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Topic: Sanity check on project plan (Read 206 times) previous topic - next topic

soonerdave

Greetings, all.


I thought I might post some general ideas for the implementation of a "vintage/retro" model scoreboard project I'm working on, just to see if there might be glaring errors or suggestions in general.

First, this scoreboard is going to be a faithful, working reproduction of an mid-70's/early-80's era college stadium football (American football, that is) scoreboard, with a pretty standard home/visitor score, working countdown clock, and a space for current quarter, time outs left for each side, as well as down, yards to go, and "ball on" indicator.

The score and clock digits will be .8" yellow seven-segment LED's; all remaining digits will be .56" yellow seven-segment LED's. The score and clock will consist of four two-digit LED's; the others will be four single-digit LED's and two double-digit LED's, totalling 8 "large" digits and 8 "smaller" digits.

I plan to drive the LED's with a pair of daisy-chained MAX7219's; one for the smaller LED's, the other for the larger ones. With those drivers handling the multiplexing, the max draw should be at most 100-120mA for each bank of LED's being driven, with the whole schmear hosted on an Arduino Uno.  I plan to wire up a bunch of momentary contact pushbuttons on a separate small console to control the digits through a script in the Uno. So far, that doesn't seem very complex or complicated.


The part I'm not yet sure about are the matrix regions I plan to build for the team name "badges" over their score sections. I plan to use 8 5x7 LED matrix displays in what would become 40x7 display region. I should be able to drive these with two MAX6953's (one per four matrix displays). Since I need two such badges, I'll need four total 6953's to drive 16 5x7 matrix displays. 

My question is whether its realistic to put two MAX7219's *and* the four 6953's off a single Arduino. I'm confident the Uno could handle the two 7219's and the 16 LED's they will drive for the basic scorekeeping, but I'm not at all sure I could push the additional matrix drivers/displays on there as well. I've all-but resigned myself to a dedicated power supply; should I be looking at a second Uno to run the name badges? The intent for the badges is to do nothing more than statically display each team's name; no animation or graphic images; set it once and forget it. 

I may well be overthinking this, and underestimating the Uno, but I thought it more wise to ask than wonder. Apologies if the question is dumb or the answer obvious to the rest of the world; just isn't to me :)


Thanks.

blh64

The MAX6953 chip uses the i2c protocol (e.g. "Wire" library in Arduino) so you just need to connect it up to the Uno SCL/SDA pins (A4/A5).  Since you will be using 2 of these chips, you will have to make them respond to different addresses on the bus by wiring the A0/A1 pins differently (one has both tied to ground, one has one tied high, one to ground)

Paul__B

I am wondering what is so good about the MAX6953s?

Five MAX7219 matrix modules (you can get them in groups of four) would make a 40 by 8 unit, so ten modules would do your matrix displays.  What colour did you want it?


For any practical project, you would be better to use a Nano than a UNO.

soonerdave

I am wondering what is so good about the MAX6953s?

Five MAX7219 matrix modules (you can get them in groups of four) would make a 40 by 8 unit, so ten modules would do your matrix displays.  What colour did you want it?


For any practical project, you would be better to use a Nano than a UNO.
The pre-built 4-by-8x8 were very intriguing and would have been a perfect choice had I been able to find them in a small enough configuration. I found only 1.2" sizes which are too large for my project, and even then none were in yellow.

What makes the Nano preferable/more practical than the Uno? Sorry for the naive question.

Thanks.


wolframore

like this? mini 8x8 LED

0.7" I2C

Found doing a search for "miniature 8x8 Yellow LED"
Bad boys rate our young girls but Violet goes willingly :)
- this is a mnemonic from BEC

soonerdave

Per that link, only four remain. I'd need 10. The closest matches I could find were sold out or were selling at something like $59 each. I found an .8" version, which is really still too large vertically  (.7" is ideal given my constraints) and a proper multiple would be too narrow (4 @0.8" is 3.2") while an oddball 5 is 4" - and that's too wide. My badge region is constrained to .7" x 3.5"

Thanks for the idea, nonetheless!


blh64

What makes the Nano preferable/more practical than the Uno? Sorry for the naive question.
Size.  They both use the AT328 chip.  With the nano, since it uses the SMD version of the chip, you do get A6 and A7 if you need two more analog inputs.

Paul__B

Size is an advantage, but the overall form factor is more practical.  Two straight line of pins with a smaller connector on the end (advisable to re-solder the pads that hold it on with some real solder), generally supplied with the pins not soldered so you can solder your own leads directly, using the pins you can mount it to a solderless breadboard, a "screw shield" or as a daughter board to your own custom PCB.

And generally cheaper.  Yes, it also has the last two Analog pins.  :smiley-cool:

soonerdave

Well, as I've read through these replies (thanks) and done some checking, I've found the 6953's are nearly out of stock everywhere (obsolete) and the places that have them ask $30 each. That'd be $120 for my project. Yikes. For a hobby/fun project, that's getting a little steep. I've got nearly everything else I need for this project, and I don't believe I've spent that much.

Switching to 7219s doesn't help much; I'd need one for each matrix, and even those are a bit scarce. I happen to have to 7219's on hand, but those are already allocated.

Not sure what to do; I don't see many alternatives. I see Adafruit still offers 16x8 "featherwing" backpacks, although I'd have to wire the LED rather than solder it; I need to mount the LEDs side-by-side. Even then, the final dimensions of .8" x 3.2" aren't a very good fit for my project  ☹️. Alas.

Guess I'm going to have to make one of those tradeoffs or leave this part of the project out. If there are better suggestions out there, I'm open to them.

Paul__B

Switching to 7219s doesn't help much; I'd need one for each matrix, and even those are a bit scarce. I happen to have to 7219's on hand, but those are already allocated.
I hope you are not suggesting that MAX7219s are scarce.  :smiley-eek:  The small matrices may be,

soonerdave

I hope you are not suggesting that MAX7219s are scarce.  :smiley-eek:  The small matrices may be,
Nono I was just referring to the fact I'd need one per matrix....going from four 6953's to 14 7219's

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