Switching regulator with the feather RP2040 [SOLVED]

Projects General Guidance
1

I'm trying to create a datalogging device that can run on batteries. I've been using the arduino nano but I want a battery charger and more program storage as I've had to minimise a lot of code for the nano program. I was told about the feather RP2040 in my last post, but I've realised that the 2004 LCD I use requires a 4.8v minimum input voltage.

I'm thinking about using a switching regulator to output 5v to the LCD and any other components that require 5v. Is it that easy to connect the USB pin to a 5v switching regulator and have the regulator power the LCD?

Edit: I've solved it, the only way it works on 3.3v is if there is a potentiometer connected to V0; I only wasn't using a pot on V0 as I have none spare for my project.

2

you may be able to use VBUS to supply 5V but you will require a level shifter to convert the LCD 5V logic to RP2040 3.3V logic - do not connect 5V logic devices directly to the RP2040 you could damage the device

recommend you change to a LCD which works off 3.3V, e.g. interfacing-ssd1306-oled-display-with-raspberry-pi-pico

3

Yea it is easy but borderline. I am assuming you are using a backpack and not driving the display directly. Keep it on the lower side of 5V close to 4.8 and it should work. Use pull up resistors in about the 3K range to the 3.3V.

4

I'm sure the minimum input voltage for logic is below 5v- I have a 16x2 LCD running the same driver and it works fine on 3v3.

Could I not just implement resistors if I needed to rather than using a logic level shifter?

The LCD driving voltage is the only characteristic of the LCD that require around 5v.

5

I'm not using a backpack, I might purchase a few however.

6

That won't work.
However you can connect a 5V boost regulator to the VBAT (Bat) output pin to get your 5V

7

Can you tell us how you solved your problem.

8

I posted it in the first post at the bottom, marked as Edit:

However, my problem now is that my SD card adapter module does not work at 3.3v, even though it operates at 3.3v. I've tried shorting the 3v3 regulator and removing and shorting the level shifter, but it won't work, so I'll need to purchase a boost regulator for that 1 component.

9

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