RCMF Donations

Enjoy using RCMF? How about a wee donation to help us keep you in the style to which you've become accustomed?

Welcome to RCMF. Please login or sign up.

October 21, 2020, 17:26:59 pm

Login with username, password and session length

FrSky Neuron Speed Controllers (mini review)

Started by PDR, June 25, 2020, 10:44:41 am

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.


Having recently changed my main Tx to a FrSky Horus I looked at these speed controllers because they have extremely useful embedded telemetry. For example if you plug the S-Port connector into a FrSky Rx you will get Voltages (flight battery, Rx Battery, BEC), Currents (motor and BEC), Power(mAh) consumed, ESC Temperature, motor RPM. They also have a huge range of selectable/adjustable settings (including BEC voltage which can be set anywhere from 5 - 8.4v). The particularly useful one of these is the Power Consumption. Pack voltage is a poor indication of remaining charge in a large lipo, and so this allows me to set a fairly accurate electric fuel gauge with an alarm at (say) 4,000mAh consumed from a 5,000mAh pack.

These ESCs come in two types and a range of sizes. The standard (black) ones are about double the size and weight of the newer "S"(red) versions, but the S-types only come in 40 and 60 amp versions while the originals had an 80A (120 peak), and have robust machined aluminium cases for both strength and heat-sinking. They are all the same size - that is to say the standard ones are the same size and weight for the 40, 60 and 80A versions and the two S-types are the same size and weight as each other (about half that of the standard ones). There also isn't that much of a price difference between them (the cheapest 40 amp one is £45 while the most expensive 80amp one is £63, and the difference between the 40S and 60S is about a fiver).

So I got one of the 80Amp ones for my AcroWot - I actually needed the extra weight, and couldn't see any point in getting the lower rating for the price. It arrived in a nice plastic box but with no connectors fitted. One of the first things to grab my attention was that it doesn't have a lead to go to the Rx - it has a pair of servo-lead *sockets* (Rx and Smart Port) instead. So you may need a couple of plug-to-plug servo leads - I feel these could have been supplied in the box! But that aside the impression is of a very sold, well-made unit with a decent build quality.

I mentioned the plethora of adjustable settings. Unlike other ESCs these are not set with throttle movements or a programming card, but are set from a piece of software called "BLHeli_32" that you have to download. To use it you also need a USB-linker" device (available from T9 for £6.60 - cheaper alternatives are available but you need to know what you're doing to choose one). This adjusts everything other than the BEC voltage, which is adjusted via a LAU script in an OpenTx transmitter. You can just plug it in and use it, and it will work (including the telemetry), but it will probably have the prop-brake set to on (fine of you're a gliderist with a folding prop or a multicopter flyer, less-so for normal people).

Also in the box is the manual (two sides of A4) which, like most FrSky documentation, pretty hopeless - especially on how to use the USB-linker. This took me some research and head-scratching (because some aspects of it are unexpected and counter-intuitive) so at the bottom of this post I've included step-by-step instructions so that they're written down where people can find them!

Once you have it connected you get this delicious set of things to play with:

BLHeliSuite32ESC Setup_200625_1.png

The full details of what they all do can be found in the manual (in a PDF under the "BLHeli_32 Info" menu. Things to note include that the range of options presented will depend on what ESC is connected, and that most of these ESCs seem to be shipped with the prop brake or "damping" (this setting only appears when certain ESCs are connected) set to "on". So if you're a normal fixed-wing user with a non-folding prop you'll want to change this. I believe they default it to on because a lot of FrSky customers are multicopterists, and they like to have "throttle damping" because it slows motors down quicker and thus gives them better control response. In some cases this menu item appears as "Regenerative braking/damping" which seems to imply that the ESC can actually put energy back into the batteries - an interesting idea that I have no way of testing. Lots of these settings can be ignored by the typical sport user - they're included so competition flyers can fully optimise their setups and for the inveterate, compulsive tinkerers who tend to be attracted to FrSky kit!

Anyway - my overall conclusion after one evening of head-scratching followed by success is that this is an excellent piece of kit whose telemetry functions offset the slightly higher price and will allow be to operate my larger electric models with a much better understanding of how much duration remains in the battery!

How to use the USB Linker with BLHeli_32
I appreciate that to some who speak arduino the following is a "well DUH!", but the information isn't in the manuals so I thought I'd add it as a summary in case anyone else comes at it for the first time and searches for help.
The Process goes like this:

Before you start plug the USB Linker into your PC and confirm that there's a driver for it. When you plug it in Windows should recognise it and announce it exists. If Windows doesn't seem to recognise it, or it it doesn't seem to work when you follow the steps below, you may need to manually install the driver. Go into Windows Device Manager and look down the list for Ports - expand this branch and you should see something like "Silicon Labs CP210 UART bridge" with a Com Port number. If you don't then ask Mr Google for a "Silicon Labs CP210 UART bridge driver" - choose the option from the Silicon Labs website and download/install the driver in accordance with the instructions.

1. The S-Port and Rx leads must BOTH be disconnected from the ESC

2. The programming lead from the USB linker goes into the PWM port (ie the normal one from the Rx, not the telemetry port)

3. The programming lead MUST have the +ve pin (the middle one) disconnected

4. Plug the USB linker into your PC and fire up BLHeli32 (suggest you maximise it so that bits of the window aren't hidden beyond the bottom of the screen)

5. After firing up BLHeli32 you must find the top Windows menu bar (above the tabs) and open the "Select BLHeli_32 Interface" menu and select "BLHeli32 Bootloader (USB/Com)"

6. At the very bottom of the screen there's a box labelled "Port" - click the down-arrow and select the one from the list which includes the words "Silicon Labs CP210 UART bridge" or similar (ignore the "baud"  box - this is automatic).

7. WITH THE ESC DISCONNECTED FROM THE FLIGHT BATTERY connect the programming lead from the USB Linker to the PWM port of the ESC.

8. In BLHeli32 click on the "connect" button (at the bottom of the screen next to the "Port" and "Baud" boxes. The screen will ask you to power-up the ESC - do this by connecting a flight battery. If you're too slow it will stop trying - just press connect again and this time connect the flight battery more quickly! It will announce success and the "connect" button will change to a "disconnect" button.

9. Click on the "Read Setup" button (above the Ports box at the bottom of the screen). It should load all the data from the ESC including its type and settings.

You can now make whatever settings changes you wish. You can also give the ESC a specific name (a good idea if you have more than one). You can save settings in files on the PC using the top menu "ESC Setup" and load them again later. There are other options for working with multiple ESCs - these are for multicopter use, Instructions on what all the settings do can be found in the "BLHeli_32 Info" menu which links to a PDF copy of the manual.

10. When you have made your settings changes click on the "Write Setup" button (next to the Read Setup button at the bottom of the screen). Do not use the "Flash BLHeli" button - I assume this is for updating the ESC firmware itself, which is a very different thing.

11. Now click on "Disconnect", and when it has done so (indicated by the button changing back to "connect" you can unplug the flight battery, then unplug the programming lead and then reconnect the PWM lead from the Rx (and the S-Port lead if you're using it).

I've managed to make that sound very involved - it isn't. The second time you do it it's obvious - it's just a series of very simple steps. I wasted a lot of time doing an Eric Morecombe - I was doing the right steps, but not necessarily in the right order...

There are no shortcuts on the long, hard road to success. But if your dad's rich there could a limo service...


It's worth looking at Rampup Power and Low RPM Power Protect too as some users have found this limits max power available in certain setups.  The first time I closed the throttle on my 1300W UltraStick I didn't know about Undamped Mode and the damn thing stopped so quickly I thought it would rip the nose off!
I think the smaller Neuron S versions come with the USB linker.  Unfortunately they don't come with a power lead either so you need suitable length heavy duty male to male cables handy.
flying's easy - it's getting it back down in one piece that's the hard part


I tried some power tests today and found that it seemed to be limiting at around 33 amps, so I suspect that I need to look at the ramp-up power parameter. Too warm to play with it today - I'll try it over the weekend.

There are no shortcuts on the long, hard road to success. But if your dad's rich there could a limo service...


New runs today with a freshly charged battery. I turned off the Low RPM Power Protect option and set the Rampup Power to 100%. I also turned on the data logging (couple to the engine kill switch, so it's logging whenever the throttle is live). This time it didn't mess about - serious grunt all the way to full chat, smooth running and barely breaking a sweat (temperature less than 45degC throughout).

So the Axi4120/18 on a 6s pack (two turnigy 40-50C 3s3000 packs in series) turns a 14-8.5APCe at 9,200rpm and around 58A which (by my sums) works out to around 1300watts (or 1.75BHP if you prefer). That should be enough to be going on with.

There are no shortcuts on the long, hard road to success. But if your dad's rich there could a limo service...


It would be a good idea if this post was saved in the "Tech Articles" section
Basic Research is what I do - when I don't know what I'm doing!.


One other thing I have learned about these controllers is that apparently it is recommended that the S-port connection (the telemetry lead) should be a single wire to the signal pin - no positive (red) or negative (black) wire. Apparently there have been reports of problems with earth looping. I haven't experienced any problem, but can see that it could well be "best practice", so I've changed by wiring accordingly. The S-port socket has no centre (positive) pin anyway, and removing the contact for the negative pin makes the connection a bit floppy, so cut and folded back both positive and negative wires right nect to the connector. I put some heatshrink over each folded wire to avoid shorts, and then put a larger piece of heatshrink over all the wires and the end of the plastic connector body to give it support. The unconnected negative contact grabs nicely and makes a much more stable connection.

There are no shortcuts on the long, hard road to success. But if your dad's rich there could a limo service...