# VOXL ESC Mini

Source: https://forum.modalai.com/topic/3222/voxl-esc-mini
Category: ESCs, Sensors and Accessories (https://forum.modalai.com/category/15/escs-sensors-and-accessories)
Tags: esc
Posted: 2024-03-15 17:05:07 UTC by 0x45
Replies: 5 · Views: 941

## 0x45 · 2024-03-15 17:05:07 UTC

Hi,

Model: VOXL ESC Mini 4-in-1 with Built-in Power Module
Firmware: modalai_esc_firmware_m0129_3_v0_39_RC10_eb6fb500.bin

I'm not using all of the ESC outputs and I'd have set them to disable. 
Although, the current firmware on the PX4 does not support the disable feature. I was wondering if there was a particular reason that this capability does not exist? 

![Screenshot 2024-03-15 093307.png](https://forum.modalai.com/assets/uploads/files/1710521040945-screenshot-2024-03-15-093307.png)

## Reply by Alex Kushleyev (ModalAI staff) · 2024-03-15 17:32:53 UTC

@0x45 , there is no particular reason. I think we just assumed that all 4 motors would be used. Is this something that is needed for your application? it is not a limitation of the ESC firmware itself, instead the PX4 driver for it.

## Reply by 0x45 · 2024-03-15 19:04:19 UTC

For my application it would be preferred. I saw where it is in the PX4 driver - I just was hesitant to make the changes and wanted confirmation from the ModalAi team that there isn't any issues on the ESC side if I were to make the change. 

Thanks for the speedy reply and I'll proceed on if there is no issues.

## Reply by Alex Kushleyev (ModalAI staff) · 2024-03-15 20:30:52 UTC (in reply to 0x45)

@0x45 I believe that if you allow DISABLED to be the setting for the channels 1-4, then the mixer will output 0 for those channels (based on this : https://github.com/modalai/px4-firmware/blob/voxl-dev/src/drivers/actuators/voxl_esc/voxl_esc.cpp#L56)

My guess is that when you arm, the disabled channels will just stay at zero, causing the voxl esc driver to just send 0 rpm target for that ESC channel.

The worst that could happen is that mixer could send MAX_RPM to the disabled channel (but i don't see how that would happen).

If you want to try it out, i suggest making the change to allow the DISABLED actuators and then in `updateOutputs` just print the values and force them to zero before sending out to ESC in order to avoid any unexpected rpm values to be sent out : https://github.com/modalai/px4-firmware/blob/voxl-dev/src/drivers/actuators/voxl_esc/voxl_esc.cpp#L1162

I think you can just comment out this lines:
https://github.com/modalai/px4-firmware/blob/voxl-dev/src/drivers/actuators/voxl_esc/voxl_esc.cpp#L318 and
https://github.com/modalai/px4-firmware/blob/voxl-dev/src/drivers/actuators/voxl_esc/voxl_esc.cpp#L336 (`ret = PX4_ERROR;`) -- this will disable the errors

If you want to wait a few days, i can try it out sometime next week..

## Reply by 0x45 · 2024-03-15 21:09:07 UTC (in reply to Alex Kushleyev)

@Alex-Kushleyev 
Sounds good I'll give it a shot. Thanks!

## Reply by Alex Kushleyev (ModalAI staff) · 2024-03-15 21:18:58 UTC (in reply to 0x45)

@0x45 if you get it working and you would like to share your change, we can test and incorporate into the driver. That could potentially make it easier for you to not have to use a custom px4 build for your application.