Software On/Off VTX Power using VOXL FPV 4in1 ESC
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Hi all,
Looking for guidance on wiring my FatShark Aura Analog VTX module to my FPV 4in1 ESC. I would like to take advantage of the software defined power switching mentioned in the datasheet, however, it is unclear to me where exactly on the ESC I need to solder my leads to in order to use this feature.
Please advise. Thanks!
For reference (link to datasheet) :
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Update:
I did find this (link) old post on the forums from 2024. From what I can gather, the voxl-esc-gpio.py command is supposed to be configured to toggle the AUX power pad on the ESC. However, even though I am running the script with the --val flag alternating between 0 and 1, I see 3.3V on that pad at all times. Maybe I have something incorrectly configured here? The 3.3V reading is confusing because per the previous forum discussion this script is supposed to be for VTX power, but I would expect a VTX power source to be battery voltage per the documentationCurrently, I'm just trying to test this in the CLI right now. I am eventually wanting this to work concurrently with PX4.
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The post you found should still be applicable. Can you check which firmware is installed on your M0138 FPV ESC.
Also, It looks like you are doing the measurement in the wrong location. The switchable (on/off) power output is a 4S regulated supply that is available at pads right near the yellow payload connector. Note that the output from the yellow connector is not switchable, just VBATT. but the pads labeled <4SOUT> are switchable and you can test using that gpio script.
I circled the pads that you need to use in RED:
from the voxl-esc-gpio.py test script,
Controls AUX regulator on M0138 ESC ID0, unsupported on other ESCsI see your confusion that it mentions "AUX regulator", it is a misnomer, because the ESC also has an auxiliary 3.0 / 5.0V regulator (only 500mA).
So if you are powering a VTX, you definitely need the 4S output, but also keep in mind it's about 500mA max as well. Is your battery voltage 4S or 6S?
After you test while PX4 is not running, just directly talking to the ESC using
voxl-esctools, we can discuss how to do this while PX4 is running (assuming you are using px4).Alex
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Thanks for your reply. I ended up just writing a small bash script to toggle the pad. I then probed all the exposed pads on the ESC in order to find which one was toggling battery voltage, so I did discover the correct pads as you have circled above. If you're open to the suggestion, I might make this more explicit in the documentation is it is not very obvious at first read. Maybe including the above picture would suffice since there's no labeling in the docs or on the silkscreen that makes this explicit.
My battery voltage is 6S. I do have concerns about the total current draw being capped at 500mA. My VTX module pulls 500mA at baseline, and I've observed in the field it pulling up to 600mA when transmitting at full power. I will have to rethink my harness design if I am truly limited to only 500mA.
I am going to attempt the PX4 integration using my hand controller and will report back if I have troubles. If you do have any notes on how to set that all up please do let me know.
Again, very appreciative of your reply. Thanks!
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Okay, so after tinkering a bit yesterday, I've been unable to figure out the aux button mapping process. Could you kind of walk through a step by step on what exactly I need to configure? I think what I am most confused on is what on my RadioMaster GX12 transmitter counts as an "AUX button". I initially though the 1-6 buttons, but those all seem bound to flight modes so I am not really sure.
Appreciative of your help!
