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Electronic Billboard for N Scale Model Railroad
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Electronic Billboard for N Scale Model Railroad

by modeller on Fri Mar 08, 2019 10:53 pm

Hey all - been gone for a few years but recently ordered a box o' parts from Adafruit. What I'm making now is an electronic billboard for the side of the road like you can see nowadays along the highways. I'm using a Nano, an RGB OLED, a real time clock, and a TMP36 temp sensor - because one of the displays sequences will show the real time and temperature! It will be cycling through about ten "ads" for different things like public safety and product ads.

It so happens that the tiny OLED is about the right size for an N scale (1:160) billboard. So far I'm making good progress. After the electronics is nailed down, I'll make it more permanent and I'll have to make a scale billboard stand for the OLED and run the wires down from the top of the layout to the Nano under the table.

Anyway, glad to be back posting and I'll update this project a few more times as it gets finalized.

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Test

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Re: Electronic Billboard for N Scale Model Railroad

by adafruit_support_mike on Sat Mar 09, 2019 4:13 am

Awesome! We'd love to see photos of the billboard once it's in your layout!

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Re: Electronic Billboard for N Scale Model Railroad

by adafruit_support_bill on Sat Mar 09, 2019 7:23 am

Nice!

Note that it s possible to separate the display from the PCB if that is getting in they way of your modeling. They are attached with a bit of double-sided adhesive tape and can be removed with some gentle prying. You will need to use extra care once they are separated since the flex-connector between them is rather delicate.

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Re: Electronic Billboard for N Scale Model Railroad

by Disciple on Sat Mar 09, 2019 2:58 pm

I'm interested in pictures, too. My dad used to collect.
One point you probably already know, if the OLED will be displaying its graphics over the long term, a good idea might be to design those graphics with varying colors and layouts to avoid burning patterns into the grid. I've seen damaged store display TVs where that precaution wasn't taken.

Best of success. I bet we'll see an Adafruit billboard. (c:

Hallelujah!
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Re: Electronic Billboard for N Scale Model Railroad

by modeller on Sat Mar 09, 2019 7:30 pm

adafruit_support_mike wrote:Awesome! We'd love to see photos of the billboard once it's in your layout!

Thanks for the interest Mike, Bill, and Disciple. Just for context I added a shot of the layout. Not sure exactly where the billboard will go yet.

adafruit_support_bill wrote:Nice!

Note that it s possible to separate the display from the PCB if that is getting in they way of your modeling. They are attached with a bit of double-sided adhesive tape and can be removed with some gentle prying. You will need to use extra care once they are separated since the flex-connector between them is rather delicate.


Yea, that's something that might be valuable in some other modelling situation. I think for this one it's probably going to have to stay there because there's no easy way to hide it if "unfolded". I do plan on cutting away the bottom screw holes as far as I can. Then I'll have to design the frame around what's left so that only the main OLED display is showing. I also want to de-solder the header pins (one-by-one) and pull them out, to be replaced with small wires going down to the Nano board.

Disciple wrote:I'm interested in pictures, too. My dad used to collect.
One point you probably already know, if the OLED will be displaying its graphics over the long term, a good idea might be to design those graphics with varying colors and layouts to avoid burning patterns into the grid. I've seen damaged store display TVs where that precaution wasn't taken.


The OLED (well the whole layout) really won't be on all day, only for at most a few hours every so often. But it is something of note that once this model is finished replacing the display will NOT be something that one wants to attempt ... :-)

Best of success. I bet we'll see an Adafruit billboard. (c:


Adafruit on the Billboard? You know that gives me an idea for one of the ads ... stay tuned for it LOL. I'll put a video on You Tube when I get a good set of ads going.
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Re: Electronic Billboard for N Scale Model Railroad

by modeller on Sun Mar 10, 2019 8:31 pm

Ran into an issue. I removed the header pins and attached small wires needed to run to from the top of the layout to the underside. They were two feet long. Now the display will not reliably work. It seems to depend on the way the wires are situated, indicating some sort of coupling between signals. I cut the wiring in half to one foot and it works a little better but still not going to work right.

I didn't expect it to be that sensitive to having the signal wires extended. I suppose I can cut more off but at some point I have to have a length to go under the table.

Any suggestions as to the cause of the problem? I mean the wires were already 6 - 7 inches long coming from the breadboard and it worked OK then ...
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Re: Electronic Billboard for N Scale Model Railroad

by adafruit_support_bill on Mon Mar 11, 2019 6:20 am

Longer wires are going to be more susceptible to noise, crosstalk and other interference. The clock and data pins are probably the most sensitive.

You could try wiring the clock and data lines as twisted pairs to help reject noise. Ethernet cable is a good source for nice tightly twisted pairs. Use one pair for SCK and GND. And use another pair for SDA and GND.

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Re: Electronic Billboard for N Scale Model Railroad

by modeller on Mon Mar 11, 2019 8:29 am

adafruit_support_bill wrote:Longer wires are going to be more susceptible to noise, crosstalk and other interference. The clock and data pins are probably the most sensitive.

You could try wiring the clock and data lines as twisted pairs to help reject noise. Ethernet cable is a good source for nice tightly twisted pairs. Use one pair for SCK and GND. And use another pair for SDA and GND.


Thanks Bill - I just tried twisting the data line with ground and since I had no other ground wire I twisted the clock with CS - now it does work OK. Whew.

I think I'll add one more ground wire to twist with the clock and that should do it.

Thanks.

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Re: Electronic Billboard for N Scale Model Railroad

by modeller on Tue Mar 12, 2019 9:37 pm

Update:

The noise problem has definitely been solved.

Since we just got on daylight savings time I realized (after research) that the real time clock doesn't correct for DST changes natively. I did find numerous software additions that claimed to take care of it which seemed rather complicated, but hey this is not a mission critical system - it's a model railroad.

So, after some considerations I decided to simply add a button switch, an additional LED, and some code that will indicate that DST has been activated. The RTC time is set up to "normal" time (non-DST). All the button does is sense a press, sets a boolean variable, and adds an hour to the displayed time until you want to end DST. The DST true or false variable is stored in eeProm so when powered on it will read the value back and continue to add the hour. When DST is ended in your area you simply go under the table again and press the button until the LED goes off, and the time goes back to "normal" time until the next time DST comes around. Simple and it works.

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Re: Electronic Billboard for N Scale Model Railroad

by adafruit_support_bill on Wed Mar 13, 2019 5:42 am

That is a perfectly reasonable solution. DST is subject to change at the whims of legislators, so software solutions are only good until the rules change

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Re: Electronic Billboard for N Scale Model Railroad

by modeller on Wed Mar 13, 2019 10:39 am

adafruit_support_bill wrote:That is a perfectly reasonable solution. DST is subject to change at the whims of legislators, so software solutions are only good until the rules change


Thanks. The real time clock might be overkill for some people but if it's going to be there might as well do it right.

By the way, here's my tribute to Adafruit which will be one of the ads cycling on the electronic billboard. I would make an Adafruit show room too but if you actually go 10 scale miles you'd fall off the edge of the world LOL.
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Re: Electronic Billboard for N Scale Model Railroad

by adafruit_support_bill on Wed Mar 13, 2019 10:59 am

if you actually go 10 scale miles you'd fall off the edge of the world LOL

Sounds like time to start negotiating ROW with the neighbors. ;)

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Re: Electronic Billboard for N Scale Model Railroad

by modeller on Mon Mar 18, 2019 9:09 pm

I finalized the wiring so I mounted it all together so as to facilitate getting it installed under the layout. I'm now adding familiar company logos using the Adafruit suggested bitmap tool here -

simple tool to change images into byte arrays

Seems to work rather well and after a few tries changing settings with each logo you can get something usable. Need to use logos with no more than two colors, unless you want to resort to full color using other techniques and hardware.

Should have a video of the ad sequences soon.
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Re: Electronic Billboard for N Scale Model Railroad

by modeller on Sat Mar 23, 2019 9:37 pm

The easy part is done, now I have to build a N scale model for it!

Arduino Electronics Billboard

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Re: Electronic Billboard for N Scale Model Railroad

by XRAD on Sat Mar 23, 2019 11:46 pm

Great project!

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