Two steps forward, one (big) step back; that's the current situation with the ECU resetting itself.
To eliminate the possibility that the USB cable was somehow receiving interference from something electrical on the bike, causing the software to detect a reset, I made a bluetooth adapter to use in its place. I had a spare serial-to-bluetooth adapter from a previous upgrade on a 3d printer and a very common chinese buck converter (feed in any voltage up to the chip's limit, it will output a stable, selectable voltage. I just had to buzz out which wires were transmit, receive, power, and ground. Luckily the aliexpress ECU outputs serial data at 3.3 volts, the same voltage that the bluetooth adapter uses so I didn't need to use a voltage-level shifter. Now I just need to package it up, neat-and-tidy in some small box or something... I'll find something.
The adapter works with my laptop's internal BT communicating with the tuning software, on two of my cellphones, but not on a usb-bluetooth dongle I use for my main PC. Oh well, I intend to do the majority of tuning on my laptop. However, even with the wireless connection to the ECU, the resets were still happening...
My initial assumption that the ECU reset was caused by the starter motor were wrong. I discovered that if I turn the engine over using any method (e-starter, kickstart, socket/ratchet on the crank bolt) while the kill switch is in the RUN position, the ECU resets itself. When the kill switch is in the STOP position, it grounds the signal coming from the trigger coil; when it is in the RUN position, it has no effect on the trigger coil. So, it is the trigger coil itself that is causing the resets.
My first thought was that one of the two wires coming from the trigger coil is grounded, when usually in EFI systems both wires go back to the ECU. The manual for the microsquirt states: "...The Microsquirt measures the voltage from the sensor and converts it into a temperature, position etc. reading. If that sensor is grounded to anything other than the Microsquirt itself, then that input voltage will be altered by any external voltage drops. ...Tach input (e.g. crank, cam sensors) will be even worse - they can show false or missed teeth and cause syncloss due to the ground voltage difference..." The aliexpress ECU does not have a ground wire for the trigger coil to attach to. Without an rpm signal, an ECU is worse than a paperweight. I decided in order to give the aliexpress ECU the best shot at working, I had to crack open the case and solder a new wire to a good ground point. Opening the case was quite easy. 6 small screws and some lightly adhesive conformal coating was all that held it together. My first reaction was... Dang, these motoEFI guys (the tuning software and the ECU firmware are both have their names in them) even had a custom PCB created. I absolutely thought that the board inside the case was going to be a clone of one of
this or this. Nope, looks like they (motoefi) have put on the PCB only what is needed to run a one cylinder engine on a particular configuration without many of the extra features like knock sensors, vehicle speed input, flex fuel, etc. Also, the I'm guessing... mosfets? they are using to switch the injector and the fuel pump aren't connected to any heatsink. One of them has a very small piece of metal adhered to it as an added thermal mass and the other one had nothing on it at all. The soldering is IMHO, just passable - the solder joints look very dry (lack of flux), maybe even hand-soldered. The main IC had its name scratched off, as did one of the suspected mosfets.
After having taken a good look at the ECU PCB, considering options, trying to filter/condition/shield the signal from the trigger coil, and many other things, I have decided to stop using the aliexpress ECU if I cannot get this issue solved with minimal extra cost or effort. I still have a few ideas in my head that I think
might do something, but if the problem is what I think it is, I and possibly other people who buy this kit will have to buy a $25-$70 circuit board that will condition the trigger coil signal and/or a oscilloscope to see what output the trigger coil is giving in their particular case and filter it as needed. Either way you are spending time or money or even both. Sorry dudes, but at least in my case it looks like the ECU from aliexpress won't work without monetary or time investment that is equal to buying a real/genuine/brand-name ECU. I hate to stop using the ECU before I even get to try and start the engine, but as I said above, without an RPM signal, an ECU is worse than a paperweight. The other hardware and sensors from the seller seem to be working fine. This kit may still be a viable option if you just need everything except the ECU, as I did. I had a heck of a time searching the internet for a small-engine-sized throttle body. There were only a few sellers and most of them had odd/different mounting points where the TB bolts to the intake manifold. Ecotrons is an option, but their small engine EFI kit is $600, the tuning software is, in my experience, difficult and unintuitive to use, and I doubt you could purchase all the supporting hardware minus the ECU for less than the aliexpress kit.
After I try all that I can to get the aliexpress ECU to accept a trigger coil input and mapped out which wire goes to what thing, I'm going to need to re-run and maybe re-wire most of the EFI harness. At the time I wires the bike, there were no thoughts given to keep high power wires and sources of noise isolated and apart from low power signal wires, the wires from the ECU were to short to have anything but a rats nest. I'll also have to try and keep electrically noisy parts like the regulator/rectifier, wideband controller, ignition coil & lead, fuel pump, CDI, and relays to one end/side of the bike and the sensitive stuff on the opposite side/end. I'll also need to get proper water-resistant connectors and wire whose gauge size is suitable for how much current it will carry. And a crimp tool. And wire shielding sleeves. And heat shrink tubing. And a "real" fuse/relay box. And blackjack. And hookers. Time to save up...
So much for that teeny tiny little left to do/buy list.
I'm actually starting to wonder if I will get this done before warmer weather starts to appear...