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6th JC Cards (RFID)

6th Joint-US-GE-Cache „Virtual Flight“ (RFID) (GC???) 

My first idea to built a RFID based cache you didn’t liked. But during your stay at the hospital with your friend, you showed me this video on YouTube:

As ever: By clicking the YouTube button, you can watch it in 1080p…

This would be a cache US cachers would like… So I bought some RFID stuff...


… and started with the programming. This one will 100% done by me, no „prototype“ from someone else to be used.

I started with an UNO and after some time I was able to read the RFID code from the chips:

IMG 1250


When adding a 2x16 LCD and 4 LEDs to the hardware I was running out of pins at the Uno, so I rebuilt it with a Mega:

IMG 1254

Step by step I’m working on the sketch.  During all the testing I destroyed again the boot loader of the Mega (SaintSmart clone from China). I just used another one (fine if you have some in your spare part stock). Today I’ll try to reflash it again. 

Unfortunately I’ll be quite busy today, so I fear I won’t have much time to work on it…

During the afternoon I found some time to reflash the boot loader of the Mega. I had to do it twice. After the first reflashing there was still a problem with communication between USB and the board. I did it again and after the 2nd reflash it was a full success!

Maybe I’ll find some few time to work on the sketch later this afternoon…

Update 21.11.2015 - Prototype ready!

Already yesterday I worked on a new design for the cards. Tarot cards are out!


I hope, you’ll like them…

Today I was able to spend some time on our project. There was a hard fight with the timer and also a lot of bugs still inside the sketch. But step by step I did it:

As ever: By clicking the YouTube button, you can watch it in 1080p…

I implemented a special testmode into the sketch. When you’ll set TestMode to -1 the hardware is only showing the RFID codes of the cards you want to use later. So no extra sketch needed for that.

As you can see, I’m using quite small 3mm LEDs, because they need less power.


You can get them from Amazon in the States.

Last not least: Different to the „inspiration cache“ we won’t place batteries inside. The cacher has to bring its own ones. (In Germany I’ll mount the holder of a 9V energy block to the back). Result: No maintenance on the batteries by us AND no power-on key needed…

Also I looked for a box at Not so easy, because some conditions should be met:

  • big enough for all the hardware
  • even when connecting again with USB
  • looking at least a little bit nice
  • the cap shouldn’t be carved totally to be able to place the LCD screen
  • the cap should be deep enough to store all the hardware and can be closed by a thin plate later

I ordered this one:



I hope, the cap will be deep enough…

Update 26.11.2015 - The box...

The box arrived. But 20 cm x 13 cm is much smaller than I expected. I’ll use it for something different. I searched a lot for a larger one. But most of them are having such a size or are even smaller. Now I ordered this one from eBAY:

IMG 1280

IMG 1282

The dimensions are 28,5 x 23 x 14,5 cm and the cap should really be deep enough to put all the electrons inside. 

Just after hitting the buy button I found this one at Amazon:

715Q6ndVrdL. SL1500

IMG 1274

IMG 1277

The dimensions are 30 x 20 x 8 cm. Just by hitting the key again, I’ll have the choice which one to use...

Update 29.11.2015 - Tim working all around the clock...

Yesterday in the evening (at me - noon at you) we did FaceTime again and you were ready to spend time for building your prototype. This morning I received an eMail, saying, you worked up to 11 p.m. and the LCD was still dead. This morning (your time) I became aware that the sketch in DropBox was updated by you. So first thing you did, was to come back to work on the hardware. After some SMS sendings I called you via FaceTime. Really, you’ve sitten there in your pyjama prior visiting the bathroom. After a short discussion I became aware, that there was a bug in my sketch. So I asked you to visit the bathroom while I’m working on that. When you returned, I have been ready and everything worked well.

I was happy to see your big smile on your face prior you and Marsha would be out for church.

Btw: You came up with a great idea for the housing. Instead of the boxes to use a bird house (what a surprise!). But with two fronts. Behind the first front there would be a second one with the LEDs, the LCD and the cards. Very good idea. I’ll wait up you will show me pictures from your prototype.

Update 9.12.2015 - „Cards“ becoming „Virual Flight“

You had the idea instead of making this one a cards game, making it a virtual flight from your Berkeley Country to me. This will be the map on the cache:

The cacher will find 6 boarding passes like this:

Cards Design

Only the seat numbers are different and will give the code at the end. Everytime a correct boarding pass is dropped to the RFID sensor a LED in one of the locations (Berkeley Country, New York, Frankfurt, Tostedt) will shine.

You can pick the full sketch here

©  Olaf Goette 2008 - 2022