New FrSkyX protocol

Hello,
Test Ver. 8af

i combined the Failsave with the SBUS Test

Failsave does working good on all 12 Channels. On RX Blackout the Failsave need 2-3 Sec to get saved. If i switch RX off and on, then without waiting 2-3 Sec TX off the Failsave does not do his job.
The SBUS does not work on Channel 5 to 8, The Servo do some Noise but not useful moving
SBUS 1-4 and 9-12 do a good job with smooth and direct moving

At practical use this delay of Failsave noes not count, but i try it on Taranis tomorrow . The normal way to set the Failsave is with the Button on the RX, only if some one want to fine tune or set it fast with out to pull the RX out of the Plane then the Menu is a nice Feature .
-> The best way to set a Failsave value is to hold the Sticks and save this as Falisave with the Button on RX. Only things like Gear or Motor is better at Menu. Because the Numbers noes not show the actual movement of the Servo.
its more like a Personal taste of the User.

greetings Alex

I thought set the failsave from tx, or to set by using the pinpoint at the Rx, the result should be the same isn't it? It is also possible in D8 protocol. It is just handy as no need to dismantle the rx from the model to set it.

Possibly failsave operation depends on type of Frsky Rx, I had in mind some do have a dual stage, not sure though.
<1sec hold last frame
>3sec move to stored failsave?

The SBUS behavior is curious. Would you please test with failsafe disabled on all channels to make sure it's not interfering?

The failsafe values are only sent every 9 seconds. Maybe I need to send them immediately whenever newly starting to receiving packets? What you describe also implies the failsafe values sent by the tx are not saved in the rx when the rx is powered off - is that normal? I guess that makes sense. You could store values in the rx with the button that will be used if none are being received from the tx. If it does receive failsafe packets from the tx it will use those values until next powered off, but they don't overwrite the button saved values. Is that correct?

Setting the failsafe by stick position sounds convenient. In deviation we could add something to capture current channel values to the channel failsafe, but how would you trigger it?

It's also used by FrskyX now. I think D8 has a similar feature so it's on the list.

Failsave Test
The Button has priority and overwrite the Deviation setting.
If a Channel is not programmed with the Button the Deviation Value is used.
The programmed Failsave value ( with Button) stay so long until a new Bind is done. The new Bind delete the Button Failsave

SBUS , switching the Failsave off noes not change the none working Channel 5-8. On the Test the Servo does go to mid Point but then it does not right move.
-> The RX Channel 5-8 does the same, it does not move the Servo. Only the mid Point PWM is at the Channel output .

greetings Alex

Yep, bug crept in on channels 5-8 when I added failsafe. Should be fixed. Test build is updated.

Thanks for the update on the failsafe behavior. Makes sense the values from the tx are not saved in the rx - the tx is sending them all the time anyway.

DSM doesn't user the channel Failafe values. Instead, The Rxs that have failsafe tend to set it at bind time. So the DSM protocol delays after bind so you can set things and then hit enter.

Test build updated with a change that may help the telemetry recover after rx blackout.

@hexfet
Where is the packet[21]=0x80?
if ((pkt[5] >> 4 & 0x0f) == 0x08) { // restart or somesuch
- seq_last_sent = 0x08;
- seq_last_rcvd = 0x00;
+ seq_last_sent = 0;
+ seq_last_rcvd = 8;
packet[21] = seq_last_sent << 4 | seq_last_rcvd;

Hello,
Test Ver.c59

Channel 5-8 is working now. Failsave on all Channels ok.
Telemetry does not work.Switching of AD2GAIN does not enable the Telemetry, the only displayed Values are Volt1 and RSSI.
greetings Alex

Because It sends out only 0x08 and block telemetry.As I said before if the packet[21]not reach 0x80 telemetry don't start.

I understand setting failsave from TX, all channels current positions are stored in the RX? Basically no difference between set failsave by pin button at Rx or set fromTx, is that assumption correct? Or will the during flight failsave get lost at power cycle the receiver?

In any case I can confirm, when I set my failsave from Frsky DHT-U Tx module (What they call during flight), then switching of the Tx, my servos will move to Failsave position.


Failsave as described Frsky for DHT-U D-Series

---

In some circumstances, such as strong interference, the radio signal may be lost. By default, when the signal is lost the receiver will keep the outputs set at the last received positions while it continues to try to search for the transmitter. Normal operation will resume once the signal link is regained.

Failsafe is a mode that allows pre-setting of channel positions that the receiver will use, instead of the last known positions,for such a case as losing signal.

• Follow the steps below to set failsafe BEFORE flight:
Option-1. How to set failsafe to a user-determined state on lost signal:
1) Bind the receiver to the transmitter module first and turn on both the transmitter and the receiver;
2) Move the controls to desired failsafe position for all channels;
3) Press briefly the F/S button on the receiver and you are done.

Option-2. How to set failsafe for no pulses on lost signal:
1) Just press briefly the F/S button on the receiver while the transmitter is off and you are done.

• Follow the steps below to set failsafe DURING flight:
1. Bind the receiver first and turn on both transmitter and receiver;
2. Enter MENU page, select F/S to enter failsafe sub-page, press Button B to set failsafe at the desired failsafe position DURING flight.

---

midelic wrote: @hexfet
Where is the packet[21]=0x80?
if ((pkt[5] >> 4 & 0x0f) == 0x08) { // restart or somesuch
- seq_last_sent = 0x08;
- seq_last_rcvd = 0x00;
+ seq_last_sent = 0;
+ seq_last_rcvd = 8;
packet[21] = seq_last_sent << 4 | seq_last_rcvd;

You're right, this change was a mistake. Thanks for the review The test build is updated with this change reverted.

There is still new code to restart the sequence counters if rx packets are missed. So it's worth testing if telemetry recovers.

Fernandez wrote: I understand setting failsave from TX, all channels current positions are stored in the RX? Basically no difference between set failsave by pin button at Rx or set fromTx, is that assumption correct? Or will the during flight failsave get lost at power cycle the receiver?

What Alex reported was that the tx failsafe values are not saved when rx his powered off. However

2. Enter MENU page, select F/S to enter failsafe sub-page, press Button B to set failsafe at the desired failsafe position DURING flight.

this is new to me. My impression was the failsafe values are sent from the tx continuously. If you press Button B, are the failsafe values retained in the rx after the rx is powered off? If you don't press it, does the rx still follow the tx failsafe values until the rx is pwered off? Is there a similar button in the Taranis failsafe menu?

From Taranis manual.

Step 5: Set Failsafe mode
There are 3 failsafe modes: No Pulse, Hold, Custom.(My note" selectable from Model setup menu)
No Pulse: no pulses output on lost signal, just choose, wait 9 seconds before the failsafe takes effect, and
you are done.
Hold: hold the last positions before signal is lost, just choose, wait 9 seconds before the failsafe takes effect,
and you are done.
Custom: pre-set to required positions on lost signal. Move the cursor to “Set” and press ENTER, you will
see FAILSAFE SETTING screen below. Move the cursor to the channel you want to set failsafe on, and press
ENTER .When moving the corresponding sticks or switches, you will see the channel bar moving. Move the
channel bar to the place you want for failsafe and long press ENTER to finish the setting. Wait 9 seconds
before the failsafe takes effect."

So you should wait 9 seconds and see the rx take the FS values or not.If Tx powered down in less than 9 seconds it is obvious what happens.

Interesting. It sounds like we're currently doing Custom mode. Wonder how we tell the rx to do No Pulse or Hold? Having to wait 9 seconds implies it's just something sent in the regular failsafe packets. Maybe a special channel value, but that doesn't seem right because all values are valid channel settings.

One of either No Pulse or Hold could be selected by not sending any failsafe packets maybe. Alex, how does the receiver behave during failsafe if all the Deviation channels have failsafe disabled?

Fernandez' post describes a way to set No Pulse on the receiver with the F/S button. Is there also a way to set the mode back to Hold?

You can see exactly which or what in OpenTX source code PXX protocol pxx_arm.cpp.You can see there what is send out and how.
edit:
I should have followed my advice before.

I can test failsave for you by tonight, I can only test it for D series receivers. I am not 100% sure if I repower the Rx, if values are stored permanently..... (If not I have always been flying without failsave)


I always had in mind failsave from tx was just, a command bit, etc. When receiver receives this failsave command over the air, it just stores the current transmitted channel values same as if failsave button at Rx was pressed.

Will check and let you know.

Hello,
Test Ver.7ef

Telemetry does restart on Blackout of RX with fast recovery Time. The same on restart of the TX. It works good !
Failsave:

-The programmed Failsave stay so log until RX does Power Cycle, if the Menu Failsave was set to OFF you have to Power Cycle the RX to delete the Failsave Value.
-The Failsave programmed with the Button on RX stay until a new Bind (the Bind reset the Failsave) and it overrides the Deviation Failsave Value if it is programmed.

On most of the RX Equipment are 2 Modes of Failsave (i used manny Brands of 35 Mhz and 2,4 Ghz).
1st is the Hold Funktion, if the RX does not get a Signal it holds the last Stick Position until it recover or you get impact on Ground (most Pilot use this. On short Signal loos the Plane Fly his normal way)
2nd is the Failsave programmed . This force the Servo to the Programmed Point.

Most standard from Factory is a mixed Setup of booth. The Engine Channel is always set to 0 on loosing Signal and the Servos going to hold of the last Stick Pos.
The Time of setting the programmed Failsave does a bit vary , Most it uses 1 Sec. Hold and then a Forcing to the programed Pos. This is the best of two Worlds. If you get a short Glitch then your Plane does not Wild things. But if You have a total loosing of Signal , then your Plane goes into loosing Alt and hopefully soft landing without Control
Most of the Systems without a programable Failsave does switch the Engine Channel to 0 to stop the Engine.

-> some External Failsave Systems does need an Indicator of the State from the RX, here is the little Trap how to submit it to the Flight Controller . Old Systems use the PWM ( if there is no Signal, then there is a Signal loos). I think the most of the new one can be programmed to some Value of the Channel to indicate a Signal loos, here is a non needed Channel set to a known Point on Failsave and the Flight Controller use this Point to indicate a Signal loos.

greetings Alex