Author Topic: KrystaLED (First PCB Project Help,Comments,Suggestions please) ATTiny&WS2812b  (Read 170 times)

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Offline calli

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Hi,

I am still not sure where to put it. It is just a hobby thing no commercial intents, will be OSHW for sure. But as it is my first project with a PCB I need many suggestions, critics and comments for sure.

I made a little platform (3D printed) which (as for now) includes a digi stumb (Attiny USB plug) a WS2812b and a 9V Battery. See the image.

As little project I decided to try Easy EDA and made "proper" version of it.  Link (tell me if it is not working):https://easyeda.com/carsten.wartmann/KrytaLED-c606fd6f46d342eaa2b26589556419c8

So far I think it could work.  Some more thoughts/questions:

- I made a single and a double sided pcb. The double sided will be more easy to mount.
- mounting is so far thought to be with hot snod. Fast and easy. Screws are a bit delicate at the position on the top of the case
- double sided pcb can be smaller
- the connector is so big so that it is easy to use for flashing and dev, I want to annote the pins, but not sure how to do in Easy EDA, named the pins in schematic but that does not show in board?
- as power source I want to use/salvage some of these cheap 18650 2600mAh USB "Power Bank"s gives me 5V a protection, charger and a cell. It ca even power other toys
- forgot a button and maybe a switch

So you see it is still a bit in a flow.

Please have a look and tell me if you see big errors or other quirks.

Cheers,
Carsten
Carsten Wartmann: Autor - Dozent - 3D - Grafik - Maker
http://blenderbuch.de/
 

Offline calli

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Oh:

- I choose a SOIC package as I think it is nice to solder at home, however I have no clue how the avaibility for such parts is today?
- EasyEDA: Every time I use the "Hand" tool the part in the schematic to select the part hangs on the mouse. Is this a preference or do I miss another select tool?!7
- I did not found WS2812b for soldering? Do I need to salvage them from stripes?!

Carsten
Carsten Wartmann: Autor - Dozent - 3D - Grafik - Maker
http://blenderbuch.de/
 

Offline calli

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Better share Link:

https://easyeda.com/carsten.wartmann/KrytaLED-c606fd6f46d342eaa2b26589556419c8

So did I something wrong? I had the impression that this topic could bring up some discussion?

Carsten
Carsten Wartmann: Autor - Dozent - 3D - Grafik - Maker
http://blenderbuch.de/
 

Offline cowana

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For a first board design, that looks pretty good!

A few points:
  • Decoupling capacitors. For removing noise from the power rails, you need decoupling capacitors. Recommended is 100nF by each of the microcontroller and LED.
  • Series resistor between microcontroller and LED. Highly recommended to prevent blowing up the LED, which is very sensitive.
  • Availability of base WS2812b LEDs: very common on either ebay or Aliexpresss. Try adding '10pcs' to your search.
  • Mounting holes: It's always worth thinking about mounting before you order PCBs - adding mounting holes for screws can make your life significantly easier than trying to clamp/glue them into place!
  • Pin naming: you'll have to add text manually to the silkscreen layer of the PCB if you want the PCB labelled.
  • USB connector: if you're looking to power the thing from a powerbank, it would make sense to put a (micro?) USB connector on the board, so you can use a common lead. That would also let you easily power it from a normal phone charger if required.
 

Offline calli

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For a first board design, that looks pretty good!

A few points:
...

Thanks! (it is of course not a very complicated design ;-)

I just showed it someone  on twitter and he came up with similar comments.

- Decoupling caps CHECK
- series resistors. Cant hurt. I experimented quite a much so far with the ws-leds without trashing one.
- mounting holes. Idea to consider, but due to mechanical reasons I cant't use screws very easy. I will look into my cas construction. (the LED needs to be quite flush with the top I think for best effect. I will experiment a bit)
- PIN Naming. I feared this. A bit sad...
- USB: no the salvaged USB Power Bank/boost/charger will provide these ports...

Big one: I swapped VDD and VSS on the WS LED... Doh!

Back to drawing board.

Thanks a bunch!
Carsten
« Last Edit: December 09, 2017, 04:48:39 AM by calli »
Carsten Wartmann: Autor - Dozent - 3D - Grafik - Maker
http://blenderbuch.de/
 

Offline cowana

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Big one: I swapped VDD and VSS on the WS LED... Doh!

I'm not sure if the original link is still the latest circuit, but what I'm seeing at the moment seems to be reversed for the WS2802 LED.

On the schematic, VDD should go to 5v, and VSS to GND (which is the opposite of the current wiring).

When you look at the PCB, remember that components on the bottom layer are mirrored - it's as if you are looking *through* the board.
 

Offline calli

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VDD/VSS... Well than my first reviewer made a mistake :-) I should have checked myself... I trusted him blindly because of his experience.

Thanks for the hint!

Carsten
Carsten Wartmann: Autor - Dozent - 3D - Grafik - Maker
http://blenderbuch.de/
 

Offline calli

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VDD/VSS I had it right in the first try, then due to a misunderstanding I swapped it...

Worked a bit in the project. Now to Check all.

Carsten
Carsten Wartmann: Autor - Dozent - 3D - Grafik - Maker
http://blenderbuch.de/
 


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