I’m student instructing our universities Systems Engineering course, I have a background building/flying/(mostly crashing) FPV quads so that’s where my experience comes from, and I’ve been working on the universites drones for a few years now, my main project right now is to upgrade an old Tarot X8 II build to a Holybro pixhawk 6x, and I personally want to upgrade the suspect esc’s that came with the kit to something a little more reliable and modern,
Almost all of my personal experience is with 4 in 1 escs, (only ever had 2 quads myself with individual esc’s before I moved on from that program), and what seems to me like the perfect fit is a pair of 4in1 escs utilitizing esc telemetry to run current information back to the 6x, this is kind of important as although I’m not sure what the current pull on the tarot is, my professor likes to haul around dummy weight for fun so I’m pretty sure we’re going to be exceeding the 60a cont rating the power modules have, and so using escs as basically extra power modules seems perfect, and 4in1 escs are so cheap it all seems great,
Problem is that I can’t find any information on which 4in1 escs have individual shunt resistors for digital current telemetry through the telemetry pin (and not just a single shunt resistor for current sensing over the analog pin) from forum posts I’ve read some do have them and some don’t, should I try to use the analog current sensing one way or another? maybe just build my own powder module thats capable of the current? (I mean shunt resistors are not rocket science, and if I was on a pixhawk 6c or something setup from the get go for analog current sensing that’s probably what I would do, but the 6x still has adc capability)
Any help? should I avoid 4in1’s all together and do something else? 4in1’s are just like half the price of going with individual esc’s
Very few. I have one, an Airbot Ori32 but even reading the available specs you wouldn’t know it. Looking at the ESC though it’s clear that it does and the data is there in telemetry.
Does that have a traditional ‘curr’ pin? I don’t see the fifth shunt resistor that would make that possible (unless its on the other side of course)
And yeah I was sort of afraid it would come down to inspecting escs.
Documentation on all of this stuff is so sparse, and this big multirotor stuff is all so different than the fpv hardware its insane (like why is double sided foam tape the standard way of holding like everything down, like i buy a $400+ flight controller and they ship it with double sided foam tape?? something wrong with bolts and damping gummies?)
No. I have never seen one with shunt resistors on each ESC and one on the power input. You get summed current from the Battery Monitor anyway.
Most of those have internally damped IMU’s and in many cases foam tape is all you need. Hex used to say that all Cube applications should be “hard mounted” (meaning with the supplied tape) but that’s not really true, it depends on the rigidity of the frame.
Should say thank you as I realize I didn’t in my last comment,
Yeah, I’m sort of thinking shopping for a 4in1 with individual shunts is basically going to be shopping for one without a curr pin…
And I get that foam tape is all you need but like don’t even give me the option to bolt the thing down? I guess their trying to keep people from bolting it down solidly which is probably worse than the foam tape
Sort of dumb in my “what are people doing” question to not mention that I’m aware individual ESC telemetry should work just fine provided the ESC has a shunt resistor of course,
I’m not against going with individual ESC’s but they’re double the cost and require a pretty hefty pdb etc… I mean in theory they’re probably more serviceable but then this octocopter has only been flown on one occasion since it was built 2 years ago, the current plan is to get it up to a standard we’re putting together and we’re building 3 much smaller hexacopters to the same standard this semester, and then lighter payloads/short mission times can be flown on the hexacopters and then if needed mission payloads can be bolted up to the octocopter (hence the standard, standard bolt pattern, standard flight controller etc…) if needed since we already own the thing
What are you’re thoughts on using an ADS1115 to take the ‘curr’ pin of a pair of traditional 4in1’s and run into into like the Power2 port? (using a holybro power module on the power1 port for all the other current sensing and other goodies…)
I’ve read all I can find on it and it seems fairly trivial and doable and it seems like a couple other folks are doing it which means the ads1115 should be supported?
The holybro documentation recommends using one on PX4 but noticably doesn’t mention Arducopter (its like “if using PX4 and you can’t use a digital PM than use a ADS1115 and an analog PM” it doesn’t say it doesn’t work with Arducopter but it also doesn’t say it does work with arducopter…)
Also anyone know what the recommended voltages to put into the POWER ports on the 6x are? The documentation has this to say:
Priority: Brick1>Brick2>VBUS
Over Voltage: 5.85V
Under Voltage: 3.81V
HYS: 30mV
I’m just curious why all the PM’s are like 5.2 or 5.35V or something other than the standard 5v?
(would probably plan on prototyping this for a flight or two using dev boards and then actually spin up a pcb if it worked…)
