brief.

I started programming PICs about a year ago, so I still consider myself a relative newbie - I'm just a little bit further along the path than you are. I have started a number of projects that I have had to temporarily abandon while my programming skills catch up with my expectations. Initially, I did not take my own advice and started in the middle, working backwards to try and fill in the gaps. I can tell you, from first-hand experience, that this is not the best way to do it. Working this way is frustrating, as the simplest of mistakes (which would be obvious to those who had started at the beginning) can stop your project working.

In case there still remains any doubt let me say that it was good, honest, friendly advice from someone who has been where you have - and I don't mean Milton Keynes ;-)

All the best,

[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

[Archangel]

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

Hi Roy, Hi Mackrackit,
Have you unzipped Trent's 245 LED post, I have , he provides a nice VB program to send data to his display, all the code, a pdf article on building it, and the code is in PBP, a good read to be sure. http://www.picbasic.co.uk/forum/showthread.php?t=6033 BTW that 74HC425 is either very obscure or the number is either been <font color=red>misread</font color> or is someone's house numbered device, without seeing the schematic it is hard to guess what it really is.<br> Mackrackit, thanks for that last post, a good study.

[Patrick Pending]

Hi Roy,

I suspect that the 74HC425 might actually be a 74HC42<b>S</b> in which case it would be a BCD to decimal decoder - which sounds plausible. http://www.datasheetcatalog.com/data.../74HCT42.shtml

here is a circuit that uses them to drive an 8x8 scrolling display
http://www.antrak.org.tr/gazete/1220...image/sema.gif

Here is the supporting text (I hope your Turkish is good )
http://www.antrak.org.tr/gazete/122003/ali_yetis.htm

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