Is there a way to power a nucleo 64 board from a 3V external battery without damaging the board?

[BCora.1]

Hello,

I'd like to power my nucleo L152RE from a 3V external battery.

I thought this should be easy but then I read that some soldering needed to be done? Is that true? I'd like to be able to power the board from an external 3V battery to use it as an autonomous device, then reconnect it to the PC via USB when updating my program, or just experimenting with new programs.

Is there a way to power the nucleo from an external 3V battery without soldering or unsoldering stuff?

Thanks for your help.

[TDK]

The user manual outlines all the different power options, including one for a 3.0-3.6V external supply, but it requires you to cut some traces.

https://www.st.com/resource/en/user_manual/dm00105823-stm32-nucleo64-boards-mb1136-stmicroelectronics.pdf

Note that battery voltage is not a constant.

[Tesla DeLorean]

Perhaps you could use a USB "juice box" type battery, and that would remove the need to interpret the schematic or solder anything.

[BCora.1]

It seems an alternative would be to cut the board in two (separate the programmer/debugger part from the MCU part). This would permit to power the MCU with a 3V battery. But would there be a way to wire the two parts together again to reprogram the microcontroller after that? I mean a way for a noob to rewire the two parts together and program the microcontroller again?

[BCora.1]

Thanks for the replies, guys.

You replied just while I was writing the preceding message.

A USB juice box wouldn't solve my problem.

The main issue I have is that if you use USB, or a 5V battery, to power the board, you have this super annoying power led that lights on.

I don't want that light to be turned on when I use the board.

This might sound silly but my first project with that board is to use it as a kind of alarm clock. So I want to use this device at night, and I have trouble sleeping with even the slightest amount of light in the room. Maybe I should have asked about just the LED but well, I didn't think it would be so complicated to power the device on 3V since it was written everywhere in the specs that it could be done. I didn't think I had to irreversibly damage the device to do so.

Maybe the led could be covered by something, a kind of glue or something, but this led is very powerful, and also very close to the other led I'd like to use to display the time in morse code when it's time to get up, so, it would be so much more satisfying to just use the MCU without that power LED running at all. Plus it would save energy since I plan to use it on a battery, it would be silly to have that power LED running all night on a 3V battery.

[BCora.1]

Maybe I should have rather searched for a way to program a chip that's available in SPDIP format, like this one:

https://fr.rs-online.com/web/p/microcontroleurs/7249924/ (it's a STM8S chip)

This way I could program it and then insert it on a breadboard with battery power, a few buttons and a LED.

Again, I'm a total noob and I think I got lost in the incredible variety of stmicro chips and programming boards.

I guess the kind of pretty high end chip that comes with my nucleo L152RE is not available in a format that you can clip on a breadboard. I wonder how people flash these chips without a development board, and how they can be used for limited series production. Maybe they're just not intended to be used for limited series?

[KnarfB]

The Nucleo-32 boards fit on a breadboard nicely.

The TSSOP packages are relatively easy for hand soldering. And there are special adaptor boards like Schmartboard for TSSOP and TQFP packages to DIP.

[Tesla DeLorean]

You could always unsolder and remove the LEDs

​The other alternative is to have a header allowing the connection of the battery and jumpering the circuit attachment and modification, so changing back and forth is more practical.

Perhaps you can work with someone with better SMT soldering skills and equipment​