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Hi,

I'm building a MCU type controller and I'm starting to design some PCB's for the various modules.

I'm planning to share them here so other users can use them if they want, if that's ok.

 

The first and simplest one is an 8xOLED carrier board to connect to J15A of the STM32F4 core.

Initial tests on a breadboard with 2 screens work fine.

It is my first time using Kicad and also designing a 2-layer board, so I'd like to get some feedback before sending them to the fab house.

  • OLED's are 0.96'' SSD1306 4-wire SPI type
  • Mechanically the OLED's are plugged into 1x7 sockets
  • Each 'channel' is exactly 1.1 inch wide. It leaves a little wiggle room between the screens,
    and should allow the case too be quite compact 
  • I remember seeing another schematic with added 100nF decoupling caps, but they're not on Thorsten wiring diagram,
    so I'm wondering if I should add those

 

NOTE: I'm going to extend the board to avoid having the holes running under the OLED's.

oled_back.jpg

oled_front.jpg

oled_pcb_top.png

oled_pcb_bottom.png

oled_schematic.png

ssd1306_test.jpg

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Posted (edited)
15 hours ago, Phatline said:

i think you will need a the cap and resistor on reset for every display (they told me...dont know if necessery)

Thanks, but are you sure ? I distinctly remember reading @TK. saying only one is needed, at least for 8.

It looks like a simple RC cell, and I don't think the current drain on the Reset pin would alter the time constant.

Edited by Lorcan
Mention Thorsten
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On another note, I looked at current consumptions of various OLED's,

and according to this page, a 128x64 0.96” can pull 21mA at max contrast with all pixels lit.

As the STM32F4 board docs state, the integrated 3.3V regulator can only supply 100mA max.

I wonder if problems some people were having with multiple OLED's might be related to that.

So to be on the safe side and to avoid heating the poor little SMD IC,

I'm going to add an optional on-board 3.3V regulator or input.

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if height is a problem this could spare 2mm: https://www.mouser.at/ProductDetail/Hirose-Connector/MDF7-7S-254DSA55?qs=%2Fha2pyFaduiZ71eBiARkwzzUReMZP2WhzZTuqPhRayn1qNB0%2FX2TxKoytKf%2BS9gq

(not realy needett when shorten  the pinheaders of the displays by hand, and removing the header-plastic)

but maybe its whise to use standart pinheader - because of price and aviable...

..just a thought.

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Updated the PCB, hopefully it's close to being ready for fabrication.

  • Added decoupling capacitors (optional, just in case)
  • Added external 3.3V option w/jumper selection
  • Cleaned up traces etc

I'll put all the files on github when I've confirmed everyhting works as intended.

 

oled_back.thumb.jpg.71a82d8bb073bce46e530d401a0ed677.jpgoled_front.thumb.jpg.eb99759c133dc682ba2df2d2fc218d7e.jpg

oled_schematic.png

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Posted (edited)
On 3/30/2021 at 12:42 PM, novski said:

Nice Work. I did same once. See: http://wiki.midibox.org/doku.php?id=fadercore_-_vlr-8odisp

i think i have some pcb still laying around. 

Thanks ! Yes I've seen your work too, very impressive !

I want to make my own boards so I started with the simplest PCB to learn KiCad. It's quite a wonderful piece of software,it has evolved a lot since I last tried it. And it's looking even better in the upcoming version 6.


I've sent the PCB for fabrication yesterday, let's hope I didn't make any stupid mistakes !

Edited by Lorcan
typo
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