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Partial telemetry loss after arming

Hi all,

I’m having an issue with SiK-based radio telemetry on ArduCopter 4.0.4 and multiple GCS softwares.

In summary, as soon as the aircraft is armed, parts of the telemetry stream appear to freeze and no longer update for the duration of the flight (until the aircraft is powered off). Most of the time, it’s the HUD that freezes (attitude stays locked level, altitude, speed, vsi all read zero and don’t budge), but I’ve also seen battery information freeze with the HUD still moving, and in once instance a complete loss of telemetry.

Unfortunately, I’m somewhat restricted in my ability to post raw log files, but I’d be happy to provide screenshots and as much info as I can on request. This has been reproducible for me on multiple aircraft, multiple GCS laptops, Mission Planner and APM Planner 2, and every combination of those things.

Some things I’ve wondered about:

  • Telemetry radio temperature limits. It’s quite cold in my location, and I do see the issue happening outside reliably. I’m using the Holybro v3 915MHz modules. However, it also happens indoors in a heated environment (50+ F)
  • Outdated radio firmware. Used MP to update to latest SiK firmware, no change.
  • Mission Planner issue. Eliminated in my mind - happens on APM Planner 2.0, on at least 3 different computers (with both software packages). MP version 1.3.74 build 1.3.7563.27684; APMPlanner version 2.0.26. Windows 10 on all machines.
  • Hardware failure: happens on 2 different aircraft with 3 different Cubes (Black). One acft has had its cube for quite some time now with no issues, one got a replacement due to an unrelated issue; telem loss occurred on both old and new fresh-out-of-box Pixhawk. I’ve also tested multiple (at least 3) different telemetry radio units on the ground side.

I believe it may be related to the SR0_* parameters. I did mess with some of the stream rates in MP a while back, but didn’t notice this issue then - I’ve now put them all back to default, and still get nothing. Mission Planner’s tuning window also supports this hypothesis - I can see roll and pitch targets, but the actual roll and pitch lines freeze along with the HUD.

Has anybody else had this happen? If so, how (did) you fix it?

Thanks!

Can you post your parameter file?

I wish I could, but I can’t give the whole thing. I can, however, post a list of the parameters that are related to this (please let me know if I’m missing some, I am by no means an expert :slight_smile: ):

ADSB_ENABLE = 0
BRD_BOOT_DELAY = 0
BRD_SER1_RTSCTS = 2
SERIAL0_BAUD = 115
SERIAL0_PROTOCOL = 2
SERIAL1_BAUD = 57
SERIAL1_OPTIONS = 0
SERIAL1_PROTOCOL = 1
SR0_ADSB = 0
SR0_EXT_STAT = 4
SR0_EXTRA1 = 8
SR0_EXTRA2 = 8
SR0_EXTRA3 = 2
SR0_PARAMS = 0
SR0_POSITION = 2
SR0_RAW_CTRL = 0
SR0_RAW_SENS = 2
SR0_RC_CHAN = 2
SR1_ADSB = 0
SR1_EXT_STAT = 0
SR1_EXTRA1 = 8
SR1_EXTRA2 = 8
// all other SR1_ parameters are 0
// all SR2_ and SR3_ parameters are 0
TELEM_DELAY = 0

I’ve also been disabling ECC and flow control (RTS/CTS) on the SiK radio settings page, as it makes the initial parameter download about 4x faster. The air speed is set to 250; other than those three, all the SiK setting are default.

Thanks!

I would try
SERIAL1_PROTOCOL = 2
And in Sik radio settings, set airspeed to 64 and baud to 57.
That crazy-high airspeed is not required for 57k baud, only a little bit of overhead is required (64k airspeed).
You can also try this:
BRD_SER1_RTSCTS,0
so you’re not relying on the default “auto” setting to figure out the RTS/CTS activity.

1 Like

Shawn,

That seems to have fixed it for me! I’m not quite sure which parameter did the trick, but I tested those three changes and now seem to have good telemetry after arming. I’m not sure why, but for some reason I never put 2 and 2 together to figure out that the airspeed of 250 meant 250k, not just plain old 250 bit/sec.

Thank you!!

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