0

I have an Arduino Uno and I would like to attach a Waveshare 1.54“ display (red, black & white) to it.

All the specs tell me that it consumes 3.3 V which I have readily available on the Arduino Uno.

I could not get the display to work until I attached the Power pin to 5V instead of 3.3V.

I did try this with two different ePaper displays and the situation was the same.

I also tried to power the display with a Raspberry Pi‘s 3.3V (with the GNDs connected). But this did not work either.

So I am wondering what I am missing here, is it simply a power issue and my Arduino can‘t deliver the necessary current?

1

The answer lies in the FAQ for that display:

Why the e-Paper cant work with Arduino?

Answer:

The I/O level of Arduino is 5V, and the e-Paper should be driven with 3V3. If your Arduino cant drive the e-Paper successfully, please try to convert the level to 3.3V

You can also try to connect the Vcc pin to the 5V of Arduino to see whether the e-Paper works, but we recommend you not to use 5V for a long time.

So while you can run it from 5V, you really shouldn't, since you run the risk of breaking it.

Instead, you should employ proper logic level shifting to reduce the Arduino's outgoing signals to 3.3V and, more importantly, boost the incoming signals from the display to 5V.

  • Thanks for your Reply. I was only thinking VCC but not the output levels of the Arduino. So I need a logic level shifter or a voltage divider for each output of the Arduino – Besi Sep 17 '18 at 9:12
  • Yep. The Arduino expects minimum 3.3V on an input to recognise a HIGH. If you're running the display at 3.3V chances are the signals coming from the display will be slightly under that, and will want to be boosted slightly for the Arduino to recognise them. Running at 5V the signals will be proportionally higher and will register, but you can damage the display. For signals from the Arduino to the display they will be above the upper limit allowed, and could risk damaging the display, so they need reducing to around 3.3V. – Majenko Sep 17 '18 at 9:27
1

Update to those who have bought the display module recently (doesn't apply to bare displays). There has been a change and the new modules support 5V. From the display's user manual:

  1. For raw panel, its working voltage is 3.3V, note that when you designed you own driver board, level convert circuit is required if the working voltage of your board is 5V. Module/HAT version can support 5V voltage if the Module you buy is the new version which has been integrated convert circuit.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.