Bug fix

I've had the LED string attached to a spare Raspberry Pi for a few days and I frequently noticed my home airport, KIPJ, frequently failed to retrieve the weather.

Looking at the code, I saw the LiveSectional program making a request to:

https://www.aviationweather.gov/adds/dataserver_current/httpparam?dataSource=metars&requestType=retrieve&format=xml&mostRecentForEachStation=constraint&hoursBeforeNow=1&stationString=KIPJ

This URL frequently resulted in a truncated METAR string.

I reached out to Aviationweather.gov and they suggested changing "constraint" to "true". I made the appropriate change to /NeoSectional/metar-v4.py, line 545 and the KIPJ LED has been illuminated ever since.

https://www.aviationweather.gov/adds/dataserver_current/httpparam?dataSource=metars&requestType=retrieve&format=xml&mostRecentForEachStation=true&hoursBeforeNow=1&stationString=KIPJ

That's very interesting. When you read the documentation for this service it specifically states that 'constraint' should be used instead of 'true'. Since 'constraint' will only provide data that has been updated within the 'hoursBeforeNow' parameter. So extending this from 1 hour to 3 hours would provide up to 3 hour old data. I assume then that 'true' will provide the latest updated data no matter how old it is. So if timeliness is an issue, 'constraint' would be the more accurate. However, a white led all the time is not very helpful either.

I'll go back and play with that and see what happens. Thanks for pointing that out.

We look forward to your updated on the board. Thanks for doing that. - Mark

PCB Interface Board

I didn't want to permanently mount a breadboard so I designed a small interface board in KiCad. The board has the same dimensions of a Raspberry Pi Zero. I plan on using OSH Park to manufacture the board. At this moment I'm letting the board design "soak" for a few days before ordering, any feedback would be appreciated!

Thanks for this. I have wondered how hard it would take to get a PCB professionally built. I've hand made all mine, and while they work they are not very pretty.

If you don't mine explaining the process a little further, I'd appreciate it. For instance, can you point to information on how to use KiCad and how much it will cost for your board to be made? How long will it take to receive. - Mark

@markyharris

Google is your friend with KiCad and PCB ordering. KiCad is as intuitive as avionics. This series is a decent overview of how to manipulate KiCad.

My KiCad Interface Board (Rev0) project file is available at: https://1drv.ms/u/s!Aop6zsLVPPGDhZ9HWTXWIz8zpTMnpw?e=wGHRPK I invite you to download KiCad and play around!

I forgot to mention turn-time and cost!

https://docs.oshpark.com/services/

For this one-off project, I'm bouncing between the "2oz 0.8mm" and "prototype" services. ~$20 and 2-3 weeks for three nice boards or ~$10 and 12 days for three acceptable boards. For an interface board that no one will see, prototype is likely sufficient.

The Sectional is complete!

I had wanted to use this thread as a build log but ended up running out of steam as I chipped away at this project in little bits of free time over the last month.

I used UPrinting to print the sectional I had modified in GIMP. The poster was attached to MDF using 3M Super 77.

I made the frame from 1"x3", stained dark and applied a few coats of polyurethane.

The interface board turned out really well, I'm quite pleased with it. I crimped my own 0.1" headers on the ribbon cable to aid any future disassembly (where I may not remember all the connection details).

Instead of sacrificing/skipping LEDs behind the board, I chose to cut the string and extend the wires between the LEDs. I utilized JST SM connectors rather than simple wires as interconnects to aid in flexibility and making some on-the-fly decisions easier. These splices took a significant amount of time; however I really did not want to waste LEDs. If I was building this again I would not have purchased a pre-assembled string of LEDs.

That's a wonderful job. I love the interface board. it's so clean. 

I just ordered 3 of them using your file located at https://1drv.ms/u/s!Aop6zsLVPPGDhZ9HWTXWIz8zpTMnpw?e=wGHRPK and it it only cost $15 dollars, that includes the shipping. So it we very reasonable. I used OSH Park to do the printing as you suggested. I should receive them in 5 days.

Thanks again for this. This will really help people building these! - Mark

Awesome Mark! Be advised I have one error in that silkscreen, the label that says "Pin 6" should be "Pin 5" on the Raspberry Pi header.

In my final version, I rotated the SN74AHCT125N 180° and added another 0.1" header on the 5V rail for more flexibility.

BOM from Digikey:

• Power Jack - PJ-202BH
• Power Supply - WSU050-3000-13
• 2x20 pin right angle header (for the Raspberry Pi) - PRPC020DBAN-M71RC
• Level shifter - SN74AHCT125N

@mattzap

I like your idea of making your own pcb board. I can’t tell in your photos. Is that a harness you designed to connect the wires from your pcb to the pi or did you find it somewhere?

@greygoose

I built my own ribbon cable from this kit but I'm positive you can buy a pre-made ribbon cable with individual 0.1" headers for much less expense.