5v DC power supply options?

[Dougmeister]

Using a Pico that is 3.3v powering:
* a mono amp
* 8 controllers (each w/ LED button, mini vibrating motor, and a resistor)
* Generic button

I was using the USB pin to push 5v to my 16x2 LCD display, but that only works when I am connected to my computer. I can't find a wall wart or DC adapter that will work directly from an AC outlet.

A) Which Adafruit DC adapters can I purchase that will work?
B) Or which "wall warts" can I buy from Adafruit that will work?
C) Or will purchasing an I2C Backpack solve my problems? (To 'convert' the 3.3v of the Pico to 5v for the LCD)

Thanks.

[mikeysklar]

Can you use a 5v/2A wall adapter with USB-A port? You could run a USB cable to the Pico W and continue using the VSYS port for the 16x2 LCD.

https://www.adafruit.com/product/1994

[Dougmeister]

To get 5v from the Pico, do I use pin 40 (VBUS) or pin 39 (VSYS)?

[mikeysklar]

Good point / question. I looked this up in the Pico datasheet.

VBUS can output 85 - 95mA @ 5v and would be the preferred way to power an external peripheral like the 16x2 LCD.

Screenshot from 2023-03-21 16-49-14.png (25.4 KiB) Viewed 104 times

VSYS is really for more esoteric input purposes, but they do have a lot over lap and can be shorted in some circumstances.

[Dougmeister]

So I could buy an I2C Backpack -BUT- I *should* be able to power the LCD from the VBUS pin of the Pico, right?

(That is currently working when I have the USB cable connected to my laptop, but none of the wall warts I have seem to work).

Would any/all of these DC adapters work if I didn't want to buy the I2C backpack?

https://www.adafruit.com/product/4298
https://www.adafruit.com/product/1995
https://www.adafruit.com/product/1994

[mikeysklar]

VSYS should work fine without the 16x2 i2c breakout.

#4298 - Is USB-C so that would not work with the Pico W.

#1995 or #1994 - Are good choices for USB wall power.

[Dougmeister]

Thank you.

I am going to try one of those DC adapters.

Currently, I have seven (7) wires going from the Pico to the 16x2 LCD: RS, EN, D5-D8, and the LED (backlight?).
If I need to free up more pins and decide to go with the I2C backpack, where do the two wires go?

I guess one wire goes from any one of the "SCL" pins (e.g., GPIO1) to the I2C Clock pin, and the other from any of the "SDA" pins (e.g., GPI00) to the I2C "Data" pin...?

Then the other 5 wires (plus ground and 5v) go from the I2C Backpack to the 16x2 LCD Display?

[mikeysklar]

You guess correctly that you will be using GP0/GP1 i2c pins.

Code: Select all

import board
import busio

i2c = busio.I2C(scl=board.GP1, sda=board.GP0)

You will still need to supply power/gnd as well to the backpack, but the rest of the connections the backpack will handle to the 16x2 LCD.