I’m thinking of trying out eliminating the current sensor on a simple quad-copter using a 4-in-1 ESC.
My understanding is that the telemetry port on a 4-in-1 ESC has both voltage and current data - among other things. I believe this can be accessed connecting the ESC’s telemetry output to a serial port’s RX pin, and by then setting SERIALn_PROTOCOL=16,
The ESC configuration software may have a parameter to set for enabling telemetry output.
It also appears that the BATTERY_MONITOR=9 should be set for ESC.
Do I have this about right? Or are there other settings.
If the data is digital, I’m guessing that parameter such as the amp-per-volt and voltage-multiplier parameters are unnecessary.
Is there a wiki about how to configure this properly? Are my assumptions correct?
As @amilcarlucas said. There are very few 4-in-1 ESC’s that have current data in the telemetry stream. Chances are you don’t have one. If there is a shunt resistor for each section of the ESC then it might have current data. I have one of these. If it’s a common shunt resistor on the battery input then it won’t. Most units are of this type so it’s analog current out only.
As it happens, I don’t think I’ll need current data.
I’m thinking of super simple small quad, and using only voltage for a battery failsafe. So if I can get voltage data, and RPM for a notch filter, I’d be in good shape.
My remaining question is the impact on COMPASS_MOT_(CT, X, Y, Z) if there is no current data. I may have to eliminate those parameters in compass calibration. (I use MavExplorer’s MagFit to get these values.)
Sure, use the analog current output from the 4-in-1. Most Flight Controllers have an input for that. What FC are you using? And which 4-in-1 for that matter?
And right, no useful compass mot w/o current.
Here is an example of the 4-in-1 I mentioned. Note the shunt resistors at each corner.
Thanks Dave - yes, the Analog current pin is an option. Just a bit of nuisance to calibrate.
On my workbench right now are T-Motor F45A 20x20 ESC’s, running BLHeli_32. But I’d have preferred using a less expensive ESC running BLHeli_S - but most of them are back ordered right now.
I’m using the Holybro Pixhawk 6C Mini.
I’m an advisor to a small outfit called iVue Robotics. Using their Develop-Air Mini as a basis for my ideas, I designed my own 3D (FDM) printed quad-copter designed to use inexpensive 2312 motors. I’ve made several improvements aimed at making the copter simpler and less expensive.
I find that only takes a couple of flight/charge cycles and it’s done with logged/charged ratiometric amps/volt method. For all practical purposes this is all you need to do.
I see a 20x20 55A iFlight Blheli_S ESC on RaceDayQuads for $37 in stock. I like their stuff, I would use this if I was building a 20x20 stack.
Yep - not difficult - but a nuisance. Especially for a new builder.
I’ve good success with the tiny and inexpensive Mateksys current sensor with an I2C feed to the flight controller. Super accurate even at very low loads, and requires no calibration. I was hoping to find something even simpler than this using the ESC’s functions/outputs.
AM32 DroneCAN ESCs should provide individual motor voltage and current I think. I’m experimenting with the ones from VimDrones which are shown on this AP wiki page. I’m also hoping that I can get away without the regular power module in order to save a little bit of weight
