This prototype stems from another project\product to be that I haven't posted about except for this sneak peak: Project Sneak Peak. I noticed that most LED Matrix drivers on the market use shift registers to give a microcontroller the ability to control more LEDs than would be possible. Last year I came across the MAX7219 from Maxim Integrated. This cool little IC does all the work for you to drive a LED Matrix or LED Segment display. It uses a variation of the SPI protocol and can be daisy chained. The other cool feature is you only need 1 resistor to set the max current and therefore the brightness. The best part is there is an Arduino library already.
 |
| MAX7219 LED Driver from Maxim Integrated |
Since I have been playing with this IC and getting to know it I decided to make a carrier board that fits on the back of a 3mm (each LED size) LED Matrix. As seen below, the left is the input side and the right is the output side. The Arduino library lets you daisy chain 8 of these together. If you want more, then you just use a separate set of pins and another instance of the library. I think there is a way to get more than 8 in a row but you might need a buffer or something.
 |
| LED Matrix Link unassembled |
I have a few things to tweak in the design, but I plan on listing these on Tindie if anyone would like to buy them. Depending on the price I can get on the MAX7219 will determine if I need to do a fundraiser or not. They are rather a pricey IC but I would like to get them as cheap as possible as most people will need more than 1.
 |
| Two LED Matrix Link together |
 |
| LED Link Matrix Breadboard |
With the EXT_DIN right angle header (included) you can use this on a breadboard if needed. Otherwise I am working on a microcontroller link. It is the same size and has a Atmega328p. All you have to do is attach it to the EXT_DIN connector. This is great for permanent installation and you don't have to tie up your UNO or other microcontroller. It makes a nice fit for ease of use with the pre-programmed sample sketch.
One of my uses for this is I want to setup 8 of them to display messages during the reception for my upcoming May wedding. Maybe give the ability for guests to send messages to it!
Looks good, that setup with the breadboard is crying out to have Tetris played on it, though :-)
ReplyDeleteVery nicely done mate.
ReplyDeleteI can see how these nifty modules could get useful!
Keep up the great work.
Are you going to make the board layout/project specs freely available? If so, where might I find them?
ReplyDeleteI will once I get the final design. There is a slight alignment issue. I sent out for a revision last night.
DeleteYou can look for it on my github.
http://www.github.com/friedcircuits
Awesome project! I've not find these on Github...could you link it? Thanks
DeleteIts not there yet. I want to fix the gap first before I post them. Should have the updated version in two weeks so I can verify it is right.
DeleteShould get these sold on Sparkfun as a kit. Great design.
DeleteJames
That would awesome! I have been wondering what their process is for new products. I wanted to see if they want to put up the USB Tester. I will have to contact them and see what is up.
DeleteList them on Tindie and I'll buy 8. If you need to do a startup, I'll back it.
ReplyDeleteThanks, I am going to work on getting it listed tonight. I'll do a fundraiser so I can get the MAX7219 at a better price. Then by the time the fundraiser is over I will have the final design ready.
DeleteHere is the link to the Tindie listing. https://www.tindie.com/shops/FriedCircuits/led-matrix-link/
DeleteIn the 2nd paragraph, I think 3mm should be 3cm.
ReplyDeleteOh, I was referring to the size of each LED in the matrix. I should update that.
DeletePssst; search for the MAX7219 on ebay...
ReplyDeleteYeah I could, but I don't want to risk counterfeits. Too many of them around. Read the PIC form.
DeleteDefinitely some sketchy stuff out there. Gotta be careful!
DeleteVery cool. Would be a good add-on for my eventual pinball machine build; Depending on the cost of the board (a few bucks each?) and the driver...digikey 10.49 singles or about 5 bucks each in 100 quantity...That's fairly reasonable. It's still a bit pricey for lager matri'.
ReplyDeleteThanks, I really wanted to cheaper price, but the only way would be from eBay. But I have been reading about a lot of fakes. You can read about it on the PIC forum, so it's not really worth the risk. I may order a few and test one of the sellers on there but some of the fakes works, just not well and you have to have a boot delay for them to work. So they really aren't reliable.
DeleteAlso don't forget the costs of building them, tindie fees, and support.
DeleteLate to the party, and if you sell these in kit form, I could always supply my own etc., but.. have you considered using the square mask matrices? A similar ( in that it's also a 3x3cm matrix project.. that's where the similarity ends ;) ), project, uses them: http://www.arachnidlabs.com/blog/2013/03/15/introducing-minimatrix/
ReplyDeleteI don't know if pinouts differ, but that shouldn't be too horrible to redesign.
I think the pinout is the exactly the same, I will have to double check. I am using common cathode. The LED Matrix Link is a kit as far as the through-hole components. As far as supplying your own do you mean the IC? So the kit would include everything except for the MAX7219? Might cost more for the end user to supply their own IC unless they want to go the eBay route of course.
DeleteNo, sorry, I meant supplying one's own LED matrix module (considerably cheaper than the driver IC!) - be it for the difference in mask as I mentioned, or just different color (assuming any Vf difference would not be an immediate issue).
DeleteNot a bad idea. I could also sell just the PCB. I'll keep it in mind after the fundraiser. I am trying to find other colors, but I realize it is not easy. Red is so plentiful compared to other colors. I would like blue but wow what a price jump.
Deletecheck out http://wiki.niftylight.de if you want to keep the firmware simple and offload work to a bigger platform. It's free & open and has been made exactly for this purpose to serve as middleware for hardware like this and high level GFX software (VLC, gStreamer, SDL applications etc.) including colorspace conversion, pixel mapping and all this nasty stuff you prefer beeing already done. It also serves as platform to combine various types of such hardware in a single setup, so you can integrate it with other LED/lighting stuff.
ReplyDeletePlease don't be afraid of the complexity and the early stage of documentation! :) (We try to give best user support but for now you might want to use the googlegroup mailing list for support since the only active developer currently cares for a sick family member... Or you can idle on IRC if you're patient ;)
There even is a (merely untested) plugin for arduino+MAX7219 drivers already which can be found here: https://github.com/niftylight/niftyled-plugins/tree/master/plugins/arduino-max7219_max7221
Delete