Author Topic: SSD1309 OLED display custom i2c board  (Read 224 times)

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Offline LordyVader

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SSD1309 OLED display custom i2c board
« on: April 20, 2021, 10:32:31 am »
Hello,

I have a SSD1309 OLED display with 24 ZIF connector only. So I went to a website of manufacturer and started with design of a board so I can make an i2c connection with STM32 MCU. This is the datasheet of the display, and here is an example how to make an interfacing.

So based on this I made this scheme:


Other OLED display I saw on the internet that have already designed and ready to use board with i2c procotol are powered with standard 3.3 VCC power pin like on this picture. But here, it is noted in datasheet VCC = 7.0V ~ 16.0V for Panel driving and VDD  = 1.65V ~ 3.3V for IC logic. So I decided to ignore that and give it a try with 3.3V as I don't want to use some additional power for the device other then the same power I use for STM32 MCU. Unfortunately, display is not working and I want to be sure is maybe this the reason?  Here is also the link of library I used: https://github.com/afiskon/stm32-ssd1306

Can someone tell me how to make it work? Thank you in advance
« Last Edit: April 20, 2021, 10:36:12 am by LordyVader »
 

Offline ebastler

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Re: SSD1309 OLED display custom i2c board
« Reply #1 on: April 20, 2021, 10:52:04 am »
The datasheet as well as all your connection examples show that a higher Vcc is required. You have not connected anything at all to pin 23 (the capacitors to 3.3V don't do anything for DC...), so I would expect that to be the reason for the malfunction.

Have you tried to supply a voltage to pin 23 for testing? You can use a 9V battery if you don't have a second power supply around.

EDIT: The SSD1309 does indeed require the external higher-voltage supply; unlike other driver ICs for small OLEDs it does not have a built-in charge pump (DC-DC converter). So the PCB you saw, which enabled single-supply operation at 3.3V, must have provided that DC-DC converter.

Here is a project and schematic to build your own DC-DC converter, if you do not want to discard the display and buy one that is easier to connect: https://hackaday.io/project/173753-oled-breakout-board-with-dc-dc-step-up/details. Note that the pin numbers on the ribbon connector seem to be different from yours!
« Last Edit: April 20, 2021, 11:03:28 am by ebastler »
 

Offline LordyVader

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Re: SSD1309 OLED display custom i2c board
« Reply #2 on: April 20, 2021, 11:53:04 am »
So SSD1309 needs that 7-16V no matter what, too bad to hear that. I will try with 9V battery just to make some testing and see how it works.

This link you sent, there is this "Compared to the more popular SSD1306 which has a built-in charge pump". So I had a look for this 1.3" SSD1306 OLED display, it also says here 6-15V for VCC, but on Interfacing manual for i2c protocol says VCC Generated by Internal DC/DC circuit. I guess that means I don't have to worry about it with SSD1306 then?
 

Offline ebastler

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Re: SSD1309 OLED display custom i2c board
« Reply #3 on: April 20, 2021, 03:47:54 pm »
Right, the SSD1306 seems to have the DC-DC converter built into the driver IC, so you only have to provide a single supply voltage. It is a bit of a trap that the SSD1309 does not include the converter!

In your shoes, I would do the experiment with an external 9V or 12V supply for your SSD1309 display, as a learning experience -- but then switch to an SSD1306-based display for the final system you want to build. (If you can find one in a suitable form factor.) Adding your own DC-DC converter externally is probably more hassle than you need...
 
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