I am new to the forum and Ardupilot software in general. Below are the two issues I am currently trying to solve but have not been able:
I want to use counter-rotating propellers for Bicopter airframe class.
I want to add a boost throttle to Bicopter airframe class.
When I configure servo outputs normally as one would for Bicopter, all motors spin during motor test via Mission planner. However, assigning two pins (AUX 1,2 ) to left throttle and two pins (AUX 5,6) to right throttle results in most motors twitching or failing to arm. Same is the case when I assign one of the pins to boost throttle. I am using Pixhawk 2.4.8 (most likely clone version). The ESC I am using are 35A Cyclone BLHeli_S with Blue Jay. I suspect either Pixhawk is resource constraint or I would have to edit the firmware for custom Bicopter logic.
There is not enough information to help. A parameter file, a test flight log (even if the machine does not leave the ground), maybe a photo of the craft are needed to get some understanding of your system.
From the bits of information provided at this moment, I would rather suspect incorrect DShot configuration rather than everything else. Nothing in your configuration suggests any kind of resource problems, and nothing so far yet suggests that the configuration is too unusual.
I have not found any obvious problems with DShot-related configuration. Your screenshots show that DShot300 is indeed activated for all affected outputs. Any Bluejay-enabled ESC I am aware of should work well with DShot300.
What I am not quite sure about is what you do with BRD_SAFETY_MASK, and in general what the testing procedure exactly is. It can well be that toggling the safety switch and bits in the safety mask at will during the single run does not play well with ESC initialization.
You see, from the viewpoint of an ESC, the board with safety switches may look like it does not send any signals - and then suddenly appears and starts sending signals before the ESC understands what is happening and establishes communication over DShot.
I have a recent (non first-person) experience with people that were working with DShot-enabled ESCs but requested a mandatory MOT_SAFE_DISARM=1 (that is, no signal to come to ESCs when disarmed). For these ESCs to work reliably, we eventually had to increase MOT_SAFE_TIME from the default of 1 second to something much higher, say 3 or 5 seconds. If what I think happens with safety enabled, you may benefit from the same.
The alternative is to disable safety altogether, and possibly power off the board fully when you switch motors.
P.S.: To the best of my understanding, you are not able to test boost motors via motor test. To test out the ESCs, you need to assign a different function to them temporarily.
Sorry for the delayed response. I have midterms coming up, so I didn’t get a chance to rerun the tests. I disabled the safety features entirely and increased MOT_SAFE_TIME to 2. With that change, I’m now able to spin all the motors. I do need to power-cycle the board after switching motors, but that seems reasonable (and safe) given the configuration change. Occasionally, the motors doesn’t respond or gives a small twitch, but after repeating the motor test a few times, it eventually runs properly.
Thanks a lot! Could not have done withour your help.