ESC reboots when running motor tests (using DShot150)

Hello. I have a quad with a Kakute F7 flight controller running Copter 4.0.3 and an iFlight SucceX 4in1 2-6S 50A ESC. I have 4 iFlight XING X2208 1700KV motors.

When I run the motor tests in Mission Planner, the motors run for a while and then the ESC’s start rebooting (I hear two beeps and one or more of the motors move slightly back and forth). The rebooting usually happen right after the motors stop, but sometimes also during the motor test or a few seconds after the test completes.

MOT_PWM_TYPE is set to DShot150. I found out that the rebooting does not happen if I set MOT_PWM_TYPE to 0 (PWM). So the problem seems to be related to the DShot protocol?

I have also tested installing Betaflight on the Kakute F7 and set it up with DShot150. When I run the motor tests in Betaflight Configurator I am unable to reproduce the issue. So the problem seems to be related to ArduCopter. (Also, when I run motor tests in BLHeliSuite32 the ESCs do not reboot)

I was first suspecting that there could be something wrong with the hardware, so I have actually tried both to replace the Kakute F7 flight controller with a new one and I also tried to use another ESC (Tekko32 BLHeli32 4-in-1). But even when replacing the hardware I saw exactly the same problem.

Does anyone have a clue why this happens and how I may proceed to debug or solve the issue?

There was a bug fixed recently on master related to DMA conflicts on these boards. What do you have attached to SERIAL1? Can you try turning off DMA on that port to see if it helps (SERIAL1_OPTIONS)

I have the SmartAudio cable from my VTX attached to serial 1 TX (and nothing on serial 1 RX). But I have disconnected the VTX and the problem still persists. I can try to solder off the cable and see if it has any effect.

Do I need a fresh build from master to turn off the DMA on the port?

I don’t think you need a fresh build, but if you are building master - then try that as it has the fix.

FYI. I tried to install the latest daily build of Copter, and so far the problem has not occured.