Power symbol on Picade screen


#1

Hi everyone. I’ve been playing with my Picade for a few weeks with no problem but this afternoon some times when loading games or when games access to the ad card am getting a lighting symbol in the top right corner of screen. I have a official pi power supply so don’t think it’s that. I’ve see other people have increased the power of the usb ports to 1200mA but am not sure how to do that. Thanks again everyone for your help


#2

The lightning bolt flashing is a low voltage warning. It means the voltage at the input to the Pi is dropping below 4.65 volts. Excessive current draw is usually the culprit. One of two things happen. The power supply voltage automatically drops to limit the current draw, or you get a voltage drop across the power cord as a result of high current. The wires have a small resistance. The thinner the wires the higher the resistance and the larger the voltage drop.
What model Pi are you using? I had that issue with a Pi 3B+, but it was a false indication. Doing a sudo apt-get update and sudo apt-get upgrade fixed it.
What else are you powering from your power supply on top of the Pi and picade hat?
The increasing the available current to the USB ports is done with a config.txt edit.
You add max_usb_current=1. As far as I know that’s not required anymore, its 1200ma by default now. It only applies to certain Pi models anyway. The 2B or maybe the B+ I think? It wouldn’t help in this instance anyway.


#3

Some sites like Adafruit, sell 5.1 or 5.2 V supplies to mitigate this issue. You still get ~5V at the input to the Pi instead of 4.9 or 4.8 etc under heavy load. Just a FYI info post. I don’t like linking to the competition but Adafruit and Pimoroni each sell each other products.
https://www.adafruit.com/product/1995
IMHO 2.5A is iffy if you have a lot of extra hardware attached to a Pi and powered from the Pi’s power supply,like a display for example. especially if that Pi is a 3B or 3B+. I’ve modified several of my Pi setups to accept a barrel connector for power and gone to 4A and even 10A 5v supplies. No flashing lightning bolt.


#4

It looks like the Pi foundation does it too, the official power supply is 5.1V. Maybe they should go to 5.2V and 3A?
https://shop.pimoroni.com/products/raspberry-pi-universal-power-supply


#5

I believe the max_usb_current=1 entry in /boot/config.txt hasn’t had any effect since the Pi 3, which supplies 1.2A by default. If you have an earlier Pi, though, you might see some benefit by adding this line to the config.

Other likely culprits for voltage drop can be flaky cables, or not-quite-seated connections.

If your Pi isn’t browning out or crashing due to the lightning symbol, then I believe you can safely ignore it. There’s a little leeway between it warning you, and it actually causing an issue.


#6

Along the same lines as these questions … I wonder is there any limit to the INPUT current circuitry of the Pi-3’s.

I have got hold of some barrel to micro-USB adapters which would allow the use of a more powerful 5v source direct to the normal Pi-3 power input socket. Or is there some protection circuitry that would limit current throughput?

No project in mind - just a “what if” question.

My only knowledge of this relates to Arduino which typically has a 1/2 Amp polyfuse on its input to prevent damaging a PC USB port when used for sourcing power. Anything similar on the Pi?


#7

The 3B+ and other models have a poly fuse to limit current draw. The only exception is the Pi Zero, no poly fuse on a Zero. Be aware though, If you supply power to the Pi via the GPIO pins you bypass the poly fuse.
I have several Pi projects that use a barrel connector for power. I have 3A, 4A and 10A 5V power supplies I use with my Pi projects.
I’ve feed power to the Pi via the GPIO pins in a few of my projects, it was just easier to do it that way. I’m aware of the consequences of doing it and take precautions when I can. I’ve added my own poly fuses in some of my projects.


#8

One way around the USB devices 1.2A Max Current limit is to make your own USB cables. I did this on my bread board Pi. On the male plug that plugs into the Pi, only the Data + Data - and ground pins are wired. On the other end with the female connector those same Data + Data - and ground are wired, and the +5V is sourced right from my power supply. I put a 500ma poly fuse in each cable as protection against a short. I was extending the USB ports to the front of my project anyway. My Pi is mounted behind a Pi foundation 7 inch touch screen and hard to get at. I wanted two easy to access USB ports front and center.


#9

Check the Maximum total USB peripheral current draw column to see what value the poly fuse is. It will also tell you which model have the 600ma 1.2A option. 3B+ hasn’t been added yet?


#10

Hi . I am using a pi3 B with everything running off the usb (screen and pcb)


#11

IMHO you want the official 2.5A power supply. Which from your first post you already have. 3B allows 1.2A to USB by default so nothing to be gained my that config.txt edit. I do believe the Picade hat has its own USB power port, which one are you using, the one on the Pi or the one on the Picade Hat? I’d try using the one on the Picade Hat. @gadgetoid would likely know the ins and out of doing that.
IMHO even 2.5A is iffy these days, especially when driving a display and Pi from the same power supply. Just my 2 cents though.