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Xinyuan-LilyGO / LilyGo-LoRa-Series

LILYGO LoRa Series examples
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T3S3 v1.2: No USB Power Output on USB OTG Host mode (Power via Battery JST only) #178

Open joyel24 opened 6 days ago

joyel24 commented 6 days ago

I would like to use the T3-S3 USB-C port as a USB OTG Host. Data+/Data- appears to have proper communication but +5V is outputting 0V so it cannot power anything...

Is there a simple way to enable +5V output on USB-C ?

I searched a bit in the pcb, for the moment, the best option I found is to solder a little wire from 5VBUS to this side of this tiny tvs diode witch appears to be connected to the USBC 5V port:

BUT is there a better way to have +5V on USB-C port, or is there a better place to easier solder a wire

2024-06-22 23 20 56

lewisxhe commented 2 days ago

If you do that, the battery voltage will be directed to USB-C. If you plug the USB-C into the computer at this time, it is equivalent to connecting the battery to 5V. This is dangerous behavior. In addition, the battery can only provide a maximum voltage of 4.2V (when fully charged) and cannot provide a standard 5V for USB devices. I do not recommend using it this way.

joyel24 commented 2 days ago

Finally I did it another way, instead of using onboard JST battery, I soldered USB A cable to a GND and the + to the diode I already mentionned.

This way I can power the T3S3 with any USB power source, and If I connect a device to the USB-C port of the board, it powers the device attached to it, so for the moment I'm doing like this. I'm losing efficiency but it works well. it way also eliminates possible troubles about battery over-voltage.

I note that the voltage is a bit high for a li-ion cell but generally datasheets are talking about changing voltage of 4.20V±0.05 so a range of 4.15-4.25V witch is the case here 👍

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moshe-braner commented 1 day ago

I wish the LilyGo boards (T3S3, T-Beam, etc) would have a solder terminal that connects to the 5V USB power. For purposes such as this. Or in general to be able to supply 5V power to the board without using a USB connector. For example, I have powered some T-Beams from a 12V-5V converter that does not have a USB connector, how to attach it to the T-Beam is a problem. Also, the existing solder terminal that is marked "5V" should not be marked that way, since that is not what it is!

joyel24 commented 1 day ago

I wish the LilyGo boards (T3S3, T-Beam, etc) would have a solder terminal that connects to the 5V USB power. For purposes such as this. Or in general to be able to supply 5V power to the board without using a USB connector. For example, I have powered some T-Beams from a 12V-5V converter that does not have a USB connector, how to attach it to the T-Beam is a problem. Also, the existing solder terminal that is marked "5V" should not be marked that way, since that is not what it is!

I agree, I think there is a bit of improvements that can be made for future version of PCB to power an USB device to it while running on battery. It could be a little DC-DC converter switchable like in the flipper zero for example. You can enable 5V output when you want but it's not enabled by default to draw less power probably.

moshe-braner commented 1 day ago

Powering an external USB device while running on battery would, as you said, require additional hardware, another DC-DC converter. That may or may not be not worth adding to the basic board, increasing its cost for a rare type of usage.

What I requested was just a solder terminal on the board, that is connected directly to the power pin of the existing USB jack. That would cost nothing, just a small change in the design of the PCB.

For the purpose of powering an external USB device, it could then be done by using an external 5V power supply through that added solder terminal. That by itself would not allow extended standalone battery-powered operation of the pair of devices, though.

I have set up a solar-powered system with a T3S3, a small solar panel, and an external DC-DC converter the takes the solar panel output and converts to 5V which is fed to the USB jack (and it would have been easier if there was a true 5V solder pad). A USB OTG device could be powered by that either by a connection to the solar 5V source (can use an OTG Y cable) or by removing the battery from the OTG device and powering it instead from the solder tab currently marked "5V" - which is really about 4V - connected to the battery terminal (not the USB jack) of the external device.

joyel24 commented 23 hours ago

Yes, just an available pin connected to 5V of USB port can be enough. It can be anywhere in the board but it will be way better than doing like I did.