BAT(-) = GND ? (using GND as battery -)

[sangh]

i am trying to deign keyboard, mounting XIAO NRF52840.

but problem is SMD pads to connect battery.

i want to use PCBA service of jlcpcb, so i think pogo pin can be used to access those pads.

but problem is battery pads are too close to place pogo pin.

so i want to use only one pogo pin to connect battery(+), and use GND pin as battery(-)

i want to know if BAT(-) pad and GND (GND PIN), GND pad (next to reset pad) are same, or different somehow inside XIAO.

[PJ_Glasso]

Hi there,

And Welcome here,

So this has been discussed much here, check out some of the other threads on PCB mounting the Xiao.
NO, DO NOT use the BAT GND. like that. The onboard battery charger doesn’t like that type of configuration.

Just solder the BAT PADs, it works good.
Use the holes in the PCB like others have with much success.

Xiao nrf52840 Surface mount

Hello, I’m wondering if anyone has any experience with surface mounting the XIAO nrf52840 to a PCB. I’m trying to use it for a wearable and so avoiding the thickness/height of headers would be good. I’d also like to use the VBATT pads on the underside connected to the battery which will be VDD. Doing it this way because the NRF52840 can’t output enough current for what I have on the rest of the PCB so I was going to use the battery as Vdd and Gnd and connect these to the Vbatt pins so I can de…

HTH
GL PJ

[sangh]

Thanks! It looks like this design makes soldering pads easier than designs i saw before.

But I’m actually trying to avoid doing any soldering at home, so I’m looking for ways to set things up without soldering.

I’ll use non-rechargeable CR2032 battery, like example below. and i will remove it when I need to connect the board to a PC for flashing. So I don’t need to worry about charging.

Here’s one of the reference projects I found:

https://github.com/hazels-garage/bad-wings/tree/master/slim

In this project, the three pins on the XIAO BLE ( B-, GND, and GND pad ) are all connected together by the PCB.

My question is: are those pins internally connected on the XIAO BLE board without any electrical logic?

1. If they’re already connected inside the board, then I don’t see a reason to connect them again on the PCB.

2. But if they’re not connected internally, is it safe to connect them externally like that?

I’ve been trying to read through the XIAO BLE documentation and posts like this to find out, but I don’t really have much background in electronics, so I’m having a hard time understanding them.

[PJ_Glasso]

Hi there,

Ok , well Your doing pretty good so far Stay at it , You will get there. It’s not rocket science but takes some attention to the details and it always works!.
Yes , I have seen this one before. With the Exceptions you stated , then you would be ok. Just no non-rechargeable plugged in at the same time as the USB-C. so Ok there.

I have them connected because I’m driving a Solenoid using an FET and need everything the BATTERY can give , normally they are not, and AFAIR (i’m older) they are NOT connected internally but you can check with a OHM meter. The external GND pin (13) and the (-) batt Pad.

Lots of good info here, so read it all and ask any questions you have as there are some VERY knowledgeable folks dropping in here.

HTH
GL PJ

here’s the Source,

Is BAT- the same as GND? (XIAO Seed BLE Sense)

I am planning a battery-operated project using the XIAO Seeed BLE Sense as the MCU and 19 NeoPixels. Here is a picture of my proposed wiring. My question is if the Negative Battery ‘pin’ is the same as the ground (GND) pin? Or are they different somehow? And what about when you plug in the USB to recharge the battery? Is the USB ground the same as the Battery (-) the same as the GND? And in my schematic, do I need to run a wire from the GND pin to the LEDs GND as well as the Battery (-)? Or do…

after a few posts , you will get enough forum cred to post your own threads and pic’s , etc.