Pixhawk PWM input for RSSI (EZUHF)

Gents I need your help.

I recently upgraded one of my 2.6APM powered quads to a Pixhawk.  One of the reasons I went ahead and did this is because the Pixhawk is supposed to take PWM RSSI signals directly (into the Sbus port aka Pin 103) and I could ditch my PWM to analog conversion circuit is used in my APM.

I have verified that my EZUHF receiver is outputting RSSI in PWM form on one of the channels. (it will move a servo appropriately when the RF gets weak or disappears... and it worked fine for the APM as an RSSI input via a PWM to analog conversion circuit)

And, I have hooked up the PWM RSSI output to the Sbus port (pin 103).... it does nothing.  Shows zero RSSI on the OSD no matter what.

I can't find any useful description of how to configure this in the wiki, mission planner or this site.

How do you make a Pixhawk show RSSI from a PWM input on pin 103 as its advertised?

Thanks for your help.

Steve

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Permalink Reply by David m on December 13, 2014 at 9:11am

You have done nothing wrong.

Unfortunately the RSSI is inverted with the EZUHF. 

In the movie you will see that I chose to use Link Quality which is non-inverted and responds to degradation from interfering signals. In my opinion Link Quality is the better choice anyway.

Permalink Reply by Sergio Vial on December 18, 2014 at 7:47pm
I am not sure, but eventually I chose the link quality on chanel 8, so I cannot understand why it shows reversed on the Minim osd, but I will repeat the procedure to be sure before complaint.

Regards
Permalink Reply by Ross McGowan on January 22, 2015 at 1:41am

trying to set this up and I find when I assign EZUHF LQ to channel 8 I lose my flight mode selection

Using the latest APM plane on an APM 2.6

Any clues Gents, this is driving me spare!

Ross

Permalink Reply by David m on January 24, 2015 at 6:17am

I moved my flight modes to a different channel.

Look a about time code 2:17 in this video for the schematic and explanation:

https://www.youtube.com/watch?v=rh7-D96FIK0

Permalink Reply by Ross McGowan on January 24, 2015 at 2:53pm

Thanks David

I have watched your Video a couple of times, very well presented

I am using CPPM and want to keep it that way

My problem is I cannot figure how to switch my Flight mode select channel to anything other than Channel 8 (I'm using Arduplane 3.2)

I note in your schematic you use channel 6, how did you change that from what appears to be the default of channel 8

To confuse the issue more the current setup wiki says to use channel 5 which doesn't work for me

Permalink Reply by David m on January 24, 2015 at 9:09pm

I changed the flight mode channel input from the default 8 to 6 in the mission planner and then wrote the settings to the APM. 

Permalink Reply by Ross McGowan on January 24, 2015 at 10:41pm

Got That

Please forgive my stupidity but I am asking how to do that

What parameter are you changing and where do I find it?

Permalink Reply by Ross McGowan on January 25, 2015 at 12:35am

for the nth time I looked and found it

all good now, many thanks David

Permalink Reply by David m on January 27, 2015 at 4:23pm

Oh! well I am glad you found what you needed.

You would think it would be on the flight mode screen, right? But noooooo way.

Just to recap for others, I changed the flight mode channel under config/tuning under the full parameter list. Look for FLTMODE_CH. (APM must be connected first)

Where did you find it? 

Permalink Reply by Ross McGowan on January 28, 2015 at 2:44am

I had looked in Mission Planned a few times with no luck, it must have been sticking in my face. I remember looking at the param's at the four major flight controls assignments which are the very next ones. DOH!

Funny, the first time I looked at the list in the wiki I found it straight up

Must be dyslexic or something :)

Thanks again for your help 

Permalink Reply by Remco Vos on January 31, 2015 at 1:30pm

I would like to share my story to get this to work. I followed everything in this thread with no success so far. Until today.This might help other people as well.

I was struggling with getting EzUHF RSSI to work on MinimOSD-extra. Today I got another OSD unit, with the same result. That made sure it was not in the OSD I had already.

Then I went on searching. One more time through all settings. At the end I decided to take a good look at the SR2 settings. There's also a channel setting. I changed the value here from 0 to 8 and, voila, working! I changed it back, not working again. So, it was all in the SR2 settings. My Minim is connected through SR2. Since everything else was working here I never expected to look in that setting. I had to change some other stuff there to get it working in first place. This was before I started working with RSSI. Never thought there was a channel setting in there. Anyways, it works now.

The settings which work for me:

Mission Planner
CH8_OPT 0
RSSI_PIN -1
RSSI_RANGE 3.3 (no matter, will not used anyways)
RC8_DZ 0
RC8_FUNCTION 0
RC8_MAX 1793
RC8_MIN 1056
RC8_REV 1
RC8_TRIM 1056
SR2_EXT_STAT 2
SR2_EXTRA1 5
SR2_EXTRA2 2
SR2_EXTRA3 0
SR2_PARAMS 0
SR2_POSITION 0
SR2_RAW_CTRL 0
SR2_RAW_SENS 0
SR2_RC_CHAN 8

EzUHF
PPM 8 LINK
CH1 PPP Muxed
All others, default

MinimOSD-extra
RSSI channel Channel 8
RSSI Min 1056
RSSI Max 1793
RSSI Warning 60%
Of course in the panels also RSSI enabled

Permalink Reply by Ross McGowan on January 31, 2015 at 6:51pm

RV

I know this is a thread relevant to Pixhawk, are your findings for a Pixhawk or APM setup?

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