Hi, I have a nodemcu v3 esp8266. The 2x16 LCD display is powered by VCC = 5 V, while the 0.96'' OLED is powered by 3.3 V. I have an I2C converter attached to the LCD display, the OLED also uses I2C. Knowing that the LCD is connected under 5 V and the OLED under 3.3 V - can I connect both...

There will probably be no communication with the 5V LCD, because in the datasheet note in the first better LCD the logical one starts at 3.5V. You need to use a converter or circuit that will match the logic levels.

. As long as there will be 3V3 logic states on the I2C lines on the NodeMCU side and there is already a 5V/3V3 logic level converter on the LCD side, then you can.

I managed to run the LCD without a converter - the only problem was getting the bias correct - but I got around that a bit by running the LCD in single line mode (different refresh rate) and everything is readable.

Connecting 5V LCD and 3.3V OLED to Same I2C Pins on NodeMCU ESP8266

Travisek 1239 3

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#1 19193037 18 Jan 2021 17:31

Travisek Travisek

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19193037 18 Jan 2021 17:31

Hi, I have a nodemcu v3 esp8266.

The 2x16 LCD display is powered by VCC = 5 V, while the 0.96'' OLED is powered by 3.3 V.

I have an I2C converter attached to the LCD display, the OLED also uses I2C.

Knowing that the LCD is connected under 5 V and the OLED under 3.3 V - can I connect both displays under the same SCL and SDA pins to the ESP (D1 and D2) ?

Thanks
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#2 19193136 18 Jan 2021 18:07

lucass17 lucass17

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Post #2
19193136 18 Jan 2021 18:07

There will probably be no communication with the 5V LCD, because in the datasheet note in the first better LCD the logical one starts at 3.5V. You need to use a converter or circuit that will match the logic levels.
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#3 19193353 18 Jan 2021 19:21

Anonymous Anonymous

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Post #3
19193353 18 Jan 2021 19:21

Travisek wrote:
For the LCD display I have an I2C converter attached , the OLED also uses I2C.
Knowing that the LCD is connected under 5 V and the OLED under 3.3 V - can I connect both displays under the same SCL and SDA pins to the ESP (D1 and D2)?
.
As long as there will be 3V3 logic states on the I2C lines on the NodeMCU side and there is already a 5V/3V3 logic level converter on the LCD side, then you can.
#4 19253495 13 Feb 2021 15:22

ArtGateOne ArtGateOne

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Post #4
19253495 13 Feb 2021 15:22

I managed to run the LCD without a converter - the only problem was getting the bias correct - but I got around that a bit by running the LCD in single line mode (different refresh rate) and everything is readable.

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Connecting 5V LCD and 3.3V OLED to Same I2C Pins on NodeMCU ESP8266

Connecting 5V LCD and 3.3V OLED to Same I2C Pins on NodeMCU ESP8266

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