Thread Tools
Nov 04, 2016, 06:08 PM
Registered User
Sebastos's Avatar
It's great ! Good job flipflap !
Sign up now
to remove ads between posts
Nov 04, 2016, 06:31 PM
RC fanatic

ULRS repeater configuration


Just realised that I had never posted any images of my FrSky->ULRS repeater before I tore it down to use the components for my direct Taranis module.

The reason I originally built the repeater as opposed to having ULRS directly connected to the Taranis, was that I wanted my Teensy S.Port telemetry solution to be a part of my ULRS configuration, and at the time this was before the smart port telemetry library contained the polling code (which my current directly connected ULRS solution uses - see this post for details: https://www.rcgroups.com/forums/showpost.php?p=35971640 )

So using a repeater has some distinct advantages over a directly connected ULRS Tx, such as:
  • can be placed high up on a pole to get better antenna elevation
  • allow the ULRS Tx to be moved away from your Video Rx
One disadvantage though is that it allows only 8 channels (limited by FrSky CPPM output from X4R).

Some pics of solution below (housed in an IKEA plastic sandwich box)
Nov 04, 2016, 09:58 PM
Registered User
Quote:
Originally Posted by flipflap
Aah.

So that was it !

A few days ago a user asked a question regarding the imprecision of the arduino at 115200 bauds, which is of several percent, much more than for other baudrates.

You remember I had a series of FTDI cables which didn't work correctly, and other cables that worked correctly ?

Well it's very simple, when using the arduino code set for 115200 bauds, it actually sends something like 117647 bauds.

Some FTDI adapters can handle it, some can't, it's really at their limit.

So for ULRS CC, I tried with different baudrates, using my 'bad' FTDI cables, and for all baudrates between +-117000 and +-12000 it works perfectly !

I guess this can explain a lot of issues we've encoutered, for example

-switching from TX to RX (because it happens at 115200 bauds, the reverse operation happens at 19200 which is fine)
-saving parameters
-glitches / flickering of the ULRS CC display, or no display at all
-users who were able to flash their OrangeRX, but not to use ULRS CC (because the flashing occurs at 57600 bauds)

I'll push a version with this modification tomorrow.
Well, we improved a lot today, thanks to gregd72002, he pointed to a fly and Ben finally killed "the" bug!
Nov 04, 2016, 11:06 PM
Registered User
gyrex's Avatar
Quote:
Originally Posted by athertop
Just realised that I had never posted any images of my FrSky->ULRS repeater before I tore it down to use the components for my direct Taranis module.

The reason I originally built the repeater as opposed to having ULRS directly connected to the Taranis, was that I wanted my Teensy S.Port telemetry solution to be a part of my ULRS configuration, and at the time this was before the smart port telemetry library contained the polling code (which my current directly connected ULRS solution uses - see this post for details: https://www.rcgroups.com/forums/showpost.php?p=35971640 )

So using a repeater has some distinct advantages over a directly connected ULRS Tx, such as:
  • can be placed high up on a pole to get better antenna elevation
  • allow the ULRS Tx to be moved away from your Video Rx
One disadvantage though is that it allows only 8 channels (limited by FrSky CPPM output from X4R).

Some pics of solution below (housed in an IKEA plastic sandwich box)
Thanks for this athertop! This is similar to the setup I'll be building Your advantages are the same reason I'm planning on using the repeater setup. Thanks for sharing!
Nov 05, 2016, 12:59 AM
Registered User
Dancy's Avatar
Holy cow......$4.....f o u r .....bucks?

http://www.zdnet.com/article/move-ov...inux-computer/
Nov 05, 2016, 01:33 AM
Registered User
Thread OP
It's especially impressive because of its size, but add one buck and you get a raspberry zero which is faster, and has more memory, ftdi output etc.

At that price tag, and with its included wifi connectivity there's no reason not to include it in a car, fridge, oven or electric heater, it's a good candidate for 'internet of things' applications.
Nov 05, 2016, 01:39 AM
Registered User
Thread OP
Intel's 500 Drone Light Show | Intel (2 min 32 sec)


OK, so what's the next step ?
Nov 05, 2016, 02:34 AM
Registered User
Thread OP

ULRS 2.32.e released


The main change in this version is the baudrate adaptation, let me know how it works for you.

Remark : this should make all FTDI adapters work with ULRS, even cheap ebay clones.

However there's a specific case that still requires a good FTDI adapter : the Wolfbox modules are different from the other modules because they require a 115200 bauds speed for flashing. But avrdude doesn't seem to accept unusual baud rates such as 117000 which would be required. So for Wolfbox modules flashing (and only for flashing, not for normal use), a good FTDI adapter is required.
Nov 05, 2016, 02:41 AM
Registered User
Thread OP
A user has provided a how-to video to flash Wolfbox modules with ULRS here :

wolfBox (2 min 5 sec)
Nov 05, 2016, 03:39 AM
Registered User
Nothing to see here move along all
Last edited by yak-54; Feb 22, 2018 at 04:50 AM.
Nov 05, 2016, 07:11 AM
Registered User
Thread OP
To answer a recent question from Narpat regarding the spectrum analyzer precision in ULRS CC, I did a simple test using a DI-O remote control of known frequency (433.920MHz), and attached is a screenshot of the ULRS CC spectrum analyzer result.

We can see a peak at 433.950MHz, which is relatively precise (0.007% error).

The error is due to the fact that the spectrum analyzer as it is implemented does only measure the power on the actual channels used by ULRS, which are spaced by 150 kHz. So it will always provide the closest frequency multiple of 150 kHz, starting at 432MHz.

In this case 433.950MHz = 432.000MHz + 13 * 150kHz is the closest channel to 433.920MHz.

The low background noise level is due to the fact that a dummy load was connected on the ULRS module during the test.
Nov 05, 2016, 07:13 AM
Registered User
Quote:
Originally Posted by flipflap
The main change in this version is the baudrate adaptation, let me know how it works for you.

Remark : this should make all FTDI adapters work with ULRS, even cheap ebay clones.

However there's a specific case that still requires a good FTDI adapter : the Wolfbox modules are different from the other modules because they require a 115200 bauds speed for flashing. But avrdude doesn't seem to accept unusual baud rates such as 117000 which would be required. So for Wolfbox modules flashing (and only for flashing, not for normal use), a good FTDI adapter is required.
Do you think this would have solved the problem I was having?
In my case only the cheap eBay FTDI adapter worked, while the expensive one I bought through 3DR did not.
Nov 05, 2016, 07:38 AM
Registered User
Thread OP
I can't give a list of which ones will work or not, but it's possible that even expensive ones don't work.
The cheap adapters I had from ebay had a real FTDI chip inside, but didn't work for example.

I wonder if this could be one of the reasons why Arduino stopped using FTDI chips on the Arduino boards, to replace them by an atmel microcontroller doing the same job.
Nov 05, 2016, 08:02 AM
Registered User
Nothing to see here move along all
Last edited by yak-54; Feb 22, 2018 at 04:50 AM.
Nov 05, 2016, 09:40 AM
Registered User
Thread OP
I don't know, but I also see a small 450 MHz peak. Maybe an interference from the RFM's 30 MHz clock.


Quick Reply
Message:

Thread Tools