Help! TBS Crossfire Micro v2 rx - M8N GPS - Omnibus F4 v2 fc connections

[mountaindewdude76]

Hi guys....I have a UART dilemma. I'm wanting to install a spare Omnibus F4 V2 into my S800 wing with Inav. I've done this install once before on my 49" fpv wing but the difference is that I have a TBS Micro v2 rx in my S800 wing and the install is a bit different for me. I've been asking around and I've been getting a lot of negative comments because I'm asking questions that seem to be "easy" for many people but I'm still uncertain. In my 49" wing, I have the Omnibus F4 V2 and M8N GPS installed and I'm using a Spektrum AR7700 rx, so I have the AR7700 rx connected to the PPM/SBUS pins on the PWM rail, then I have the GPS unit connected to UART6, as per Matt's (RagTheNutsOff on Youtube)video tutorial on installing Inav on an Omnibus F4 v2 using the M8N GPS unit. Everything works real well on the 49" wing.

But, I'm being told that I need to connect the Micro v2 rx to a spare UART (many people are saying UART6) and move the GPS to a different UART. I've had some time to think about it and I'm wondering if I can do something. Can I still connect the GPS unit to UART6, using the 5v, ground, rx6, and tx6, and then connect the Micro v2 rx to UART3, using rx3, tx3, and the same 5v and ground as the GPS unit? I have attached an illustration that shows my thought.

Or would you guys have a better suggestion?

 

[ElectriSean]

That should work fine. You can also get your 5V and ground from elsewhere on the FC if you don't want to splice wires. I think this makes a cleaner build. The only issue I see is that UART3 seems to share pins with the I2C bus, so if you want to use a magnetometer or OLED display you'll have to pick a different UART.

 

[mountaindewdude76]

The magnetometer isnt a concern, so we're good there. What is the OLED display?

 

[ElectriSean]

It's a small display you can add to give you basic status information. Handy, but not necessary.

 

[mountaindewdude76]

Ok, so thats a seperate display on the model.

No, i wont be using an OLED (never heard of it til now.

I'll run the Micro v2 to the rx3 and tx3 and get the 5v and ground from elsewhere on the fc. Then run the gps unit to the rx6, tx6, 5v, and ground.

Thanks for the help. Now lets just hope that the UARTs cooperate and let me do it lol

 

[mountaindewdude76]

What is an inverted UART?

 

[ElectriSean]

What is an inverted UART?

Essentially high signals are low and low signals are high. This is used by FrSky SBUS and Smart port telemetry. Whichever UART on your board is assigned to the SBUS pad will be inverted and not suitable for you to use. In the good old days of F1 and F3 processors, inversion could be done in software (or firmware) but F4's need to do this in hardware on the board itself.

 

[mountaindewdude76]

Thanks for that.

How do i know if a UART is inverted or not?

If i connect to an inverted UART and not know, will it just "not work" or will it short out and burn up?

 

[mountaindewdude76]

What im trying to get at is this...

I want to connect my m8n GPS and Crossfire Mico v2 rx to an Omnibus F4 v2 fc and, simply put, i dont wanna mess anything up.

 

[mountaindewdude76]

No plans to use the magnetometer nor an OLED, so, im hoping to carry on with the install.

I appreciate everyone's help here. I've been flying rc's for many year using Spektrum gear. Now i have a Taranis with Crossfire and its like im learning all over again.

 

[ElectriSean]

Thanks for that.

How do i know if a UART is inverted or not?

If i connect to an inverted UART and not know, will it just "not work" or will it short out and burn up?

You'll have to check the manual, but I believe that board only has 1 inverted UART assigned to the SBUS pad. If you connect to one by mistake it will just not work, you won't short anything out.

 

[ElectriSean]

That should work fine. You can likewise get your 5V and ground from somewhere else on the FC on the off chance that you would prefer not to graft wires. I think this influences a cleaner to manufacture. The main issue I see is that UART3 appears to impart pins to the I2C transport, so on the off chance that you need to utilize a magnetometer or OLED show you'll need to pick an alternate UART.

Developing a plagiarism app? LOL