PPM Blues

[Hawk404]

This is another "I can't get my Jeti receiver to talk to my Skookum 720".

But I'm not seeing the solutions in similar threads work so can someone tell me what I'm missing?

Done so far:
R3/RSW set to PPM Positive in device explorer.
Skookum set up software set to "Futaba / Jeti PPM".
Attempts made at both the default 17 ms and 20 ms.
Receiver to FBL cable tried in all 4 ports. Because I can't find which port PPM output is on in any documentation.
Different R3/RSW attempted (to eliminate bad reciever.)
SK720 has lousy documentation on imputs so signal line reversed and cable re-cycled through all 4 parts of both the first and second receiver.
Dusted off the 72mhz futaba, set SK720 to "traditional receiver" and got stick throws reflected (to take defective 720 off the table).

So that's two different R3s each with all 4 ports tried twice - once with mystery polarity on 720 one way, once again reversed.

Chasing down undocumented "PPM out" ports seemed to be the common factor in most reported failure to communicate so I'm looking for something else.

Any ideas?

[Thunder Fighter]

Which firmware are you using on the R3? If you have updated to the latest version then here are the pin outs (from the Esprit site).

Port Configurations (Rx Firmware 3.20):
Standard: 1-3 Servo, 4/Ext Telemetry/USB Programming
PPM/Servo: 1-2 Servo, 3 PPM, 4/Ext Telemetry/USB Programming
EX Bus/Servo: 1-3 Servo, 4/Ext EX Bus/USB Programming
UDI/Servo: 1-2 Servo, 3 UDI, 4/Ext Telemetry/USB Programming

So in PPM mode it is port 3.

I am using an RSat2 with PPM into my SK720, this is on 3.11 firmware but there is only 1 PPM port for use so I didn't have any problem with getting it working. I think I have set 20ms for that setup from memory.

//Dennis.

[Thunder Fighter]

I have updated the above post as I must have copied the wrong info the first time.

//Dennis.

[Hawk404]

Thanks but there is no discernible difference regardless of which port is used - they all don't work equally - port three got tried twice with two separate R3s (as did all the other ports).

Right now I've got the Skookum working in "traditional" mode using an R7 I had on hand. Which oddly enough provided me an opportunity to get more practice with the servo connector crimping tool which provided me with an ugly but working version of the Skookum cable.

It does however look like a nest of snakes and I'll probably revert to Spektrum sats - I like the Jeti but right now I'm glad I kept the DX-18.

If I can't get the PPM thing sorted out the Jeti will have very limited applicability.

[osat]

Hi.
Setup like this:

1.Model/ Device Explorer/ R3 ( or the name of used Rx) EX:
Output mode PPM Positive (in some rare cases Negative)
Output period 20ms
No. of channels 8 channels
Fail-Safe Disabled/ Enabled (try both options)

2.System/ Configuration:
Transmit frequency 100Hz

If still don`t work try to Load latest Rx Update 3.21.

Best regards.

[Hawk404]

Originally Posted by osat

Hi.
Setup like this:

1.Model/ Device Explorer/ R3 ( or the name of used Rx) EX:
Output mode PPM Positive (in some rare cases Negative)
Output period 20ms
No. of channels 8 channels
Fail-Safe Disabled/ Enabled (try both options)

2.System/ Configuration:
Transmit frequency 100Hz

If still don`t work try to Load latest Rx Update 3.21.

Best regards.

Thanks! How do I do that?

Or, more to the point, where can I get the little blue gizmo shown here:

http://www.jetimodel.com/en/Download...rs-Tx-Modules/

[gelatmi1]

Near you:

http://www.espritmodel.com/jeti-tele...b-adapter.aspx

FW for R3 is 3.20 (3.21 is for RSAT2 only)

[Hawk404]

Ah. Hiding in plain sight it would seem.

Here's hoping...

[Rockarruda]

The skookum side uses IO-B as the ppm port also.. I didn't see if you mentioned that..

[Hawk404]

Yup - IO-B on the SK and port 3 on the Jeti - should cut down on the fire drill where I try every port to see if they got moved.

IO-B also serves as "Elevator In" when using a "traditional" receiver, which worked fine.

Since it works fine with ports as per the manual when set for "traditional" I've pretty much ruled out mis-labeled ports on both the SK and Jeti.

With an R7 set to "servo output" everything is fine. The only glitch is with PPM on an R3 - either one of the two I have so I'm also ruling out a defective R3 - anything's possible but it doesn't seem likely I'd get two PPM dead R3s at once.

The 100Hz transmitter frequency was the factory default so no need to change that.

There isn't a "PPM specific" cable is there? I tried both a 3 conductor standard and one that had a signal lead only - no + or - pins.

[zortness]

After you switch the R3 to PPM mode or change any of the pulse lengths, you need to cycle the power.

You probably want PPM+, 22us.

[Thunder Fighter]

As another test you can try using the R7 to PPM mode as that will confirm if it is a faulty R3.

//Dennis.

[Hawk404]

The Skookum does a hard reset when the receiver type is changed in the software and I was doing a dance with the output cable and battery cable on the R3s. The battery can't go into port 4 so I was moving it around while hunting mystery PPM-out ports with the connector cable - those two had enough power cycles to please a fleet of cable modem tech support gurus.

If the R7 worked in PPM mode it wouldn't indicate a bad R3 - it would indicate two bad R3s as I'd already gone through the port hunts with the two I had. Still, it's probably worth a shot. Any idea what the PPM-out port on the R7 might be? And would it change after the little blue gizmo shows up for the firmware updates?

As odd as it sounds it's shaping up to be a partially defective SK720. Just because it works with a receiver (any receiver) in "traditional" mode wouldn't necessarily mean the PPM-in portion isn't broken, or would it? For what it's worth the setup software for the SK freezes every few minutes much like the software did on an MSH Brain which turned out to be defective.

One thing I like about this hobby (OK, not really, I'm trying to see a silver lining here) is that some of the diagnosis turn up some pretty strange stuff. In searching for similar issues at least one guy solved it by replacing a defective receiver-to-FBL connector - that strikes me as pretty low odds and something one wouldn't try for at first.

Kinda like discovering a computer print issue was related to a defective LPT-1 cable. This happened to me once but it probably gives away my pre-USB age.

Or discovering that a gyro-servo combo pack would show up with a dead tail servo that I only figured out after spending a day blaming the gyro setup. And it wasn't incorrect settings for the gyro - the thing was dead as a doornail.

Realistically, the next most logical step is to try either of the R3s with another FBL unit. I'm just not eager to go through the setup again on any of the ones I have working. But I'm betting it's more likely the FBL than the firmware. This assumes that if the receiver firmware was horrendously out of date this would have showed up in "device explorer".(?)