SBus-Output: potential misconfiguration

[wimalopaan]

Setting a UART to SBUS-output via GUI or CLI is useless until setting serial_protocol = SBUS oder SBUS_PWM.

Refer to #11429

Assuming that two UARTs can both output SBUS at the same time, lead me todo something like teh following:

serial 0 4194304 0 0 0 0
serial 1 4194304 0 0 0 0

This is also reported back as valid, so it should work one would think:

serial

serial 20 1 115200 115200 0 115200
serial 0 4194304 0 0 0 0
serial 1 4194304 0 0 0 0
serial 2 0 115200 115200 0 115200
serial 3 0 115200 115200 0 115200
serial 4 64 115200 115200 0 115200
serial 5 0 115200 115200 0 115200

But unfortunately only UART1 (serial 0) is configured to SBus (the code searches in ascending order an stops on first match).

I think at least the CLI serial should report the correct configuration in effective use.

[sensei-hacker]

Yes, one would normally want to set server output as either sbus or sbus_pwm to have them output as sbus. Then the port setting determines which uart is used.

If there were only one option, just sbus without sbus_pwm, one might think that setting the port should imply sbus. But there are two options, and sometimes a user may want to turn it off.

This is similar to you can define which port your GPS is connected to, and when flying indoors turn off the GPS, without losing information. You can then re-enable it when outdoors without needing to disassemble the aircraft to trace the wires and figure out which pads it's connected to.

Also, you set which port your receiver is connected to, then set which type of receiver. Or which type of rangefinder, etc.

Because sbus is one-way communication, one could say there would be no point in duplicating exactly the same information on multiple UARTs. That would just be wasting UARTs. If you want two servos to get exactly the same signal, you can connect them to the same pad / wire.

[wimalopaan]

I see your point: in this case MSP and CLI should refuse to set more thant one UART to SBUS-Out.

The GUI could set a false-config flag, and the CLI could report an error.

[sensei-hacker]

Yeah recently I added a warning in Configurator if the user sets more than two ports as MSP.
The same pattern could be used here.

[wimalopaan]

Yeah recently I added a warning in Configurator if the user sets more than two ports as MSP.

Which PR?
Would be good if the CLI warns too.

[sensei-hacker]

iNavFlight/inav-configurator#2436

It wouldn't hurt to generalize it; something like:

const maxPorts = new Map([
  ['msp', 2],
  ['sbus', 1],
  ['receiver', 1],
...
]);

for (const [protocol, max] of maxPorts) {
  if ( usedPorts.get(protocol) > maxPorts.get(protocol) ) {
    portsWarningModal.innerText = `Too many ${protocol} ports`;
     portsWarningModal.open();
  }
}

[sensei-hacker]

But thinking about it now, maybe the limit for most UART functions is one? Maybe it could default to 1, without listing each protocol.
Only if maxPorts.get(protocol) is defined then use that number instead of 1.

[wimalopaan]

Technically the limit of the output-only protocols is the number of free UARTS. The limit for the input-protocols (like MSP, telemetry, ...) may depend, for MSP this is actually 2, maybe more if the user is knowing what he is doing, for others it might be strictly 1 because of internal race-conditions or ... I am not enough familiarized enough with INav.

But implementing this logic in two places (GUI and CLI) is not a good idea. Better implement that only in an "paramater-validator" in the firmware and let MSP report an error to the GUI. But this maybe a big code chance that affects may parts.

[walll-es]

I ran into this problem! I bought the F4V3S Plus Flight Controller Sp Racing board and re-flashed the INav firmware, setting SBUS to UART 6, but in the receiver tabs, only the first four channels respond. All the other channels show 1500 and don't respond to changes! I tried changing the firmware ports, selecting other boards (OMNIBUSF4, OMNIBUSF4V3, OMNIBUSF4RO, etc.), and changing the protocol to CRSF! I also installed different versions of Betaflight! But the rxrange command returns a list of four channels:
rxrange 0 1000 2000
rxrange 1 1000 2000
rxrange 2 1000 2000
rxrange 3 1000 2000

When I try to add channel rxrange 4 1000 2000, I get an error! My SBUS signal is fine. All 16 channels are available. The signal is fully compliant with standards. I checked it with an analyzer. How can I configure more than 4 channels, or is this a firmware issue?

Я столкнулся с такой проблемой ! Я приобрёл плату F4V3S Plus Flight Controller Sp Racing и перепрошил INav насторил SBUS на UART 6 но на вкладки приёмника увидел реакцию только первых 4 каналов все остальные каналы показывают 1500 и не реагируют на изменения ! Я пробовал менять порты прошивки выбирал другие платы (OMNIBUSF4, OMNIBUSF4V3, OMNIBUSF4RO, ... ) в списки менял протокол на CRSF ! Также ставил разные версии Betaflight ! Но по команде rxrange выдоёт список из 4 каналов
rxrange 0 1000 2000
rxrange 1 1000 2000
rxrange 2 1000 2000
rxrange 3 1000 2000

В попытке добавить канал rxrange 4 1000 2000 выдаёт ошибку ! У меня всё в порядке с сигналом SBUS все 16 каналов доступны сигнал полностью соответствует стандартам проверял анализатором ! Как мне настроить больше 4 каналов или эта проблема с прошивкой ?

[sensei-hacker]

@walll-es
It sounds like you are talking about Sbus input, which is unrelated to this topic.

For your problem, the radio is probably not set up with which switch or slider should control which channel.

You asked "is it a firmware problem"?
No, Sbus is not broken in both INAV and Betaflight. 😄 The switches just aren't configured correctly in your radio.

if your radio is running OpenTX or EdgeTX, there is a screen available that shows the channel values being transmitted. Those are controlled by the mixer section in the radio.

[walll-es]

I simply couldn't find the right thread to ask this question! I'll repeat: the SBUS protocol is working fine, all 16 channels have been checked with an analyzer! Everything is exactly as described in the protocol! I also tried CRSF, and the same thing happened! But the rxrange command only displays a list of 4 channels! I even tried to feed it directly from the SBUS remote control, and it made no difference!

[sensei-hacker]

I simply couldn't find the right thread to ask this question!

If you have a new issue, the best thing to do is to press the "new issue" button. The only colored button on the page, right up there ↗️
Then fill in the template so we have the relevant information to talk about your issue. Rather than hijacking discussion of something unrelated.

If you fill in the template with the relevant information, we might find out things like which receiver you are talking about. If we find out you're talking about ExpressLRS, we would immediately know what your problem most likely is. We would know that you probably have Hybrid mode selected, which sends only eight channels.

Now back to discussing the sbus servo output issue.

[sensei-hacker]

Technically the limit of the output-only protocols is the number of free UARTS

Is that true? Can you set four sbus outputs and it works?