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By jbreizh
first of all an french so pardon my speaking and i am new here. I am a french maths teacher, so i not a pro just having fun and learning electronic.
I wanted to put an end of a light painting project i begin 6 month ago (15days of work and the rest of the time resting on my desk...). It's a classical light painting stick using led strip, but base on this old french example ... version-2/ i had the idea :idea: to drive it using a smartphone. So i had a working prototype using :

-my android phone with a custom MIT app inventor app with use bluetooth to send every information to the arduino board. This is the "brain" and the user interface of my project, alowing to choose the picture, resize it, loop an reverse it and set the speed of the picture projection.
-an arduino uno r3 (5volt) with a chinese bluetooth module(3.3V) to drive the led according to the information (each pixel color of the the strip) send syncronously by the smartphone (serial over bluetooth)
-a led strip : ws2812b ; 60 leds for display mount on a custum bracket (aluminum bar with a kitesurf board handle)
-an usb 5v battery bank to power both the arduino and the led.


So i had result and after a bunch of optimisation on the mit app (very slow but i haven't the knowledge to nativ android programmation) I decide that 15ms per frame is the max reliable send and show rate. Faster, there is problem of synchro because of the send time. This is good for me, because my led bar is 1M long for 60 pixel 15ms is 66 frame per second so a show spedd just above 1m per second to keep it square. It's fine because if it s to slow, first you need a very expensive camera witch allow very long aperture and moving slowly without shacking is very difficult.


But i also face unresolve problem : random frame drop or frame miss (watch carefully the result picture you will see it). So after testing a lot of schem i think i find the problem : the WS2812b led. In fact, the combinaison of serial and WS2812d. Apparently, to drive the WS2812 the interruption are ignore during a shore time and the interruption are use by serial. So 6 month ago, i find the solution (using apa102) and .... i drop the project ;)
But now i want to finish it and using it. So i need to buy a small arduino board (i don't care of power it's just receive and drive led) with compatible bluetooth board (normal not low energy as i test it but mit app don't support it) and a 60 led strip APA102 all in 5V (to keep one standard usb battery without 3.3v hack). My goal is to make somethink that work ( :roll: ) without an hackish look (like now). Can you check my order list if i did something wrong :

- arduino board : Arduino Pro Mini 328 - 5V/16MHz 5volt, directly arduino uno compatible?? small
- bluetooth : SparkFun Bluetooth Mate Silver 5 volt, easy to plug, bluetooth "normal"??
- led : LED RGB Strip - Addressable, 5m (APA102) 5 volt, APA102 !!!!

Tell me what do you think of my choice (alternative, incompatibility, wiring problem). Thanks
By jbreizh
Just for laugh, my MIT app inventor block :
It's not exactly the working one, because i made modification test i can't remember before droping the project. I made crazy stuff like sending letter in decimal ascii code, dynamic timer clock ajustement, over complicated imbricated fonction .... in a tool mostly think for kid.
Watching this, I think i was mad... I need to finish this.
long long title how many chars? lets see 123 ok more? yes 60

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