#80 Scrolling LED Matrix MAX7219 Updated

Подписаться 53 тыс.

Просмотров 18 тыс.

50% 1

More information in my GitHub:
github.com/RalphBacon/Video-8...
It's been a year since my original video on MAX7219 Scrolling Text and this update shows a massive step forwards in ease-of-use by using the 4-in-1 units that are available for around $3.60 (£3.13).
This makes it very easy and affordable to have a decent length of scrolling text to report on the weather, perhaps, or RU-vid statistics, or even the stock market!
I also cover a problem with the original 4-unit display (consisting of four individual 8x8 LED matrix units wired top-to-tail - and a potential solution.
And I cover a less-than-optimal 125kHz RFID reader that whilst very cheap just did not perform as expected.
All sketches used (along with relevant libraries) can be found in the links below, with most of the stuff you need in my GitHub repository which you can download as a zip file.
======================================================
125kHz RFID links 125kHz RFID links 125kHz RFID links
======================================================
blog.deconinck.info/post/2015/...
RDM630/6300 Data sheet
store.iteadstudio.com/images/p...
RDM6300 125Khz RFID library (software serial so you can still upload code using the USB port)
github.com/Seeed-Studio/RFID_...
======================================================
MAX7219 LED links MAX7219 LED links MAX7219 LED
======================================================
Hobby Components forum article on the MAX7219
forum.hobbycomponents.com/view...
Hobby Components MAX7219 library (works with more than four 8x8 LED matrices)
blog.hobbycomponents.com/?p=334
Notes from Nick Gammon on the MAX7219 LED multiplexer (well worth reading)
www.gammon.com.au/forum/?id=11516
Nick Gammon's MAX7219 library (original) for the 4-in-1 LED unit
github.com/nickgammon/MAX7219...
Nick Gammon's Bitbanging SPI library (required for Nick's MAX7219 library)
github.com/nickgammon/bitBang...
My amended version of Nick Gammon's MAX7219 library to work with Eclipse IDE AND have an extra function exposed
github.com/RalphBacon/MAX7219... (zip)
My amended version of Nick Gammon's smooth scrolling sketch to include brightness/speed/switch off controls
and how to concatenate the message string with special characters (like the 'degrees' symbol)
github.com/RalphBacon/MAX7219... (zip)
IMPORTANT WIRING NOTE
Note that where Nick mentions the LOAD pin he means the CS (Chip Select) pin on the MAX7219 displays (they have changed the name, I guess)
Arduino Uno/Nano
Pin 13 - goes to MAX7219 4-in-1 display pin CLK (Clock)
Pin 11 - goes to MAX7219 4-in-1 display pin DIN (Data in)
Pin 10 - goes to MAX7219 4-in-1 display pin CS (Chip select)
If you like this video please give it a thumbs up, share it and if you're not already subscribed please do so :)
My channel is here:
------------------------------------------------------------------
/ ralphbacon
------------------------------------------------------------------
How can I remember this? Memory tip: "See" Ralph Bacon, geddit?

Наука

Опубликовано:

6 апр 2017

Ссылка:

Скачать:

Готовим ссылку...

Добавить в:

Мой плейлист

Посмотреть позже

Комментарии : 155

@johnmellor6065 6 лет назад

really appreciate the quality of explanation and the depth you go to in explaining thanks

@RalphBacon 6 лет назад

Thanks, John, I aim to please! Glad you like it. Merry Xmas.

@MrCatchers 7 лет назад

Hi Ralph, Always good to view a new Video from you, especially this one, long anticipated with an answer to the 4 module limit of the previous sketch. No doubt you will not be surprised to hear that my 5 individual modules are now working using sketch “HCOPTO0014_Serial_Dot_Matrix_Example”. A few pointers after an afternoons pottering that may help other relatively inexperienced Arduino types like myself: (1) The display of the first “HELLO!! “ string scrolls across to module 2 and then stops until another instance of the same string overwrites it. This looks a little messy, so I have inserted an additional ‘HCMAX7219.Clear()’ command at line 73, much tidier. (2) The instructions say to modify the ‘HCMAX7219.h’ header. Not something I have done before, and it soon became apparent this cannot be done in the Arduino IDE. It turns out that these are text files and can be edited with a text editor. My copy of Windows 10 has “SUBLIME TEXT” editor and this displays the file quite nicely. I modified “NUMBEROFDRIVERS” to 5, and simply saved the file. It appears this is interpreted and therefore doesn’t require compiling. Certainly all appears to work. (3) I would like each display string to scroll off the left end of the matrix before another starts. This is clearly tied in with the test in the ‘for loop’ for each string. I suspect there is some sort of connection between the length of the string “HELLO!! “ = 8 and the test of the value of the Position integer (64), but I haven’t resolved it yet. As a test an arbitrary increase in the test value to

@RalphBacon 7 лет назад

Welcome news, MrCatchers, that you got it working. A couple of points then on your post. Nice that you changed the sketch to suit your needs regarding the clearing of the first message. Editing the header file (.h) via the Sublime Text Editor is a great way to do it; but that file is not, however, interpreted, but used as part of the compilation process of your own sketch. It's a library so the compiler drags in whatever code it needs (has been referenced) into your sketch and compiles it. Incidentally, if you look at my video #69 about the Sublime Text Editor you will see that with the addition of an add-in you can use it instead of the standard Arduino IDE. It gives you some extras (such as Intellisense) which makes programming that bit easier. Have a look! If you want to scroll your message off the end you could add a few spaces to the end of your message. A bit trial and error but it seems to work OK for me. Good luck with the new 4-in-1 displays; mine have arrived and I hope to construct my ticker message over Easter. We can compare notes later! Do read the cautionary tale from Matt Cocker here in this thread about zapping your Arduino if you try and power the LED Matrices from the Arduino - always use a separate 5v power supply (that you can also use to power your Arduino but not the other way around). Thanks for posting, nice to hear that you are making good progress.

@MrCatchers 7 лет назад

Thanks for the warnings re pulling excessive current from the Arduino. As it happened, I have measured the maximum current drawn whilst running the sketch and this is 724 mA when powered externally and 615 mA when powered from the 5v power pin on the board. I have read in a number of on-line postings that the 5v pin can provide 800 mA so seem to be within spec (just). However, I take Mat Cocker’s point in that you never know when some sort of glitch won’t cause a surge. All of which would push me to use external power when using 5 display but for a peculiar bug that I cannot fathom the reason for: when externally powered (5v direct to VCC on the left display) The first string “HELLO !!” display fine, but the second iteration of this string (and subsequent for as long as the sketch runs) all start on the second display (from the right), for all purposes the first display is dead. I have checked the voltage on this displays VCC pin and it is 5.15V. When I revert to powering from the 5V power pin all displays work fine. I have been looking at this all week and it doesn’t vary. For the life of me I can’t think of a logical reason that would cause this to happen. Thanks for your explanation of how the library is incorporated into the sketch, that all now makes sense. I looked at video #69, most interesting, probably food for thought once I have more experience.

@RalphBacon 7 лет назад

That is a strange "bug" you have there MrCatchers, I will see whether I have similar issues. Is the external power supply up to the job? The "HELLO" display is quite current intensive, perhaps the voltage drops enough to cause the last display to not receive sufficient? Is the PSU particularly (electrically) noisy? (That's about all I can think of until I try this for myself). Keep tuned for my report!

@MrCatchers 7 лет назад

The power supply is an ATX type removed from an old PC, the 5V output is rated at 40A max, so I would be surprised if this was an issue. Measuring the voltage on the VCC pin of the ‘dead’ display indicates 5.15V exactly the same as VCC on the first (left) display. I have a ‘MAX’ function on my multimeter which indicates 724 mA (predictably when displaying ‘HELLO’ in reverse). Good point re noise, I will see if I can measure it (long time since I had the scope out, it will be fun working out how to do it). I will try an alternative PSU before I go further. Thanks Ralph, as always.

@michaelstevens630 7 лет назад

Ralph be honest and tell us that Benny actually writes all the code. What a clever cat he is.

@RalphBacon 7 лет назад

I'm under a non-disclosure agreement, Michael, and cannot really comment on who writes the code. Let's just say it's normally purr-fect and really is the cat's whiskers (geddit?). As you may have already mentioned I do have to actually type it in (no thumbs for Benny, makes using the keyboard difficult) and operate the camera, but I don't really understand any of it, we might as well be talking about nuclear physics. Thanks goodness Benny has such a high cat-IQ. I'll let him know you appreciate his videos :)

@mdk1515 7 лет назад

Thank you for the videos! enjoy your weekly specials! The ISO standard for Rfid pet chips is on a different frequency 134KHZ.

@RalphBacon 7 лет назад

Hi there, M dk! (I have not idea what that might stand for). I Googled this extensively (for UK pets) and the two frequencies that were suggested were 125kHz and 134Khz (not that the manufacturers were supplying any information whatsoever, of course). I took a chance that the 125kHz might work (you never know, it still might, depending on the chip in Benny, and if I ever get the range to extend beyond 0.5cm). If it doesn't then I'll have to assume that 134KHz is the UK standard, but I haven't found an RFID reader for that frequency (yet - never say never!). If you have a link to that ISO document that would be useful not just to me but others who have also tried 125Khz (which might also be able to detect 134Khz).

@mdk1515 7 лет назад

Dear Ralph, I was also disappointed in the performance of the little Rfid reader (experimented with the same board) to say the least! In my industry (zoo) we are always looking for non-invasive methods to monitor the health of animals. One of the most important is weight that we can assign to an ID (transponder chip) and monitor over time. Shout out to our conservation breeding Centre: www.albustanzoo.com . RFID implanting chips for animal are categorized in ISO (AVID) chips and Trovan Chips both with different frequencies and protocols. Trovan have managed to get patents on the frequency and protocol for their RFID chips in the early 90’s. So Only Trovan Chip readers can read Trovan chips (that was mostly use in the animal ID’s in the US, UK and Australia) but ISO readers can only read ISO. The ISO are mostly used everywhere ells in the world. So there is no open source or tinker board that will read Trovan chips :( that I could find! In My quest to read the chips and take weights without physical catching the animals and add stress and risk their well-being I did manage to find a few very good boards and tools. My favored board (unfortunately stand alone) is the Low cost Animal tag and RFID Reader Writer module with External Antenna. priority1design.com.au/products.html . I did communicate with the designer and he is adding a 5v high pin each time a chip is read so it can be used as a trigger with an arduino to trigger addition functions like registering a weight or trigger a camera. There is an free rfid application program available (priority1design.com.au/download.php?f=rfid_reader.zip) for the board with a nice feature that will check the antenna frequency and allow you to fine tune the antenna for better performance or to adjust the frequency. I am currently exploring the “random” function in Arduino and will like to see a possible future video on that function? My current project; is using the random number generator and relay that to time. This will then trigger a servo in this case that will open a treat box for the animal. This is used in animal enrichment where the animal need to investigate over a period of time the treat box and don’t associate food / treats with their human keepers. This is done in an attempt to reproduce natural behavior where animals spend more time foraging that in a zoo environment where animals tend to associate food with their keepers and know exactly when they will receive food and therefore stop behaving in a natural way. … A bit off topic but will like to see your practical application on the “random” feature. Thank you again for your detailed video’s enjoyed then and find them very practical and useful! Meyer de Kock (Mdk)

@PaulCavanagh69 7 лет назад

there are 3 frequencies 125 kHz, 128 kHz and 134.2 kHz. 125 is mainly USA, and 134 is an EU one. here is info i found on the RFID: www.nerdkits.com/forum/thread/931/ some info on rfid troublwshooting: blog.atlasrfidstore.com/improve-rfid-read-range

@PauliusNORCO 3 года назад

Hello, Ralph. Hope You're doing well in these times! I've been watching Your videos for some time ( i have watched ~50, from the #1 in the series), but didn't do any programming on arduino. Or any programming, to be precise. Had a little issue with Your sketch and been writing a long message about it, but managed to resolve it on the way. Silly issue that was. Sooo.. I guess, i'm here now just to say hi and thank You a lot for all of the work, You put in those videos!

@RalphBacon 3 года назад

Wow, thanks! But you are well behind if you have watched "only" 50 videos as there now about 210 of them! I'm hoping that I can say they get better as you move up the numbers. In these days of house arrest (sorry, lockdown) what better way to spend your time than watching my videos!

@PauliusNORCO 3 года назад

@@RalphBacon Have many ideas for projects and basically no skill, so right timing to learn! Here, in Lithuania, we're also on pretty strict lockdown.. Will be in touch sooner or later! Have a nice evening, Ralph!

@csongorvarga 6 лет назад

I am also using Nick Gammon's library, and I was wondering if anyone tried to use a skinnier font to fit more text on the display. Did you try that?

@RalphBacon 6 лет назад

I can't say I have tried a narrower font, Csongor. But later this year, when I fit my metre long display into my new workshop I may experiment a bit more.

@csongorvarga 6 лет назад

Thanks, that is one more reason to sub :)

@Ed19601 6 лет назад

Great info.

@RalphBacon 6 лет назад

Glad you liked it Ed. I have a monster scrolling display, consisting of about 6 (or is it 7) 4-in-1 displays. It can display messages I send it and also info from RU-vid but I haven't progressed it further. I want to be able to display Google Calendar events but I'm still reading up about the APIs I need to do this.

@Ed19601 6 лет назад

Ralph S Bacon sounds ambitious :-) looking forward to video

@binarybox.binarybox 3 года назад

I've built a lot of scrolling message displays using several different libraries and different hardware eg ICSTATION and FC-16 pcbs and I have many 8x8 display units...so I thought I would look into why some stick up more than others. Looking @ 13' 24" you will see that the ones which stick up more than others have a prefix LD- ...plus other markings as well from other manufacturers. Looking at a short lead and a long lead , you will see the difference in lead length.

@RalphBacon 3 года назад

So the lesson is to buy ALL the modules in one go from one supplier with a message that he must not mix and match from his stock! Good info BinaryBox, thanks for letting me know.

@avejst 6 лет назад

Thanks for sharing :-)

@RalphBacon 6 лет назад

You're most welcome Asger, amazing what can be done with a simple Arduino!

@PaulCavanagh69 7 лет назад

Here's another one for you, hook up a Real Time Clock, then on specific days it would display messages, such as Happy New Year, happy easter, Happy Birthday Benny! or Happy Birthday Ralph!

@RalphBacon 7 лет назад

Too much coding / maintaining a database that one, Paul. Yes, it could be done but someone (me) would have to input all the birthdays and special events. Better to read it off the Google Calendar if that is possible.

@jordanwilson2281 6 лет назад

Hi Ralph I'm a new sub to your channel, first video I have watched and absolutely love the in depth detail. I'm not a programmer but your explanations are great! Do you plan on doing an update for this with the meter long matrix? I have been asked by many friends to make these for them and I'm interested to know how it turned out. Thanks

@RalphBacon 6 лет назад

I did indeed make my metre long matrix, Jordan, tested it and then put it to one side whilst I found a home for it. Now, my workshop is moving so I will wait until that is complete before mounting it. I hope to at least link it to Google Calendar so it can display my reminders and appointments for the day or week. But, I suspect it will be the summer (in the UK) before this is complete - but keep tuned. Just one point to remember is that a matrix this long takes a lot of current; it's best to supply the current at strategic points along the route rather than just at the start, so the tracks don't get overloaded. And, of course, it must be supplied by a separate power supply but thankfully a standard phone charger capable of delivering 2A will be ideal. Glad you like the channel, nice to have to aboard! Thanks for posting.

@jordanwilson2281 6 лет назад

Ralph that's great! Thank you for the fast reply, I am just starting out with arduinos but I think with the tips I have gathered from yourself and video I will be having a go at this myself over the next few weeks. Im now receiving all notifications from your channel and look forward to many more projects if this one goes accordingly. Keep up the good work! And thanks again for the advice

@RalphBacon 6 лет назад

Good luck with your project, jordan wilson and thanks for posting.

@JMParsell 7 лет назад

Thank you for all the great videos! Would you mind doing some videos on the STM32 "maple" boards? There is very little about them on RU-vid and I want to learn more about programming them with Arduino IDE.

@RalphBacon 7 лет назад

Hey JMParsell, welcome. I will add your welcome suggestion to my list as I'm not familiar with the maple boards - keep tuned in case something turns up in a future video, oK? I'll call you "Jay" from now on though, as it's either that or Mr/Ms Parsell which sounds a bit formal, and Jay could be either male or female. And it's a nice MIB reminder too. Thanks for the suggestion, J. :)

@JMParsell 7 лет назад

Jay will be just fine. Thanks!

@george8bitsworth 6 лет назад

It's been a while since I've left you a comment but I just watched this video and found it very informative. One thing I am curious about is why the bit-banged SPI library was needed. Why wouldn't the regular SPI library work? I'd like to mention, that it was sometime in the early '80s I saw a few similar displays made with discrete 3 mm LED's that displayed news and weather I remember that they were 7 LED's high and possibly 50 LED's wise--using a 5x7 matrix for each character.

@RalphBacon 6 лет назад

Hey, captxrox, good to hear from you again. Regarding why I used the bit-banging SPI library, frankly I don't remember, and I regret I haven't the time to look back on that code right now (see ralphbacon.blog for the reason). But the standard SPI library should work too, as far as I know. Yes, the old "ticker tape" displays of the 80's were, of course, all made from discrete components, I don't think I'd have the patience to solder all those LEDs in! Thanks for posting.

@mohunujoodha7155 5 лет назад

Hi there. I'm presently working to code the Max7219 4in1 to display Humidity, Temperature, Dewpoint Temperature and Heat index as scroll text. Anyone has tried it yet. I'm new to Arduino coding. I already hae my codes getting my readings from a DHT11 sensor but wonder how to include that in the Max7219_BitBanged_Scroller codes. Any hint!

@RalphBacon 5 лет назад

Have a look at my video #25, Mohun, that might give you some ideas.

@tomgeorge3726 7 лет назад

Hi Ralph, the RFID unit, have you tried a 100uF capacitor at the power supply input the the reader unit, they do load up with a transmission current spike to initially power the tag. Tom..

@RalphBacon 7 лет назад

Ah, you're referring to the 125kHz RFID reader module, is that right Tom? (I'm only querying because your post is in my MAX7219 scrolling text video). I can't remember what I tried (I did try an awful lot of things) but I'll add this to the list of things to (re-) try when I next dig it out of the components box. Thanks for the suggestion (and do correct me if I have the wrong end of the stick).

@tomgeorge3726 7 лет назад

You have the right end Ralph, you did a little intro to the RFID before going to the scrolling text.

@alanpowell328 7 лет назад

Hi Ralph, I built the above project including the nano with the very useful prototyping base board and it works absolutely fine, currently with 16 digits - and an additional 5 V PSU. However, when I wired it up with my originally hardwired MAX7219 matrices, which appear similar to yours - pins top and bottom, the text was sideways on. I had to disassemble the unit and rotate the digits so that the pins on each board were adjacent - a much simpler wiring arrangement. No idea why, I recall that whichever library I used previously required the top and bottom arrangement - so a bonus feature of the new libraries. Regards Alan Oh - at one point I forgot that there was a movement detector and spent a few minutes wondering why the display was intermittent :-)

@RalphBacon 7 лет назад

Absolutely, Alan, the new library (from Nick Gammon) allows use of the LED matrices side-by-side without all that wire everywhere. I'm sure he did the original library for the top-and-tail version but as I have not even looked I don't know. Glad you got it all working though (even if you forgot about the movement detector! - which incidentally I will amend to stop the program running as well as displaying, so the display resumes [is visible] at exactly the same point at which it went dark). Thanks for lettings us know your success story!

@alanpowell328 7 лет назад

Hi Ralph, The prototype case was finished today and just waiting for some red gel sheets to arrive from China before the enclosure is complete. However, life is full of interesting stuff - I am using a very large 20 Amp Switched Mode 5V PSU, which I purchased for Christmas lights (LED) as the supply, which has started messing with the other hardware. There was a "here we go again" moment when I saw this but it is an issue with electrical noise from the PSU affecting the Arduino Nano when it is also powered from the PSU. When the nano is powered from the PC or a battery and the matrices are powered from the PSU, the problem mostly goes away. I will use another PSU or a 5v pack and the Mother of all smoothing capacitors on the finished item but it is worthy of note because Arduinites in the same situation might blame the matrices or the Arduino. A beefy USB power pack should suffice for portable use. I also have some 8x8 matrix kits from ElectroDragon and while they sort of work, the text is backwards and seriously mixed up - I suspect a tweak in the library will fix that but obviously with such a range of parts available online it is clear that one 8x8 MAX7219 module can be quite different from another. Kind Regards Alan

@RalphBacon 7 лет назад

Glad to hear that you have a working project and have discovered that some PSUs are very noisy indeed. It's normally fairly straightforward to clean it up (a couple of resistors and a capacitor or two can work wonders) - or, as you say, a better 5V supply! The 8x8 LED matrix modules can be wired up in a number of different ways so I expect that the ElectroDragon units are wired differently to what the library expects. So yes, change the library so it knows the orientation of the LED unit and all should be well - but I don't envy you that task. Alternatively try out one of the different libraries suggested here by other viewers, it could save a lot of effort.

@alanpowell328 7 лет назад

Hi Ralph, The hardware differences can be resolved in the Parola library with a utility called MD_MAX72xx_HW_Mapper. This can be found at github.com/MajicDesigns/MD_MAX72XX/tree/master/examples. This allows you to determine what alterations need to be made in the library header file. I think Parola is going to be the way ahead because it appears very versatile. Kind Regards Alan

@RalphBacon 7 лет назад

Although I haven't (yet) used that library I have taken a sneak peek and it looks very versatile. I like the fact that you can have "zones" and scroll up/down too. I'll try it out with my 7 x 4-in-1 display project. Thanks for the link Alan.

@joseluischuraalarcon9928 7 лет назад

Hi! I like so much your videos, but I have a question: what's the name of the software that you're using to program in arduino? because I find the arduino's IDE so basic. Thanks you for your videos!! :)

@RalphBacon 7 лет назад

Hello Jose! I'm glad you like my videos and I hope you find them interesting too. My IDE is the Eclipse IDE and you can find details in the Discussion tab on my channel page (ru-vid.com/show-UC8Ob-HnnmhlgSv5Vs_i32TQdiscussion) as many people have asked this before. However, you might also like the Sublime Text Editor IDE, that is a great step forward from the standard IDE but not as complicated as the Eclipse. Have a look at video #69 Alternative IDE - it may be just what you need.

@joseluischuraalarcon9928 7 лет назад

Ralph S Bacon thanks for your quick reply, I'll take a look to that video :) I have one more question, On the Eclipse software, is possible to use the same programming language that in the arduino's software? (sorry for my bad english) And thanks again for helping me with my questions.

@RalphBacon 7 лет назад

Con mucho gusto Jose! No es un problema! (Sorry for my bad Spanish!) Eclipse uses C++ just the same as the Arduino but it is more difficult to use and sometimes sketches that work on the Arduino do not work (without modification) on the Eclipse. That is why I suggested the Sublime Text Editor, uses the same C++ language and is easier to use. Why not try it first?

@joseluischuraalarcon9928 7 лет назад

Ralph S Bacon Ok, thanks again, I'll try with Sublime text first. Regards from Spain :)

@PaulCavanagh69 7 лет назад

you could hook up an RFID tag reader so that when you use different fob tags it will change the messages to a predefined one. Something like "Happy Birthday", "Merry Christmas" etc.

@RalphBacon 7 лет назад

It never ceases to amaze me. Paul, how you guys have all these amazing idea floating around. Lateral thinking is obviously required these days. I shall get Benny to think long and hard about what he intends to do... :)

@PaulCavanagh69 7 лет назад

thats me! always thinking outside the box :)

@ismzaxxon 7 лет назад

Has anyone got these libraries to work? I have been using Arduino for a while and i know how to load libraries. I even put a copy in the ino folder and i keep getting a message saying bitBangISP.h can not be found. maybe the mod to get it working on another compiler has broken the arduino version....just guessing.

@RalphBacon 7 лет назад

Well, Terry, it all works fine for me (as my demo proves) so let's see what the problem can be. At the risk of teaching my grandmother to suck eggs, are you running on an Arduino Uno / Nano? You have a typo in the library name and I'm hoping it's just here you mistyped it (it should be SPI not ISP). Libraries should be placed in the "libraries" folder found in within the Arduino sketch folder. Libraries should be enclosed in angle brackets. Are you using the (nick Gammon) version I included in my Github repository? Let me know...

@ismzaxxon 7 лет назад

Thank you for the advice. I will delete all files andbstart from scratch. one of the frustrating things with Arduino, compared to my other language compulers, is order of presidence with where libraries area stored. I would rather keep specific libraries with the ino file, otherwise an undate can cause my oyher sketches to stoo working.. I am also using a standard 8x8 display (x2) and not the 4 in one module. in the ino file the pin allocation is not the same as another document...i wilk re-read all and start again. Cheers.

@RalphBacon 7 лет назад

You *can* keep your libraries in the same folder as your sketch and then refer to the library using quotes, not angle brackets/chevrons. But, it does mean you might be holding multiple copies of the *same* library and would you know which version is being used by each sketch? Could take some management, although a simple readme file in each folder could keep the version number etc. Anyway, good luck, and let us know how you get on.

@fabrice26306 7 лет назад

Hi Ralph.... first time I hear my name on you tube haha. Well, nice that you made a new vid about those 4 in 1 matrix, great work!Have you seen he 'hidden' signs / symbols or however they are called? Just try this myDisplay.sendString (18); for example, change 18 by any number to see other graphics, or make a loop from 0 to 1000 to see them all.And Oh, btw, I'm a 'he' !

@RalphBacon 7 лет назад

Hey Fabrice, great to hear from you again! I use the "degree" symbol (for temperature) but the method of constructing the output message string is a bit fiddly (my final demo sketch shows an example). Looping through the symbols in the way you suggest is a great idea to see all the available glyphs. Finally, I sort of guessed you were a "he" (as 95% of my viewers are) but I didn't want to alienate you if you were one of the few female viewers! Great post.

@fabrice26306 7 лет назад

Hi, ... about creating the data for custom graphics.. you will surely be interested in this: github.com/bernhard-hofmann/LedByteGenerator it's a graphical byte generator for 8x8 LED matrix. I still need to experiment with it but it's working, just run de index.html and start drawing.

@RalphBacon 7 лет назад

You have so much information to share, it's great. I'll take a look soon, perhaps over the Easter break when I might have more time. Generating patterns onto LEDs is always time consuming (which I know from my 3x3x3 cube) so anything that speeds this up is a Good Thing. Thanks so much for sharing.

@fabrice26306 7 лет назад

I also have a small program that creates the code out of a graphic which is even much more convenient, but it's not online (at least I don't know where to find it online), I can send it by email if you like. The name is "PixelToMatrix". I wish me too had more time to be busy with this, at this moment I'm mainly interested in LEDs, WS2812B and wireless data transmission.

@PaulCavanagh69 7 лет назад

You could also use a GSM or Bluetooth module to control the text content.

@RalphBacon 7 лет назад

Yes, I could do that. I'm not quite sure what I'm going to do at this minute but I will definitely show you all what I eventually come up with, that's for sure! It will probably evolve over several months too.

@artbecker5618 7 лет назад

Thank you

@RalphBacon 7 лет назад

You're welcome, Art, I hope you found it useful. The 5-sets of the 4-in-1 modules that I ordered have just arrived (from a UK mailbox) so I don't know how I could order from China but get them locally - whatever the reason it means I can build my mega-scrolling display over the Easter break, woo hoo! Thanks for posting, Art.

@artbecker5618 7 лет назад

The Chinese have warehouses in the UK, Russia, and maybe the USA. I am only 3 hours away from them by air, but my shipping takes from two weeks to a month. Then customs can take from one day to four months. AliExpress owns part of SingPost (Singapore's post office), so they ship everything there first, by boat, then put it in the mail to go halfway back to China, by air, in order to get to me. China subsidizes postage for its merchants, but even then they can save a few cents by shipping via Singapore instead. China Post registered airmail is on a space available basis, so packages can sit for a couple weeks before there's room on a plane. The only quick and reliable method is by Hong Kong Post, where they pay an exporter to ship across the "border" to HK in order to drop things in the mail.

@RalphBacon 7 лет назад

That sounds very convoluted Art, the lengths the sellers will go to, in order to save 2c on an item! But it does explain why things can take variable amounts of time from China - I've had stuff after 2 weeks (very occasionally) and also after 8 weeks (at which point the seller had already refunded me but I told him it had arrived and repaid him the refund!). Oh well, as long as the stuff gets to me reliably - and is cheap, that's the main thing. Thanks for that info Art, I bet others will read that and scratch their heads in amazement.

@artbecker5618 7 лет назад

Maybe one package in 25 or so will be shipped from Malaysia. Whenever they say shipped by AliExpress standard method, or something like that , it is usually free, but it will be very slow, and go via Singapore (China to Singapore is by boat, even if you have paid for "air mail"). Hong Kong Post is best, and China Post is next best. Never ever ship by any of the express carriers, like DHL. DHL always, without exception, will charge you 20% of the cost of the order for customs fees. Whether they actually pay those fees to the appropriate government is questionable -- I tend to think that a lot of that ends up in their own pocket. Shipping by any kind of mail usually ends up with little to no customs duty. Shipping by express carrier always means a 20% customs charge. And in many cases, even if you pay a large shipping fee for air mail, your package will still go by boat to Singapore first. Just look at the package and see from which country the postage is paid. Like you said, cheap also means slow, and I can live with that. The exact same thing on eBay can cost several times more than buying directly from China, even if it turns out to be the same seller, in both cases.

@RalphBacon 7 лет назад

Totally with you on this one Art. I buy stuff cheap because otherwise I could not continue my hobby, so waiting 4 weeks (on average) is an acceptable price to pay for me. The only problem is that by the time the stuff arrives I can't remember what it was I going to do with it but that is undoubtedly a more age-related problem! Hah!

@aminedegdougui3486 3 года назад

Can you help me please, i need to display Arabic text with parola....

@RalphBacon 3 года назад

I'm afraid I can't help in doing this but I do know that you can set the text direction from left-to-right to right-to-left which might help you.

@roberteliassen5020 7 лет назад

Great video again, Ralph! Thanks! Too bad the RFID didn't work. I have one or two of these deveces myself (still in their plastic bag).

@RalphBacon 7 лет назад

Well, Robert, it would be unfair to say "it didn't work (at all)" but it would be fair (as my video showed) that it didn't work very well. But I'm still wondering if I've not done something that might make it work better... I'll try again one day in the future (or perhaps you will have better luck?) Nice to hear from you again, BTW.

@andreweastland9634 7 лет назад

Ralph S Bacon I think from the video that you have used a single turn of thickish copper for the coil. That is probably the problem, you need many turns of very thin wire to form the coil like you can see in the picture on the sellers page then it will be much more sensitive.

@RalphBacon 7 лет назад

It most certainly *does* look like one thick turn of wire in the video but it actually is several turns. I didn't do a proper closeup in my video (because, as you probably guessed, I was bit "disappointed" it worked so poorly). That said, it might well be the coil that is not particularly matched to the unit, so I will check the manufacturer's spec sheet next time I dig it out of my box of parts. Great suggestion, thanks for posting.

@roberteliassen5020 7 лет назад

According to the datasheet, at 125kHz the coil should be 21.9 mH. I wouldn't even try to calculate that. Square air coil, how many turns? Do we have a formula for calculating square (or rather rectangular) air coils?

@andreweastland9634 7 лет назад

Do you have an lcr Meter? it would be interesting to measure the existing coil and also to build one with the correct inductance and compare that.

@alanpowell328 7 лет назад

Hi Ralph, DeJa Vu - I built a 12 digit scrolling display last November with a view to doing a bi-lingual Christmas message but bumped into the more than 4 digits doesn't work problem. I initially though it was a hardware PSU issue and also tried every library out there - except Nick Gammon's Doh! In the end I moved on to something else. I was looking at it yesterday and thinking of having another go................... Regards Alan

@RalphBacon 7 лет назад

Hello again, Alan! Did you have the four-in-one displays or the single units? I have a nagging feeling that although I got the Hobby Components library working OK for the individual units, Nick Gammon's code might well work for the individual units too as he has methods in the class that DON'T turn the character 90-degrees (required for the 4-in-1). You might want to inspect that library and see what it offers! (And let us all know, of course, if you have the time).

@RalphBacon 7 лет назад

Hi Alan! Fellow poster squalazzo posted above a very interesting couple of links. Check out the video demo then look at the library, could be just what you want? I will have a look soon too.

@alanpowell328 7 лет назад

As part of my desperate search for a working system, I built a very basic Parola setup but, by that time Christmas and New Year had passed, the urgency to make a sign was less and I moved on to other stuff :-) although one of my Arduino Unos still has the bag of parts with it to build the Parola shield. Looking forward to your take on it.

@alanpowell328 7 лет назад

I don't know what happened to my original reply - must have made a mess of it - Ho Hum. I had the original units with wire top and bottom, and hardwired a 12 digit display. My friend has a CNC machine so we have a frame planned. I've got some of the newer modules still in the packaging - time for a project re-visit.

@RalphBacon 7 лет назад

Definitely worth revisiting. Whilst the older units worked fine (to a point) the fact that the orientation was a bit cockamaney really didn't help. But you can still use those with that HC library or try the newer one that squalazzo found (which I intend to investigate more fully). The new 4-in-ones are just brilliant, my five have arrived now so over the Easter break I'll be constructing it on a backing board etc. I also want to get a continuous strip of red acrylic or similar to face the displays with (like in the demo but stiffer/thicker material). Should be a very compact display with minimal wiring.

@1988palash 6 лет назад

Hi sir am facing a problem with my led display7219 module....actually it's scroll text opposite direction.....so can u help me to fix this problem...........am waiting for ur answar....

@RalphBacon 6 лет назад

Hey Palash, let me think. Is the text being displayed the correct way up. In other words, you have orientated the display the correct way round? The cables enter from the left and the digit 1 is on the far right? So if we display 01234567 the number 7 is on digit position 1, far right?

@1988palash 6 лет назад

sir am purchase this modele.pls follow the link for image on ebay... MAX7219-Dot-LED-Matrix-MCU-Control-LED-Display-Module-for-Arduino-Raspberry. when i connect the cable & power up its like a mirror image....whole things are going opposite direction......pls help me for solution.........its make's me confused......

@RalphBacon 6 лет назад

Is the text displaying correctly or is that backwards, in another words is a "b" shown as a "b" or as a "d"?

@1988palash 6 лет назад

yes "b" is look like "d"..........

@RalphBacon 6 лет назад

First thing to check is whether the polarity of your Matrix display is standard. Put the wires from the Arduino to the OTHER end of the display (normally they go to the left end, and further matrix displays are daisy chained onto the right end) but in this case we'll connect the wires to the RIGHT end and see what happens.

@PaulCavanagh69 7 лет назад

one more, using your pir as a trigger it would randomly display a quote from a list in the sketch each time.

@RalphBacon 7 лет назад

Note enough value that one. I did once design a web system that displayed a deep, meaningful quote of the day, quite unobtrusively at the top of the page. Went down a storm! But guess who had to type in all those quotes (Benny was not with us at that time, so yes, muggins here!). OK, enough suggestions now Paul, but I appreciate your enthusiasm and contributions! Let's wait and see what I come up with...

@PaulCavanagh69 7 лет назад

Another one, connect the display to the internet so that it could receive 'quotes of the day' and display them.

@RalphBacon 7 лет назад

One thing I have already tested is connecting to Google and getting my RU-vid subscription and views count! Now that works (which is not something I'd want showing that often) I wonder what other APIs Google exposes for users... Perhaps I had better Google the Google APIs.

@alanpowell328 7 лет назад

So I was just putting the final touches on my 16 digit scrolling display using plug-in modules for power and Arduino etc. Switched on and immediately realised that I had excluded the 5v 5A Buck regulator, connecting the LED arrays and everything else directly to 19v DC.........................Ho Hum! Smoked 12 out of 16 LED arrays but the Nano survived. Back to the drawing board, well eBay anyway.

@RalphBacon 7 лет назад

OH NO! Frankly it would have been cheaper if the LEDs had survived and the Nano had bought it. Oh dear, I feel your pain and anguish. But eBay thanks you, I'm sure. And I will be VERY careful as I connect my lot up!

@jstro-hobbytech 3 года назад

They cost over 30 dollars for the 4 strips in Canada.

@RalphBacon 3 года назад

That's why I bought mine from China - but you need to ensure you buy all the same plug in modules or the heights can vary.

@electronicsideas1361 2 года назад

error

@RalphBacon 2 года назад

What is the error message you're getting? Did you install the library correctly?

@andreweastland9634 7 лет назад

Hi Ralph, I installed your lib, thanks for the great work you have done on this. I originally wrote my own smooth scrolling lib but it's not a sophisticated as yours. I think you have a small problem with your lib though, I can compile the first two example sketches which load and work fine as is, but when I compile the smooth_scrolling example I get the following error (below). It looks like your sendSmooth function is expecting an unsigned char pointer but you have defined message in the sketch as a signed char. It can be fixed in the sketch code by simply casting message to an unsigned char* but it would be better if it was fixed in your library. Error message.- Arduino: 1.8.1 (Windows 7), Board: "NodeMCU 1.0 (ESP-12E Module), 80 MHz, 115200, 4M (3M SPIFFS)" V:\Arduino\Projects\libraries\MAX7219_Dot_Matrix\examples\Smooth_Scrolling\Smooth_Scrolling.ino: In function 'void updateDisplay()': Smooth_Scrolling:28: error: invalid conversion from 'const char*' to 'const unsigned char*' [-fpermissive] display.sendSmooth (message, messageOffset); ^ In file included from V:\Arduino\Projects\libraries\MAX7219_Dot_Matrix\examples\Smooth_Scrolling\Smooth_Scrolling.ino:9:0: V:\Arduino\Projects\libraries\MAX7219_Dot_Matrix/MAX7219_Dot_Matrix.h:52:10: error: initializing argument 1 of 'void MAX7219_Dot_Matrix::sendSmooth(const unsigned char*, int)' [-fpermissive] void sendSmooth (const unsigned char * s, const int pixel); ^ exit status 1 invalid conversion from 'const char*' to 'const unsigned char*' [-fpermissive] This report would have more information with "Show verbose output during compilation" option enabled in File -> Preferences.

@RalphBacon 7 лет назад

Hi Andrew, thanks for the feedback. Are you using the standard Arduino IDE or something like Eclipse? I ask, because when I use Eclipse I often get many more errors flagged than when using Arduino IDE (which means that if you develop a library on Arduino IDE, it works but when you then try and use it on Eclipse [or whatever] it throws a wobbly). TBH unless the compiler detected overflow I would have expected the unsigned/signed problem to be a warning not an error (narrowing warning) but there we are, the vagaries of various compilers! I'll have a look at this and change the version of the library in my GitHub folder. Thanks for posting the details, much appreciated.

@andreweastland9634 7 лет назад

Hi Ralph, This is when using the standard ide. Apart from this issue it all works fine. I have tested it up to 8 segments. You may have noticed that I am using it on an esp8266 module though not on an atmel chip.

@RalphBacon 7 лет назад

Ah ha! That would invoke a different compiler (a different toolchain I would think), so that's why you might be receiving that error (as I said, some compilers are more stringent in their checking than others). As it happens I was considering the use of my ESPduino or D1 or similar for this project (I now have 7 x 4-in-1 strips, I hope the power is OK) so I will check it out. Thanks for the info.

@joeblow2109 6 лет назад

I guess I'm a (Basic stamp) kinda guy..... i can sum-what program those. Cheers

@RalphBacon 6 лет назад

If you can somewhat program a BASIC Stamp then you can certainly program an Arduino (especially if you have nice demo sketch to start you off!). Take the leap!

@mcocker 7 лет назад

It looks like I used this library in the past when I was working with multiple MAX7219 8x8 LED displays connected together: github.com/MajicDesigns/MD_MAX72XX I managed to blow up an UNO by risking connecting four of the four way units together and not using a separate power supply, I had set the brightness levels low so I knew it would be low current draw and was fine but suddenly a glitch caused all the LEDs on every display to come on full brightness, I had the UNO powered by an external supply and so the on board voltage regulator overloaded and think it let a high voltage through to everything else, the displays are okay but that UNO doesn't work any more. I might try removing the regulator some time and see if it works at all after that with 5V in but lesson learnt, use separate power supply direct to LED displays when it is possible to overload :)

@RalphBacon 7 лет назад

Firstly, Matt, thanks for the heads up on another MAX7219 which I will have a look at. Suddenly, (it seems) MAX7219 libraries are crawling out of the woodwork; maybe there are a couple of good ones that work with several modules of any orientation "out of the box". We shall see. Secondly, condolences on the demise of your Arduino Uno. If you power it via the +5v pin does it work? If not, I fear the worst as the +5v pin bypasses the onboard regulator. If the ATMEGA329P is a surface mounted device then a swift and humane burial in the great recycling centre is called for. If it is an older style Arduino / Genuino with an actual DIL chip then you can easily replace that for a couple of dollars. And quite right to reiterate my message about powering such displays from a *separate* power supply (which can also power the Arduino but not vice versa). You learned the lesson the hard way, maybe others reading this will be forewarned and learn from your miscalculation. Thanks for posting that information, greatly appreciated.

@mcocker 7 лет назад

If I remember right, the MD_MAX72XX library have settings so you can configure orientation and layout so was good for handling the many different boards, the library even has pictures of a few different boards and has a documentation folder, I quite like the MD_ libraries for the reasons they have documentation, tend to be highly configurable and are occasionally updated. As for the poorly Uno, I knew better before doing it since I used to be an Electronics Engineer, now a programmer so like the Arduino for being the bridge between the two, I knew very well what current it needed as a max (no pun intended) but thought "oh I'll just set the brightness setting low and all will be fine" which it was until something triggered them all to come on max by default. The last time I looked at the board I was powering over USB but the 5V was being pulled down to around 3V (btw it is definitely a 5V board and not a 3.3V) so one thought is that the voltage regulator might have failed into a state where the output if faulty and since the 5V would see the regulator output that might be the issue, would be proved by removing the regulator, or in worst case something else past that point is fried. It was a surface mount ATMEGA329P and wasn't an original so not easy to swap and not a huge loss, I always have a few boards in case of failures either from the quality or from my experimentation ;)

@rohansahare7415 7 лет назад

hi ralph

@RalphBacon 7 лет назад

Hi Greeky! I hope you're finding the Arduino-related videos useful on this channel. See you around!

@joeblow2109 6 лет назад

Hi Ralph, most of us are not programmers so be gentle;)

@RalphBacon 6 лет назад

I'll do my very best to be (more) gently in the future, Joe. It's easy (too easy) to gloss over things that non-coders find a brick wall. Point taken. Thanks (again) for the nudge.