Hello! I am relatively new to this stuff (and this is my first post here). I am trying to set up the pimoroni pico lipo shim with a rp2040 (not a w, just a standard pico).
I soldered it to my pico and when I plug my battery in I see the white light turn on (and it seems to have power, my led flashes as expected). However, pressing the button just resets the unit. It does not seem to be able to “power off” at all, it’s just turning on when I plug in any power source.
I checked that my contacts are soldered cleanly (I’m relatively new to soldering, so they’re not great but I don’t think I bridged any contacts or had bad connections anywhere).
Any ideas as to what could be going on? I can provide photos as necessary. Just wondering if this is a relatively common issue.
Hi! Yes, this is strange and definitely not what you expect. The power-button should turn power on/off. I am not sure if the system starts in power-on state when plugging in a battery, but otherwise the button should work as a toggle.
It might indeed be helpful if you post some images of your soldering.
I have a Pico Lipo Shim soldered to a Pico (non W, V1). With a heathy battery attached, mine retains the last state it was in, on or off. If I toggle it off, it stays off when the USB cable is plugged in.
Off, with battery attached, no USB cable plugged in,
no LED’s are on.
Off, with battery attached, USB cable plugged in,
Red LED is on.
If I then turn it on the White LED turns on.
Unplug the USB Cable and the RED LED goes out, White stays lit.
Toggle it off and all LED’s are off.
Here a photo of my soldering (I am new to this, so I know some of the soldering work is pretty bad). It’s hard to get photos of the joints, but from what I can see I don’t think I bridged any connections.
It makes sense that it would retain the last state, so that answers that part. But the button does not seem to be toggling power for me. If I press and hold the button, the LEDs go off. But when I let go of the button, it is on. Pressing it just seems to restart it, not toggle power.
I don’t have a lot of electrical experience, so I’m uncertain the implications of that behavior I’m experiencing and what it could potentially mean. :(
Thanks for the help so far! Let me know if you need additional details/photos!
Your soldering doesn’t look too bad, from what I can see in the photo’s. What state is the battery in? Might want to just let it charge for a while and then try turning on off again.
What does it do with USB plugged in, but no battery?
The default with no battery or a dead battery should be off. That’s what mine does with no battery connected. It also won’t retain the last state. Unplug the USB and plug it back in and it goes back to off.
No battery, plugged in to USB:
White light immediately, sometimes red light flickers. Pressing button turns off white light when held, but upon release white light is back on. Seems to be doing a “reset” as the LED on my board flashes when the board gets power normally and that happens when the button is pressed.
Battery attached, no USB:
Same behavior as noted above. White light on immediately, pushing button just resets the board. Does not toggle power.
Both battery and USB attached:
Strangest behavior yet. White light on immediately, but the button seems to be working sometimes? Sometimes when I push it, power is toggled. Sometimes, it just resets. I’ll attach a video link, maybe that will help. https://youtu.be/03YWnh5Cvqc?si=DYpWledhEld4ldIU
Uncertain of what could be wrong here. Button seems inconsistent. I have a second shim (ordered 2), is it possible this one is just defective? I could try soldering a new one, but wanted to start with troubleshooting before replacement.
That is my thought too. I’ll try the other shim on this same pico and see what my results are. If that one works, I’ll assume this shim is defective. If that one doesn’t work, could be my pico.
Before desoldering: this is a toggle button. Never keep it pressed. Pimoroni has added some debouncing components (RC) so that it does not randomly pick up multiple presses. But keeping it pressed is definitely a bad idea.
Desoldering will probably be a lot of work without good equipment and chances are that you waste your time without meaningful results. The price of the Pico is not worth it.
This may sound like nit picking, that’s not my intension. The button circuit is a toggle function. The button itself is a normally open momentary contact push button. It’s a short circuit when pressed, and open circuit when released.
I did some more testing on mine. If I press and hold the button down, it toggles the on off state just the once. If it’s off it turns on etc. Which sounds to me like the way it’s intended to work.
So on yours, something has gone afoul. If you have a male dupont jumper handy you could use it to short the switch contacts, bypassing the button and see what happens. It would be the two contacts at the back of the button, right at its base where it meets the circuit board.
