Pro supermini nrf52840 not putting out 3.3V on EXT_VCC - Page 1
Forum section: electronics / general

author: jimmyc_
author_rank: Contributor
timestamp: April 08, 2025, 03:42:33 am
content: Hello chaps!I'm using a Pro supermini nrf52840https://wiki.icbbuy.com/doku.php?id=developmentboard:nrf52840which is a nicenano! v2 clone for the first time and using it to power an ICM-20948 IMU.I was powering the supermini nrf52840 using USBC cable (5V) but i am not getting any 3.3V out from the EXT_VCC pin. I've confirmed this using my multimeter which showed 0V at EXT_VCC and GND.Any ideas if EXT_VCC needs to be activated from code?Thanks in advance!

author: WattsThat
author_rank: Frequent Contributor
timestamp: April 08, 2025, 04:54:12 am
content: From the link you provided:External VCC controlhint When P0.13 is set to low, the power supply to the 3.3V, VCC pin will be turned off. This is useful for reducing components that use power when idle (e.g. RGB, LEDs).

author: jimmyc_
author_rank: Contributor
timestamp: April 11, 2025, 09:53:20 am
content: I've set P0.13 to high and i still get 0V from VCC pin. I'm not going to jimmy (hehe!) around any longer and getting 2 x nrf52840 dongles from digikey. Should i get the nrf52840 DK instead of the dongles? There's a jlink on the DK, I'm not sure how important is it to me yet. My intention is to prototype a wearable device which the nrf52840 dongle is of the correct size.Also, is there a breakout board for the nrf52840 dongle with its castellated edges?ElectroGods, Please tell me!

author: __george__
author_rank: Contributor
timestamp: April 19, 2025, 02:34:06 pm
content: I am wondering if you have a faulty unit. Checking the schematic of your board it seems that indeed setting the P0.13 should enable the 3.3V power.It seems that they use the voltage regulator ME6217 to enable or disable the 3.3V. The datasheet of this is available here:https://datasheet4u.com/pdf-down/M/E/6/ME6217-Microne.pdfYou only have two components which look like this and the pinout is available in the datasheet. It might worth spending 5 minutes with your multimeter and check what is happening with the voltage regulator.As for the nrf52840 dongle and the DK. In my opinion if you want to develop anything you need to have a debugger available. If you have a standalone debugger and a soldering iron to connect the debugger pins (and the GPIOs) on the dongle and at the same time you are fairly certain that 15 GPIO are good enough for you then go for it. In any other case at least one DK is for sure a better option.I am not aware of any breakout board but since the pins on the dongle are fairly standard (2.54 mm pitch):https://docs.nordicsemi.com/bundle/ug_nrf52840_dongle/page/UG/nrf52840_Dongle/hw_external_connections.html#fntarg_1You can easily find a stripboard on aliexpress/ebay and solder the pins to make your own expansion board.

author: __george__
author_rank: Contributor
timestamp: May 17, 2025, 05:45:11 pm
content: I got to play with this board today and I tested what the original author was asking about. So I can now confirm that setting the P0.13 does indeed enable the VCC as expected. So probably the problem of the original author was a faulty board.