[Bobrcnut]

...Trying to set up a Bluetooth connection between a smartphone and a CC3D, getting a solid green Bluetooth icon but no data transfer, the '4 squares' icon is blinking red, advising me to try reducing Bluetooth BAUD rate.  My question:  the documentation says that the smartphone must have OTG capability.  Does that requirement apply only to USB connections, or is it also required for Bluetooth connection?  The same Bluetooth adapter works fine with INAV and an SPR F3 F/C.

[f5soh]

OTG will be related to USB, when you plug a external device to your phone.
Baudrate set in CC3D Main/FlexiPort should match the baudrate set in Bluetooth module you connect to the CC3D.

[Bobrcnut]

Thank you for the quick confirmation.  B/T unit is connected via Main Port, and both the port and B/T unit are set for 57600.  The odd thing is that the packet counters on the LP2Go screen show no data transferred in one direction, and in the other direction the number keeps changing both up and down.  I don't recall which is which, I'll re-try tonight and add more details here.  Same symptoms on two different smartphones, an LG G5 and a Samsung Galaxy J3.  Different symptoms when connecting to the PC-resident GCS... B/T unit is paired, and connects to Windows OK, but changes from Connected' back to 'Paired' a few seconds after the GCS shows 'Connected'.   I have another B/T unit on the way just in case, but as previously noted, this one works perfectly when connecting an F3 FC to the INAV GCS.

[Bobrcnut]

I believe I have resolved this issue, but I need to test both the CC3D and the Revo using both the Bluetooth connection to both smartphones and the Bluetooth adapter connection to LibrePilot.  I'll be back tomorrow with details after further testing.

One quick question, though:  On the Librepilot GCS Input screen, when I move the Tx sticks, the stick position indicators do not smoothly follow the stick movements.  Instead, there's a short delay and then the position indicators jump quickly to the new position.  Is this normal?  (I've been an INAV user for a long time and I'm used to seeing the pointers move immediately and smoothly across the screen, exactly following the stick movement.)

[f5soh]

Default refresh is slow (2s), assuming we can use the telemetry with OPLink.
You can reduce the "Flight Telemetry Update Period" to 300ms if you want smooth Inputs.
Click the button with the big eyes and check the "Show metadata" in Options
Change refresh value for ManualControlCommand UAVO and save using the HDD button with red arrow.

[Bobrcnut]

After much testing, this is in fact resolved.  It was due to a poorly/improperly crimped connection in the cable connecting the BT unit to the CC3D... the BT TX-to-CC3D Rx connection was intermittent, thus the different symptoms. That cable was included with one of the BT units.  The problem did not occur on my original OPCC board because it's not installed in any airframe and thus did not require bending or stressing the cable.

F5soh: thank you for clearing up the 'stuttering' input indicators.  It is really not a problem, it was just that the same behavior in INAV and other configurators sometimes indicates an overloaded CPU on the F/C board.