Waveshare LCD1602RGB - no display at 3.3v

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Hi, I can get this unit to display text with 5v VCC on an Arduino UNO using the demo sketch from Waveshare. At 3.3v VCC, the backlights are lit but the display is dark and there is no text.

Could someone please tell me if this is normal behaviour. The datasheet seems to suggest otherwise.
If I have missed somthing or there is a fix, please let me now.

1 Like
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Hi Glenn,

Welcome to the forum!!

I’d stick to keeping the display on the 5 V Vcc pin (usually there is a relation between the Vdd and logic levels, where if the logic inputs are higher than Vcc it can damage the board)

If you have a strict 3.3 V device like the Raspberry Pi Pico or using a logic level converter it might be a test to confirm the behavior.
But it does sound like it might be a hole in the manufacturer’s documentation.

Would running the display at 5 V cause an issue with your project?

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Hi, Liam, thanks for the response.

I bought the display to use with a Raspberry Pi Pico so as to avoid using a logic level converter and all that goes with it.

Sadly, this unit will not achieve that. The real capability of this unit is only evident if you delve into the documentation for AiP31068L ( LCD ) which is referred to on page 6 of the Waveshare datasheet.

Core may wish to review its page for the CE07881 because it clearly says that the unit works with 3.3 and 5v. And if my unit is typical, this model will only work with 5v.

Thanks again for responding.

Regards

Glenn.

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Hi Glenn,

Do you have the code that you were using there? I think I might have one kicking around in my box of parts and can do a quick test on my end?

(Were you connecting the same as on the Core/Waveshare website?)

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Hi, Liam

I have attached a copy of a file containing the code for a several platforms that I downloaded from the Waveshare website - this is the link .

I tried set up the unit for the the RPi and RPi Pico as shown in the pictures on the your (and Waveshare’s) web sites. I used the python program on the Pi and the c program on the Pico.

I tried the Pico on I2C1 as well as I2C0 as well as other I2C pin sets as well (after making the necessary changes to the code). No luck.

I resorted to the Arduino after these tries. I wired it up as shown on your site but it did not work at either 3.3v or 5v. I connected SDA and SCL to A4 and A5 and it worked on the 5v supply but not on 3.3v. At 3.3v, the backlights light up but there is nothing on the display.

Regards

Glenn

LCD1602-RGB-Module-demo.zip (245 KB)