TCMMRC Rebuild - Happymodel EP2 ExpressLRS 3.0 - Receiver Install 

I'm glad I was able to help!! It's also my way of learning as well, to plan and explain what the steps are, so we're all learning together😁👍 I'm always worried my videos are too long, but I intend to keep the small details in because those are the things that help me in other people's videos. Also, although ELRS is a pain to set up and initially understand, it's a great protocol and hopefully get improved initial set up for first timers as the tech matures.

If you have the EP2 all set up using TX and RX (a full UART), then there's no need for subs and they can be unsoldered.

You are absolutely right that the arming should be set to AUX1 for ExpressLRS. However, I didn't set any modes in this video or the arming channel. Perhaps what was there is the defaults, but I couldn't see after reviewing the video. Check out my other video in this series called "TCMMRC Rebuild - Betaflight Config + First Flight" where I set up the modes and arming is set on AUX1. Apologies if I have done something that may have been confusing..

I don't think that would work, sorry. The rp2 operating voltage is 5v, so even though it will work when the 1s battery is fully charged at 4.2v, by the end of the pack at around 3.5v, the voltage will be too low and cause the receiver to behave unpredictably or brown out. It could very well work and be fine most of the time, even at 3.5v, but it's not within spec of the rp2 so you'll risk losing connection. You'll need to power it from a 5v regulated pad (step up) on the 1s flight controller.

Hi. This is a known issue with some modules and it has to do with the way the "partitions" are managed on board. Check out Joshua Bardwell's video "ExpressLRS 3.0 "Bad Size Given" "Not Enough Space" error (HOW TO FIX)". I've not run into this issue myself yet, so I can't give you my experience with resolving it. Sorry!

Do you mean just for power? The 5v and ground?

@@nxp200 yes. Power would be double used. Tx and rx are free anyway

@@kaskalo2 it depends on the 5v regulator the receiver is running off. What flight controller?

@@nxp200 it is diamond F4 5in1 AIO

@@kaskalo2 I've checked the flight controller specs and it has a 5V 1A BEC. This means if the current draw from components such as receiver, VTX, camera, etc increases above 1A, it may start to overheat and possibly cause damage. The Runcam Thumb draws 280ma@5V (from Runcam website). Personally, if I would really want to do this, I would measure the 5V equivalent current draw of the diamond without arming. If the sum of that with the 280mA of the Thumb is 1A or more, I would not try it on the diamond. That's just me though, others may have a better opinion or solution to this.

Hmm. Not sure, but I would check the in the Receiver Tab, receiver mode is set to serial and the serial receiver provider is set to CRSF. Do you have another available UART to try? Perhaps swapping to a different one might work.

@@nxp200 yes it is set to CRSF. I did not try with a different UART from the fc yet. But I found out that if I set the receiver on uart 3, then the log shows passthrough using uart 2. Somehow I see that it is reading my config. But in both event, it still doesn’t work for me. I tried using an external uart and setting to uart and it failed too. I just ordered another receiver… I can’t think of anything else to try.

You could try to connect to the receiver via WIFI to flash it. There are other videos out there that show how to do this, but the general steps are: 1) build an ExpressLRS file with the correct target 2) power the receiver and wait 60 seconds. A wifi network named ExpressLRS RX will be broadcasted 3) using your computer, connect with the password "expresslrs" 4) open a browser and navigate to 10.0.0.1/ 5) open the Firmware Update page and select the build file created in step 1 6) click Update and the flashing will begin. Note: Do not power down the receiver during fishing!! More detailed steps here: www.expresslrs.org/software/updating/wifi-updating/ Hope this helps!

@@nxp200 thank you very much but I had done exactly that but with the wrong file. Yes I screwed up. And since then, I have a solid led on. That is why I was trying the passthrough method.

Solved… I was able to upload the 3.3 firmware using a USB- UART device. Then from that point on, the passthrough and the wifi updates could work fine. Thanks.

I've used Intel and M1 based MacBook Airs but haven't had any issues connecting to the FC. I would suggest trying other USB cables that you may have since some are not capable of transferring data. Otherwise, does the FC boot up when plugging in a battery?

In US dollars, TCMMRC UR26 Mermaid quad $89 SkyStars KO55A ESC $45 Happymodel EP2 Receiver $15 Total $149 The 55A ESC isn't absolutely necessary, but that was something I wanted to upgrade personally. The 40A ESC that came with the quad should be ok. I'll be using it in another build or as a backup anyway.

Here's a video I did a while ago. Hope it helps. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-gXglXUEFV-Y.html

Firstly, Congrats on the Boxer! Apparently hard to get and also a very good radio! On my "to-buy" list. In terms of ExpressLRS, you'll need to flash the Boxer and Flywoo Firefly with the same "major" version using the software called "ExpressLRS Configurator". Eg, ExpressLRS version 2.x on both radio and quad, or 3.x on both. Can't have 2.x mix with 3.x. The software is used to flash both the controller and receiver on the quad. I'm not sure if the Firefly 1s has an SPI or UART based ExpressLRS receiver, but it would be best to flash with ExpressLRS firmware version 2.x (latest available) just to be sure (2.x works with SPI or UART based). I also am not sure of the "Target" for either controller or quad, so try messaging the ExpressLRS Discord group to find out. The "Target" tells the configurator software what type of hardware it needs to flash/update, so needs to be correct. Steps I would take: 1) find out Target for both Boxer and Quad in ExpressLRS Discord server 2) flash Boxer with ExpressLRS 2.x to the target found in step 1 and set bind phrase 3) flash quad with ExpressLRS 2.x to the target found in step 1 and the same bind phrase as in step 2 Hope that helps. Good luck!

Thank you 🙏

Sorry about that. It's probably my crappy video editing. I'll try to normalise it better

@@nxp200 no worries, I was just really struggling to hear, thought it was my volume but it was on full, lol