Serial passthrough is broken

[andyp1per]

Bug report

Following the serial passthrough guidelines on the wiki for GPS does not work on 4.2.x or 4.3.x. A connection can be established but no data appears to flow.

Version
4.2.x, 4.3.x

Platform
[X] All
[ ] AntennaTracker
[ ] Copter
[ ] Plane
[ ] Rover
[ ] Submarine

Airframe type
What type of airframe (flying wing, glider, hex, Y6, octa etc)

Hardware type
What autopilot hardware was used? (Pixhawk, Cube, Pixracer, Navio2, etc)

Logs
Please provide a link to any relevant logs that show the issue

[IamPete1]

#20977

[mbuzdalov]

Seems to be there for quite a while. With a JHEMCU GSF405A board, I was trying to flash a ELRS module, which is hardwired to SERIAL1, using passthrough, to no success. I though this is me who fails, but apparently not.

[andyp1per]

@bugobliterator any update on this?

[teodoryantcheff]

Anything?

[teodoryantcheff]

Almost a year later, have any changes been done to the serial passthrough code?

[rmackay9]

I've added this to the Copter-4.4 issues list so it won't be forgotten.

I think serial pass through works in some cases at least because I used it a few weeks ago... so I suspect this issue is just for GPSs.

[teodoryantcheff]

Thank you, @rmackay9 !
I think this is not limited to GPSes only, since as you can probably see in the "attached" video, back when I was testing this, a "GPS" is completely not involved in reproducing the issue reported.
Or, of course, there's something that I may be completely missing in the bigger picture.
Anyway -- many thanks, again!

[rmackay9]

So this really is a problem and we've got a fix for master (aka "latest") that we will backport to 4.4 for sure and possibly 4.3 if we ever do another release of 4.3.

[rmackay9]

@andyp1per,

How do you feel about closing this now?

[andyp1per]

I haven't tried it but I trust @tridge - happy to close