ESP8266 Community Forum

- Sun Jul 02, 2017 10:55 am #67826 This is a warning folks!

I'm very fond of the little SSD1306 (I2C) OLED displays and have used them in lots of projects. Recently I built a new project. I plugged in my only spare OLED & it didn't work. I knew it SHOULD work!
I buy these things on ebay, usually from the cheapest seller. When I looked closely, the pinout on this display was different to all of the others I'd used. Crucially the Vcc & GND pins are reversed!
This isn't a big deal if you're using jumper wires but I am using a PCB which expects a particular pinout
Take care...

Ian

- Sun Jul 02, 2017 5:59 pm #67836 Maybe put a couple of pics of the "Good" and "Less good" displays, so we know what to look for.

These are the OLEDs I have at the moment (they're all GND - VCC - SCL - SDA):


Anyway thanks for the warning.

Assumption is the mother of all f*ckups. At least: that's what I'm assuming.

- Mon Jul 03, 2017 10:45 am #67879 Interesting! I only use the 0.96" displays which I'd always imagined were identical. Clearly they are not. I have several of these displays which have a pinout: Vcc-GND-SCL-SDA and only one which is pinned GND-Vcc-SCL-SDA like yours is.
As I indicated, it doesn't really matter if you're using a breadboard. It matters a lot if you're using a PCB, as I am.
Another reason why I prefer this configuration is that many other devices seem to follow the same pinout. Particularly the Bosch (4 pin) sensors: BMP180, BME280 etc.
I generally design PCBs for my students to use & it's very handy to have I2C devices with the same pinout.

This is the board I'm currently working with:

Top left is a group of I2C sockets which are all wired Vcc-GND-SCL-SDA

Ian