Building an outdoor scoreboard..

The Dot Matrix Display (DMD) is a 32x16 array of high-brightness LEDs for visually striking effects. [Product Page]
joevpt
Posts: 6
Joined: Fri Sep 21, 2012 10:31 pm

Building an outdoor scoreboard..

Post by joevpt » Fri Sep 21, 2012 11:03 pm

[ UPDATE October 2014:



After using the prototype for 12 months, and tweaking the software to make the most used options easily available, I built a 'production' model earlier this year. The new score board ( I will post pics later ) is built on a 2400mm x 1200mm backboard and enclosed in a PVC window with a polycarbonate front - makes it weather proof. The board now uses 6 arduino boards - one is a master controller which has either a radio daughter board or an ethernet daughter board and is used to communicate with the board. The others all connect on i2c to the master, and they control one piece of the scoreboard ( 5xDMD for home team, 5xDMD for away team, 4xDMD for home score, 4xDMD for away score and 6xDMD for the clock). ( Thats a total of 24 DMDs for the scoreboard - which is why I need so many arduinos to drive it.)

I have two options to control the board.

Originally I built a remote control using the Hope RM12B transceiver (Jeelib have the library). This gives a range of about 130m and I get about two weeks of continuous running from a set of batteries ( an always on LCD on the remote is the power thief) but I use rechargable batteries ( Of course there is no need to leave the RC on at all if not using the scoreboard, so an on/off switch would extend the useful life of the batteries to a couple of months easily). This Hope board sends serial data so is easy to use and its easy to make control messages such as ResetClock(), or ZeroScore(), or displayScore(20,03), or allLedsOn() etc which are short messages but sufficient to control something like a scoreboard. Don't forget to put some test functions on your controller to show all leds on ( to find if any pixels have failed ) and others to display messages from the radio ( for debugging purposes ).

I have an iPhone App called Rugbyscores which I use to track the score and scorers, which can tweet the scores, email them and post them to a website ( the website needs a script to process and display the posting ). I modified the App to also control the scoreboard. This is much cooler, and as the underlying control uses a webpage on the master controller, it is possible to access the interface using any browser once you can access the WiFi network I have included in the board.

To answer some of the questions people ask regularly. I use a 40A 5V power supply. There are lots of these available on the market. I have powered 9 panels from a single supply, and have had no 'hot' supplies. Of course, my DMDs use a very large font ( characters are 30x20 approx) but many pixels are off most of the time. The longest I have had to use the board is about 6 hours ( three games one after the other ) and all three power supplies were running pretty cool.

Pixel failure is not something I have had a lot of problems with. Altogether I've had maybe six pixels fail and all of these were due to dry joints ( touch up with an iron and they work again ). Because of the enclosure I have built, I do not have water damage, but I do have a small 30W panel heater in the unit, as it is out in the weather and dampness would be my biggest worry. So far, no signs of any damage.

I used just one row of 5 panels for each team name. For a rugby pitch, this is too small. If I had the space I think two rows of 6 panels would be perfect. This would be too many panels for a single arduino, so I would need to split the font across two fonts to make it work.

I use two rows of two panels for each score. For Rugby this is perfect, and is clearly visible around the ground. ( This allows me to display up to three digits 30 pixels high with spacing )

I use two rows of three panels for the clock. The clock displays mm:ss and can count up or down from a preset. We let it count up from 0:00 in the first half and from 40:00 in the second half. The same digit font is used for the clock and the scores. The font does not support non digits except for :

To prevent the displays flickering, I do not refresh by clearing and then redrawing. Instead, I clear only the part of the display on which I want to draw a new digit. So on the clock, if the time reads 01:34 and now needs to display 01:35, I clear only the 4 from the display, and draw a five there, leaving the 01:3 alone. This is much easier on the eye..

Hope this helps,

Joe]





I've been reading about( apparently a good first thing to do for any project ), and trying to source ( why build it if you can buy it at a reasonable price) a scoreboard for my local rugby club, and have found almost nothing which could help... until I found these DMD panels.

This summer my son and I have built a range of large ( over 12" tall ) digits and tried using them on bright sunny days, but without exception they failed the magic test - are they clearly visible from the other end of the pitch ( a rugby pitch is 100m long - not counting the in-goal area which is a mininum of 5m at each end of the pitch). The further distance is the diagonal distance from the board position to the viewer which can be up to 140m at our grounds.

We got our hands on a few boards to prototype them, and straight away found two problems. The first is that each board really does take up to 5 amps so paracitic power from a usb port is not a good idea. An external power supply will fix that ( size it for the number of panels you will use).

The second is that the standard DMD library found here assumes that characters are 16 pixels tall and are writen to the board along the length of the board. We fixed this by making a font ( just for digits ), which would display on panel turned 90 degrees ( that is to say, one digit per panel each digit up to 32 leds tall).

We now have the prototype completed, and have tested it at the ground with great success. We used red perspex as a filter in front of the red panel which reduces other visibility issues.

Our display ended up with six panels ( one is missing at the moment as it is not working - but I think a replacement is on the way). The top digits are a countdown timer, the next two digits are the home team score, and the final two digits are the visiting team score. For ease of use, we added a HopeRf module to the board, which allowed us to also have a remote control. The HopeRf board gives a range of at least 100m with an antenna. We used a tactile keypad on the remote and a 2x16 character display. The keypad allows us to customise the button labels, so we assigned the '1' key to be a home-team try, the '4' key to be a home-team conversion, and the '7' key to be a home team kick (penalty or drop kick). Keys 3,6 and 9 do the same for the away team. The * transmits the score to the board. The # key is a score undo button.

The message here is that the panels work fine in bright sunshine without any issues. Of course you need to protect the panels from the weather ( I have a club associate working on a stainless steel enclosure - due in three weeks). Visibility is fine up to about 120 meters for digits, as described above. Had a lot of fun deciding what a digit should look like - nieces, nephews, in-laws, and other family members all had opinions on what looks best..

We all agreed that for a two digit score, the best visual effect was achieved when we left a gap between the panels of about 20mm.

For the finished product we have put together a PCB and for the Remote control we ran out of pins on the standard Arduino board, so we used a Mega. For the homemade board, we intend using an ATMega164P. First live match is the week after we get the enclosure, but the prototype has been active now for two weeks and all is fine ( the power supply gets a little warm - but not hot).

I will add some images once I get it installed and once I have replaced the bad panel.
Attachments
Project1.jpg
2400mm x 1200mm scoreboard
Last edited by joevpt on Wed Nov 19, 2014 6:09 pm, edited 2 times in total.

joevpt
Posts: 6
Joined: Fri Sep 21, 2012 10:31 pm

Re: Building an outdoor scoreboard..

Post by joevpt » Tue Oct 02, 2012 11:03 pm

Finally got some time to do this thing... See the images attached. Notice the DMD panel on the left hand side of the scoreboard, included there to give some idea of scale. (Remember a DMD panel is 32cm x 16cm (approx 12.5"x6.25") ).
This scoreboard is easily visible at 150m even in very bright sunlight!
scoreboard.jpg
Click on this to get a bigger view ( I think.. ) and to see what I mean about the size of a panel beside the scoreboard.
The prototype controller was a mess, as they always are, but a bit of care gave me a nice PCB layout.
prototype.jpg
board1.jpg
On the final PCB I added a radio so that I could use a remote control.

I made a couple of mistakes on this project. The first was connecting multiple panels to an arduino without using an external power supply for the panels ( or using something to protect the Arduino output pins ). I sorted that out after I fried the first chip.. Make sure that you have power on the DMD panels before you power up the Arduino.

The second was not using a PWM output pin for control of the nOE (Output enable) pin on the panels. This, I found later would have allowed me to dim the panels, though a small change to a macro in the header file would be needed too). I will modify my PCB for the next rev. to incorporate that change, though I have tested it using the prototype controller.

I haven't had a replacement for the faulty panel, but now that I know much more about how they work, I suspect that the leds themselves are fine, the shift registers are fine, and just the controller chip is damaged. If I must, I will change it...

I added two leds to the controller card. One is a simple keepalive ( on/off every second) so that I know that the board is working. The second pulses where a valid packet is received via the radio.

kandos
Posts: 1
Joined: Wed Nov 07, 2012 10:18 am

Re: Building an outdoor scoreboard..

Post by kandos » Wed Nov 07, 2012 10:24 am

Very cool application. A wiring drawing would be useful if you could post it up. How did you create the custom font?

joevpt
Posts: 6
Joined: Fri Sep 21, 2012 10:31 pm

Re: Building an outdoor scoreboard..

Post by joevpt » Mon Nov 19, 2012 10:59 pm

Hi Kandos,

The downloadable fonts with the DMD give a file format for a font file. I took this and modified it. To do this longhand is pretty tedious because you have to create hex entries for each bunch of leds ( and its not as simple as starting at one pixel and working your way to the end of the line ). In the end I set up a page in a spreadsheet. I set it up to be 16 columns (wide) and 32 rows (high) because I wanted the font to read in that direction. I then fill in the cells I want to be ON and it creates the line of hex I need to include in the font file. For each character, you will end up with four lines of hex. Perhaps I should have set up the excel file to allow for variable width and height fonts, but for the scoreboard that wasn't a concern for me. If you want, I can forward the excel file to you.

Attached is a pdf of the scoreboard drawing. The two connectors are for
1) The DMD (or chain of DMDs)
2) A radio (the one I use is based on the HopeRM12B ).




Joe
Attachments
Schematic.txt
The Schematic (rename to .pdf) - the upload process does not allow PDFs.
(33.65 KiB) Downloaded 601 times

astech
Posts: 3
Joined: Sun Dec 09, 2012 11:29 am

Re: Building an outdoor scoreboard..

Post by astech » Sun Dec 09, 2012 11:49 am

Hi joevpt,
Great project using the DMD. I'm planning on developing a cricket score board but need to work out the power needs of the DMD's first. Hoping you can help. What is the working load of your 6 DMD's? Did you buy or build the PSU for your display? I was thinking about using a 20A PSU from an old computer but have already blown up one trying to have it "run" outside the computer. Have you measured the idle load of a DMD? The quick start quide says the load is 4A to 40A but some other blogs suggest 2.5A per DMD.
Thanks for sharing your project.

Regards

42n8
Posts: 46
Joined: Wed Dec 26, 2012 8:10 pm
Location: Auckland, NZ

Re: Building an outdoor scoreboard..

Post by 42n8 » Thu Dec 27, 2012 10:19 am

Anyone considering tipping one of these on edge should be aware that there will be a change in radiation pattern. The ovoid shaped LED used in these modules provides a wide horizontal viewing angle, typically in the order of 55 degrees from the perpendicular. Thus a viewing angle of 110 degrees.

By contrast , the vertical angle is typically in the order of +/-15 degrees from the perpendicular.

Often it isn't an important issue but when the viewing angle is critical to the application and you have rotated the boards, don't be surprised when the viewing angle isn't what you expected.

Regards

joevpt
Posts: 6
Joined: Fri Sep 21, 2012 10:31 pm

Re: Building an outdoor scoreboard..

Post by joevpt » Fri Jun 07, 2013 5:56 pm

Attached is the spreadsheet I used to help speed up generating the hex patterns for the digits. The example is for a 32x16 pixel digit zero. ( The original extension of the file is.xlsx but I cannot upload that extension type.. Just rename it after you download ).

Joe
Attachments
fontmaker32x16.txt
Generating the hex for a character
(13.47 KiB) Downloaded 403 times

User avatar
stryker
Posts: 252
Joined: Sat Jan 14, 2012 2:44 pm

Re: Building an outdoor scoreboard..

Post by stryker » Sat Jun 08, 2013 7:56 am

Thanks for sharing that spreadsheet Joe. Very much appreciate the work you've put into it.

Cheers ! Geoff

Disc0nect0r
Posts: 3
Joined: Tue Mar 07, 2017 10:33 pm

Re: Building an outdoor scoreboard..

Post by Disc0nect0r » Tue Mar 07, 2017 10:41 pm

Hi Joepvt,

know im digging up an old dinosaur here Im currently in the process of building a scoreboard for my Polocrosse team this looks absolutely great. just wondering if your code is available ? don't want to have to re invent the wheel.

mickot
Posts: 6
Joined: Sun Mar 23, 2014 12:01 pm

Re: Building an outdoor scoreboard..

Post by mickot » Fri Apr 07, 2017 1:40 pm

My code is shared in post viewtopic.php?f=26&t=6632 for what its worth

micko

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