PWR EN functionality about ttgo-t-display HOT 13 OPEN

ESP32-TFT(6-26).pdf
For understand PWR_EN functionality you can have a look on comments, which I made in attached schematic.
So you can set PWR_EN to "1" and read voltage in BAT_ADC, if this voltage more than 4.3 V device have powered from USB. If less then 4.3 V - device have power from battery. To save battery you can set PWR_EN to "0" and in this case USB converter will be power off and do not use your battery. When you need to measure battery voltage first set PWR_EN to "1", measure voltage and then set PWR_EN back to "0" for save battery. I hope my descrition will help somebody to better use this device! :)

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It's possible to solder a wire on the bottom of the T-Display module to access the GPIO14. I didn't test it myself but a user confirmed it to work ( #6 (comment) ) :

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Yes, it's possible to solder a pin on one end of the diode that's connected to IO14 and use JTAG. I did it with ESP-prog and it worked. Not needed to remove the diode, but I'm not using it with battery, just to debug.

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Just a guess: maybe it is read only? So you can read the value and let your sketch find out in this way whether it runs from battery or USB power?

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@Joennuh its an output, there's a diode on the pin, restricting current flow to one direction.

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I have the same problem. I've been analyzing the scheme but I can't figure out how that pin works. I think the scheme contains errors in the polarity of the mosfet.

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I get feedback: PWR_EN can continue to detect the power of the lithium battery when there is no USB power supply. V3V is to prevent leakage current. @paccerdk

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@lewisxhe
This isn't making much sense to me.
Detect in which way? As mentioned earlier, it appears to be an output, there is a diode restricting the current flow to one direction. (out)
Could you perhaps share the feedback that you got?
Honestly, it seems to me like there is a mistake on the schematic, and the PWR_EN was supposed to be able to let the device turn itself off, when battery powered. that also explains the naming.

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@paccerdk
In order to use VBA to turn on the power, because, when downloading 32, the single chip PWR_EN can not work, so V3V has no power, so 2104 can not be downloaded, so open V3V power through VBUS

The above is the original words, I am responsible for the transmission.

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I cannot understand BAT offsheet. It is just connected to Q4 and to the partition for battery conversion... Is it connected also to VBAT?

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@ticksp Thanks for the clarification. So the connection of GPIO14 to PWR_EN (as it is JTAG's TMS pin) does not hurt JTAG functionality right?
The way I see it, while debugging via JTAG, some transistors would get stressed (because of PWR EN) and the "BAT_ADC (ADC_IN, VDET_1/GPIO34)" voltage is not to be trusted, but nevertheless, this wouldn't hurt debugging.
#17 #26
Edit: Oh, I think the problem is GPIO14 is not actually broken out so it's inaccessible...

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Can anyone confirm that you can access IO14 at D6 in order to support JTAG and have the JTAG work?

Also it seems as if from ticksp's comment above:
When you need to measure battery voltage first set PWR_EN to "1", measure voltage and then set PWR_EN back to "0" for save battery.

if not using a battery then D6 be removed and this makes it easier to solder a wire to the anode pad of D6?

from ttgo-t-display.

Yes, it's possible to solder a pin on one end of the diode that's connected to IO14 and use JTAG. I did it with ESP-prog and it worked. Not needed to remove the diode, but I'm not using it with battery, just to debug.

Thank you for that confirmation.

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