SSD1306 VCC, SCL & SDA voltages

Hi,

In https://cdn-shop.adafruit.com/datasheets/SSD1306.pdf I see the following:

• Power supply
o VDD = 1.65V to 3.3V for IC logic
o VCC = 7V to 15V for Panel driving

I'm using my SSD1306 with an ItsyBitsy M0 (SAMD51) which operates at 3v3 but provides both a 3v3 and a 5v output. I've connected the pullups for the I2C communication (SDA & SCL on the SSD1306) to 5v via 4.7k ohms resistors. And I've connected VCC on the SSD1306 to the 5v pin also. Everything is working fine although I'm concerned about the longevity of the display.

With respect to how to do this correctly, i.e. within the specifications provided by the manufacturer in the datasheet, I'm thinking that the pullups should be connected to 3v3 output instead of the 5v output. And I'm scratching my head with respect to what I should be using for the SSD1306 VCC; is that 'panel driving'? 7v - 15v? Any thoughts are appreciated.

Dan

It is always wise to post a link to the actual display that you have bought.
Or at least post a photo of the pcb.

Most (but not all) SSD1306 display pcbs have an AMS1117-3.3 voltage regulator (or equivalent).
If there is a regulator chip you connect VCC pin to 5V.
If there is no chip, you connect VCC to 3.3V

Most (but not all) SSD1306 boards have I2C pullups mounted.
Pullups should be pulled to 3.3V not 5V
This is very important with SAMD21, SAMD51, SAM3X, ... which are not 5V tolerant.

If you provide the link, you would get accurate answers.
Otherwise, we can only write generalisations. And some readers might not understand a technical reply.

David.

LInk: 0.91 0.96 1.3 1.54 2.42 inch IIC Serial White blue OLED Display Module 128X64 I2C 12864 LCD for Arduino|LCD Modules| - AliExpress
Pic attached.

SSD1306.jpg

SSD1306.jpg

Qn generally means transistor.
Un generally means integrated circuit.

Your Q1 looks like a voltage regulator integrated circuit. You can read the printed part number and Google it.

I guess that R2, R3, R4 are all printed 472 i.e. 4k7

If my guesses are correct:

  1. connect VCC pin to 5V
  2. you do not need any external pullups.

David.

Excellent, thank you sir. The only question that remains, then, is what is meant by the datasheet when it indicates:

o VCC = 7V to 15V for Panel driving

Dan

It just means that the Panel requires a specific voltage.

You have bought a ready made pcb that contains any external electronics required by controller and panel.
You just need the 4 pins on the header. And connect to the MCU with the correct logic voltages.

Think about a petrol engine with Spark plugs. You connect a 12V battery. You don’t connect an external 15kV power supply because the engine has the necessary external components to generate the 15kV spark.

David.