Re-programming a Receiver as a Transmitter Happymodel EP2

[ewcook]

Unable to get EP2 with TX firmware to bind with Radiomaster RX PWM.

https://headtracker.gitbook.io/head-tracker/getting-started/wiring/elrs-setup

I tried both 3.1.2 and 3.0.0 on the Radiomaster receiver without any luck. I have also verified the binding phrase.

Please let me know if there is another firmware available for the EP2 to run as a TX, or if there is a procedure I can follow to build my own.

Thanks,
Ed

[dlktdr]

When binding, did you double check the RX and TX wiring to the Head Tracker and making sure the UART mode is set to CRSF output? If it's not receiving CRSF data then it just looks like it's not bound.

You do need to be using version 2.2 firmware and 2.2 GUI to get CRSF feature. Links how to download the development version here. https://headtracker.gitbook.io/head-tracker/support/development/git-workflow-and-actions

You can pretty easily compile your own downloading the ELRS source code, opening it with VScode and Platform IO and choosing the DIY_2400_TW_DUPLETX_via_xxx then Build. EDIT: You would set your HEAD to the TAG of the version you want to compile in GIT first.

Remembering to choose the binding phrase under user_defines.txt

[ewcook]

I have not wired it up to the head tracker yet. Wanted to verify I could bind with the receiver first. I will go back to the bench and wire it to the head tracker and make the necessary changes for CRFS and try it again.
Thank you!
Ed

[ewcook]

Wired rx-tx and tx-rx on the board. Updated the firmware and select CRFS output, but it still does not bind.

[dlktdr]

Just had a thought about this on the ELRS setup page of the tx, do you have uart invert selected in the settings?

[ewcook]

I confirmed I have UART inverted selected in the settings.

[dlktdr]

I just confirmed what I have on mine, I have UART inverted checked as well.

There are not many users that I know of doing this so I would like to help track down your issue and to help future users.

Just released a 2.2-pre-release with firmware included. If you can flash this firmware with this GUI to be sure we are on the same page.
https://drive.google.com/file/d/1DVPoDp4ZXhoI9SxvCinXkAfCYj1iWv1L/view?usp=share_link

Could you post photos of the wiring. Most of my tests have been with the DTQ Head Tracker board, mainly because it has 5v easily available. Are you using this with a Nano 33 BLE?

What RM PWM receiver do you buy. I can order up one of them for testing. I'm looking forward to checking them out anyway. Been using CRSF to PWM boards currently... less soldering with a direct to PWM 😄

[ewcook]

Here is my wiring

I have a HappyModel EP2 receiver and Radiometer ER5C PWM Receiver.

Thank you for all the help!

[andrzejroszkowski]

There is new feature in v3.3 called AirPort, maybe it is worth to check if it will work in RX2RX scenario... I've asked a question in this PR: ExpressLRS/ExpressLRS#1904

And one more - ExpressLRS/ExpressLRS#2060 - Wireless Head Tracker...

[ewcook]

Decided to continue using my TX16S for a communication link