702 Brushless Whoop

By Davidpe on Jan 15, 2023

5  230  2

Ya, it's another brushless whoop with a Diamond F4 board! It's been awhile and thought I would try the 702 motors that everyone's been talking about for the last year. I normally fly 802's however most of my builds are a little chunky as they have random left-over parts from other builds. I tried to keep this one light to see if I could feel the difference. Sure enough, I love the 702's and the lighter AUW is a huge bonus for indoor freestyle. I don't think I'll be going back to 802's as I haven't flown them since I built this new one.

This build is super simple however I did come across a pretty good challenge with the internal SPI ELRS rx. Almost all of my recent micro bulids include the ELRS EP2 external rx. I love the ceramic antennas as I'm mostly flying toothpicks in small areas and they are super simple to set up and do the job. I would say I'm well versed in using the ELRS system so my challenge binding the Diamond F4 board was something I wanted to capture with a few resource links just in case someone else might benefit.

Betaflight 4.4.0 will have full ELRS integration that should make it easy to use ELRS v3.0 with both your SPI and serial ELRS receivers. With an integreted ELRS SPI reciever it is neccessary to update the Betaflight hex to update the ELRS version. You are not able to independently update the rx using the bind phrase, wifi, or passthrough method. (like you're able to do with a serial ELRS on a dedicated UART). At the moment(January 14th 2023), in order to bind, you have to downgrade your ELRS TX to ELRS v2.0 and use the firmware that comes on the Diamond F4 or use a special Betaflight 4.3.1 test hex that's been created that enables you to use ELRS v3.0 with both your integrated SPI rx's and your serial rx's. Hope that makes sense.

So here are a few links that will make it easy to update the Happymodel Diamond F4 ELRS SPI flight controller. Simply download and flash the Betalfight test target CRAZYBEEF4SX1280 4.3.1 here: https://www.happymodel.cn/index.php/2022/09/26/crazybeef4sx1280-4-4-0-support-expresslrs-v3-0-beta-version-firmware-download/?fbclid=IwAR2aOhyQG4KlJnVysq-6FWcfsOcP1ljamrK50A15RjQ0Sr0wusM7YZ0a7EU . There's also a recent video that was produced by Toronto FPV to help this process:

Ensure that your ELRS TX is on the latest v3.0 release using the ELRS Configurator. You can then follow the ELRS SPI page steps to bind here: https://www.expresslrs.org/2.0/hardware/spi-receivers/ I personally use the binding phrase method at the bottom of the page. You simply type your unique ELRS TX binding phrase and it spits out a list of 6 numbers (UID Bytes) that you then copy and past into the CLI of your FC. It's a slick little macro and once the CLI is saved and the board is rebooted, you will see that sweet solid red LED that indicate a succussful bind!

Hopefully that helps a few of you. And it will definately help me when I forget what I did to bind!



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baggszilla   Feb 04, 2023  

Very nice race build!

Davidpe   Feb 04, 2023 

Thank you! Pretty easy build and it flies great

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