Looking for Help Understanding the GPIO mapping on the QRB5165

Jeremy Frederick

I'm using the FPV ESC and noticed the feature for switching VTX power on/off. I see in the documentation that the pin is labeled as CH0 PF0, and am struggling to figure out which pin in sys/class/gpio this refers too. Some clarity on this would be very helpful.

Alex Kushleyev

@Jeremy-Frederick ,

If you are interested in information about GPIO / PWM functionality on ESC specifically, this information should help : https://docs.modalai.com/voxl-fpv-esc-datasheet/ . The control of GPIO / PWM works by sending a special message to the ESC using UART and we have some support for this in PX4 as well as our tests scripts.

If you wanted to control GPIO that is physically connected to the VOXL2 chip, then you should look at the following documentation: https://docs.modalai.com/voxl2-linux-user-guide/#gpios and we also have a tool voxl-gpio which is part of the SDK, also source here : https://gitlab.com/voxl-public/voxl-sdk/core-libs/libqrb5165-io/-/blob/master/apps/examples/voxl-gpio.c

If you need more help, please let me know which direction you want to go.

Alex

Jeremy Frederick

@Alex-Kushleyev I'm specifically interested in toggling the VTX on/off GPIO on the ESC as described in the attached image.

Alex Kushleyev

@Jeremy-Frederick , got it. one more question, are you looking for a way to toggle it while PX4 is running or not running?

The reason why i ask is that the command message for this action has to go through the serial port connecting to the ESC and if PX4 is running, then it opens the port and the command has to go through px4.

Here is how you can test:

first make sure that the function works without px4:
- run this script https://gitlab.com/voxl-public/voxl-sdk/utilities/voxl-esc/-/blob/master/voxl-esc-tools/voxl-esc-gpio.py with --val 0 or --val 1 options and check to see if the aux power is turning on / off. currently this script is only set up to toggle this pin on M0138 FPV ESC, but in future we will expand support to other GPIO on ESCs if needed
- for example, python3 voxl-esc-gpio.py --val 0
- you should have this script on voxl already in /usr/share/modalai/voxl-esc-tools or you can clone the repo to voxl2.

I will need to double check with the team how this can be triggered via PX4.

Alex

Jeremy Frederick

@Alex-Kushleyev Yeah, even if we can't trigger it through PX4, having to stop voxl-px4 will not work

tom

@Jeremy-Frederick To enable the feature, set the px4 paramster GPIO_CTL_CH to a value between 1-6 and set the corresponding RC_MAP_AUX# to the button/switch you want to use.

Jeremy Frederick

@tom Seems like neither the voxl-esc-gpio.py test script or the PX4 triggering via RC_AUX seems to be having an effect on the PF0 GPIO on the ESC. Currently, I am using SDK 1.3.5. I did notice that the voxl-esc-gpio.py has the packet = wrap_data(ESC_PACKET_TYPE_GPIO_CMD,req_data) line commented out, is there anything else that I should check? Perhaps a different ESC firmware?

tom

@Jeremy-Frederick The feature should be supported on that release and ESC firmware as long as you have run voxl-configure-mpa in order to load the ESC firmware contained in the release.

To confirm, you have something similar setup:

GPIO_CTL_CH = 2
RC_MAP_AUX2 = 10

where 10 is the channel of the button or switch on your transmitter that you'd like to use to toggle?

There was another bug that was fixed later where if VOXL_ESC_MODE is set to 1 (turtle mode) this would not work, can you check that as well

Alex Kushleyev

@Jeremy-Frederick , the python test script works, you may have an older version of it, we had commented out something by accident (the line you mentioned), but it is fixed now : https://gitlab.com/voxl-public/voxl-sdk/utilities/voxl-esc/-/blob/master/voxl-esc-tools/voxl-esc-gpio.py

Double check that you have ESC firmware 39.18 and should be good to test with python script while px4 is not running (as a first step). then you can set up your channel mapping as Tom suggested..

Hopefully that works for you!

Alex