3V3 output not working

[Sleepy_Reenigne]

Hi,
Looking for some guidance.
The 3.3 V output has worked before but now only outputs 0.12 V
The board is running fine, and the following code is used:

from machine import Pin
threevthree = Pin('EN_3V3')
threevthree.value(1)

I'm powering it with 3.4 V on Vin but have also tried from USB.

Any help would be much appreciated - I may be missing something obvious!

[pythoncoder]

That is odd. I use

Code: Select all

from machine import Pin
Pin.board.EN_3V3.value(1)

but that's the same as your code. I fear you may have zapped U10, the switchable LD39130S 3.3V regulator. Is it possible that a voltage was applied to the 3.3V output at some time?

[Stevo52]

@ pythoncoder I have nearly done that myself, but being cautious I read the docs just in time.. it would be an easy thing to do!

[Sleepy_Reenigne]

Thank you both, I agree it seems to be that I've blown it. Not sure how though as the PCB I've made that it connects to has (I believe) appropriate protection diodes.

When I tried a friends Pyboard D on the same PCB the output drops to around 0.5 V, but returns to 3.3 V when disconnected. I think it must be getting current limited - could this have caused mine to blow?

[pythoncoder]

The LD39130S datasheet claims "internal current foldback and thermal protections" so a short to gnd should not blow it up. But shorts to other voltages might. I'd check that PCB very carefully indeed...

When I tried a friends Pyboard D on the same PCB

You have a very trusting friend

[jimmo]

from machine import Pin
threevthree = Pin('EN_3V3')
threevthree.value(1)

I'll need to check, but I think you also need to put the pin into output mode.

Code: Select all

from machine import Pin
threevthree = Pin('EN_3V3', mode=Pin.OUT)
threevthree.value(1)

[Stevo52]

This might not be the 'correct way' but on V1.13 on SF2W and SF6W PYBD's I just use:

Code: Select all

import machine 
machine.Pin('EN_3V3').on()

Short and simple and it works for me