ELRS connection issues

[pearl glacier]

I have a Skystars F722 Mini HD Pro 2 FC and a happymodel EP dual 2.4ghz elrs rx. I also use DJI video but it's currently disconnected from my FC because I've seen online that it can cause issues.

I can confirm the following:

• flashed latest version of betaflight (4.5.2) with CRSF selected
• radio -> rx connection works, getting valid telemetry data back and can see the RX in the lua script
• Updated both TX and RX to latest version of ELRS, 3.6.0
• EdgeTX is v2.7.1
• crossed rx, tx uart wires, confirmed connection with multimeter
• selected uart1 for serial RX

Used the following wiring diagrams:

https://www.firstquadcopter.com/wp-content/uploads/2022/12/SKYSTARS_F722HD_Pro_wiring_diagram.jpg
https://www.happymodel.cn/wp-content/uploads/2022/11/未标题-1-拷贝31-1000x500.jpg

CLI diff:

# 

# DIFF all

# version
# Betaflight / STM32F7X2 (S7X2) 4.5.2 Mar 31 2025 / 22:18:34 (024f8e13d) MSP API: 1.46
# config rev: b606002

# start the command batch
batch start

# reset configuration to default settings
defaults nosave

board_name SKYSTARSF7HDPRO
manufacturer_id SKST
mcu_id 0024001e3232501120363848
signature 

# resources
resource MOTOR 1 C09
resource MOTOR 2 B07
resource MOTOR 3 C08
resource MOTOR 4 B06

# feature
feature GPS
feature TELEMETRY
feature LED_STRIP
feature OSD
feature ESC_SENSOR

# serial
serial 0 64 115200 57600 0 115200
serial 2 1024 115200 57600 0 115200
serial 3 2 115200 57600 0 115200
serial 5 1 115200 57600 0 115200

# beacon
beacon RX_LOST

# master
set dyn_notch_count = 1
set dyn_notch_q = 500
set acc_calibration = 15,8,157,1
set serialrx_inverted = ON
set serialrx_halfduplex = ON
set dshot_bidir = ON
set align_board_yaw = 180
set yaw_motors_reversed = ON
set small_angle = 180

profile 0

profile 1

profile 2

profile 3

# restore original profile selection
profile 0

rateprofile 0

rateprofile 1

rateprofile 2

rateprofile 3

# restore original rateprofile selection
rateprofile 0

[pearl glacier]

https://pyrodrone.com/products/copy-of-happymodel-2-4g-expresslrs-ep1-dual-tcxo-rx-true-diversity-receiver-module?variant=40573669179435

I'm not sure on exactly where to find the min HD pro 2, can't see anything about it online and the page was removed from pyrodrone. Anyone know what that means?

[leaden snow]

I would try uart 2 or 5, some fc have this problem

[pearl glacier]

this appears to have fixed it. However, I did a test flight and my quad fell out of the air randomly. I was not able to rearm without power cycling and there was a solid red led on the flight controlller. I felt the frame and the flight controller cpu was extremely hot, way too hot to leave my finger on for more than a second. I also noticed that my cpu load% in bf configurator is hovering around 70-75%, which seems high. I'm wondering, do you think I have a busted FC?? I feel like an F722 cpu should be more than capable of handling the PID loop, but it seems to take about 50% of the cycles even just sitting on the bench, is that normal?? It got up to 107 degrees C just sitting on the bench while plugged in. Without the battery it idles at around 93c, which still seems insanely high from just USB power.

[cosmic cipher]

PID loop for the F722 should be 4 kHz with DSHOT300.
But I have a feeling that the temperature won't magically be fine with those settings. 100+ is absurd.

No shorts anywhere?

[leaden snow]

try as @cosmic cipher says, then check tasks and status in cli to see what is causing such an high cpu load

[pearl glacier]

Even just connecting to usb power quickly raises the cpu temp to >75c, which is quite dangerous. I've set my pid loop to 4k, and dshot300. My cpu usage is now closer to 30% with nothing connected, pid loop is taking almost all of that 30%. I tried visually inspecting the board but don't see any issues. I assume this has something to do with my 10v regulator randomly dying. If y'all have any ideas on how to prevent the cpu from overheating, I would really appreciate you saving my board!!

In the meantime I replaced it with a different FC and things seem to work well, but I would like to be able to have this one as an emergency backup instead of just tossing it

[leaden snow]

i would contact skystars, see what they say

[ember hinge]

could you send me the link for betaflaght 4.4.2

[cosmic cipher]

@ember hinge What does your question have to do with this thread?