Ideas: T-Beam powering issue

[Nigel Bray (SoftRF)]

May I ask if there are any clues with the T-Beam power on reset, reset switch or decoupling that I could fiddle with to restore operation?

My T-Beam fails to power up properly with a 3.8V regulated supply to the LiPo battery terminals (battery removed).

Is has worked before and nothing I know has changed!

It works with a 4.2V cell attached.

Best regards Nigel

[Moshe Braner]

Nigel:  when you say "fails to power up properly with a 3.8V regulated supply to the LiPo battery terminals (battery removed)" do you mean it does not boot up when the power source is turned on?  What if you press (and hold for a second) the pushbutton (next to the USB connector) (or click the reset button)?

And by "It works with a 4.2V cell attached" do you mean boots when you insert the cell, or click the button?

What happens if you connect USB power?

[Nigel Bray (SoftRF)]

Dear Moshe,

Yes,  it does not boot up when the power source is turned on..

If I press (and hold for a second) the pushbutton (next to the USB connector) (or click the reset button), nothing happens.

Yes, it boots when I insert the cell, or click the button.

I have disturbed something in my previously working setup and it is not obvious what!

Before I touch the wring in my panel, I'll investigate if I can power it and get the comms to the ERA80 vario working again with the existing wiring.

I wonder if my choice of 3.8V to the cell terminals was unwise, but seemed to be logical as I have removed the cell holder and it is a nice big pad to wire to.

Best regards Nigel

[Moshe Braner]

3.8V to the battery terminals (with no battery) is OK.  I suspect your 3.8V source has died.  Even if it shows 3.8V with the T-Beam not running, maybe it cannot supply the needed current to start it.  Test it with a voltmeter and a constant load (e.g., a resistor of 10-20 ohms).

[Rob Youngs]

Hi Nigel, FWIW, I found that with ESP32's in general that if PSU voltage does not rise fast enough it can freeze the ESP

--
You received this message because you are subscribed to the Google Groups "SoftRF_community" group.
To unsubscribe from this group and stop receiving emails from it, send an email to softrf_communi...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/softrf_community/00fe1db6-fc19-4fda-ad6d-236c3312d8d1n%40googlegroups.com.

--

Mob: 07980 750216

[Nigel Bray (SoftRF)]

Dear Moshe,

On Monday, July 6, 2026 at 2:51:44 PM UTC Moshe Braner wrote:

3.8V to the battery terminals (with no battery) is OK.  I suspect your 3.8V source has died.  Even if it shows 3.8V with the T-Beam not running, maybe it cannot supply the needed current to start it.  T

 

Yes, something changed there, and now the PSU voltage does not rise fast enough as Rob mentioned as well.

Thank you!

Best regards Nigel

[Moshe Braner]

Things are more complicated on the T-Beam (versions 1.x) since it has the PMU chip (AXP192 or AXP2101).  The 3.3V power for the ESP32 comes from the PMU.  The button next to the USB port talks to the PMU, not the ESP32.  Sometimes I try to turn on a T-Beam and the red LED lights up but not the blue one.  The red LED means 3.3V power is output by the PMU.  The blue LED is controlled by the PMU, but in response to commands sent by the firmware running on the ESP32.