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FrSky X-lite Pro OTX2.3.9

USB connection to PC

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Martin_K02/07/2020 21:12:29
177 forum posts

What should happen if a powered on Taranis radio running OpenTX is plugged into a PC USB port?

Am I correct to expect to see two drives mount, the radio plus it's SD card?

In radio setup I can choose Ask, Joyst, SDCard for connection to USB.

If Ask is selected I am prompted to choose between USB Joystick (HID) and USB Storage (SD). Selecting HID returns me to the two option menu. Selecting SD brings up "failsafe warning", I hit the exit button which brings me back to the two option menu. I am then in a loop until I disconnect the USB cable. The colour of the flashing power LED changes during the process. Examination of "dmesg" (Debian GNU/Linux) tells me;

usb 2-4: reset SuperSpeed Gen 1 USB device number 2 using xhci_hcd

If I take away the option and set USB behaviour to SDCard, as expected I don't get a prompt to choose, just the "failsafe warning", (which I assume is behaviour as when returning to normal radio operation - I have not yet configured failsafe on my one model), then stuck in a loop until I disconnect the USB cable.

Clearly the radio responds to the connection of the USB cable but whatever is supposed to happen next fails. What is supposed to happen next?

Martin_K03/07/2020 09:24:09
177 forum posts

USB usage on the Taranis X-Lite Pro

I think the problems I am seeing relate to X-Lite Pro battery charging via USB and variations in capabilities of USB hubs.

I was working with the radio connected to my desktop PC (Intel NUC) via USB hub in the monitor (BenQ). A USB over-current condition warning from my OS (Debian) prompted me to stop using the NUC. I have a very old laptop (Acer, also running Debian), that I am less woried about damaging so transferred work to that.

I had only consciuosly charged the radio's batteries once so far, before initial use, radio off and connected to PC USB with the PC in 'suspend' mode, so not being used by me at the time. My assumption from the minimal information in the Taranis X-Lite S/Pro manual was that the batteries charged when the powered off radio is connected to USB. I now realise the batteries are charging any time the radio is connected to USB, whether off, on in bootloader mode, or on in normal mode. I say this after noticing the displayed radio voltage was increasing while I was testing.

Using the laptop things that failed on the NUC now worked, e.g. mounting SD card volumes, connecting the radio in HID mode for use as a simulator controller. My guess is the Intel NUC / BenQ hub could not cope with the current draw from the charging batteries and operate the radio's USB interface at the same time. When I initially flashed the radio with new firmware on the NUC, which worked, the batteries were freshly charged so prpbably drawing minimal current from the USB port. After fully charging the batteries via the laptop a quick, partial, test with the radio connected directly to a NUC port (not convenient) looks better.

I am not going to further document this here, probably the wrong forum, so will finish with the observation that the original X-Lite did not incorporate battery charging. Adding it looks like a bad idea as I see no easy way to disable it in the event it causes problems.

Bob Cotsford03/07/2020 09:29:34
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8650 forum posts
483 photos

Martin, does the X7 use the same socket both for charging and for connecting to a PC? All the FrSky trannies that I own use separate sockets for the two functions. Interesting that they've gone down that route with the smaller Txs.

Martin_K03/07/2020 09:53:50
177 forum posts
Posted by Bob Cotsford on 03/07/2020 09:29:34:

Martin, does the X7 use the same socket both for charging and for connecting to a PC?

Bob, yes, same socket for charging and PC communications.

I have an X-Lite Pro, which appears to have the same interfaces as the X-Lite S. They have a single micro-USB connector. The LED on the power switch displays different colours/flashes/on and off to indicate what the radio is doing.

Completley new to FrSky and OpenTX my first step was to install OpenTX Companion and get it talking to the radio. When that did not work it confused the hell out of me. I created a model and bound a receiver using the on radio screen which worked giving me some confidence. I can now communicate with Companion too so things are looking better.

I am going out to clear my head!

Martin_K03/07/2020 15:45:32
177 forum posts

Having cleared my head with a cycle ride in 25mph winds, a solution.

A standard USB port cannot supply enough current to charge Li-Ion cells in the shortish time I observed so how can this work? Careful reading of the NUC spec. sheet revealed one of it's USB ports is a 'charging port' which can provide additional current. How do you know which one? Intel do not tell you. The plastic inside the USB connector is colour coded yellow.

FrSky supply a very short USB cable with the radio. I think there is logic here. For charging, the voltage drop in a long cable is a problem.

Rewiring my PC connections (the dust down there!) to get the very short USB cable into the charging port and arranging a space on which to stand the radio, reliable PC to radio comms (No USB error messages so far). Yippee! The true test will be what happens next time I plug in the radio when it's batteries are significantly discharged.

No documentation to explain any of this, you just have to know.

Ron Gray03/07/2020 15:49:36
2235 forum posts
978 photos

I’ve got a 2019 Taranis and that uses 1 port for connecting and charging and I don’t have a problem doing either with it.

Martin_K03/07/2020 15:53:15
177 forum posts

Ron, your USB port must be capable of sustaining suffiicient current. Had I plugged into a different port first time this thread would not exist.

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