Feeler - Touchscreen OBC with Megasquirt CAN interface, extra sensors, outputs, etc.

[bbushree]

First, I love what's going on in this thread and I am intrigued. I just joined the forum and I have slightly different use-cases but I would like to collaborate on this if possible.

I am in the middle of doing a CA legal (hopefully) S54 swap and have been completely unable to find an off-the-shelf solution to the 'expose the check engine' problem that California requires me to have. Someone used to offer one that handled the AC control and check-engine light in the attached link but the guy selling them has become unresponsive. I'm not using Megasquirt, just stock ECU setup for the S54 which I've found ample documentation on already.

I was about to venture off on my own into the CAN bus microcontroller wilderness until I started asking myself what else could I build into this unit given the data available from my ECU. And after searching around to see if anyone was replacing their OBCs, I found this thread.

Question to you mikey.antonakakis - besides the functionality you've already built into this unit, do you think this would be something worth pursuing? Seems like you already have a CAN receiver and a CAN transmitter? I have some software experience and would love to try to take a stab at it if you think it's doable.

[mikey.antonakakis]

No updates other than "this isn't dead!". Lots of cold/snow this winter and baby at home has things on backburner until spring most likely (haven't done anything e30-related in a while now). As the weather warms up this spring I will be itching to get the car to the drag strip and dyno so this project will pick back up around that time :) non-zero chance I order rev2 PCBs sometime before then, but no promises.
In the meantime if anyone is interested in doing a pilot/trial on these let me know, as I have a few not-perfect boards just sitting around right now. I can work on this project while it's cold out even if I'm not taking the car out! Just need a little fire under the butt etc.

[mikey.antonakakis]

It's not a race, glad you are still working on it as time allows.

Right now are you set up for a single EGT, or plan to run one per cylinder?
Individual EGTs sound fantastic for a tuning geek like me, but are probably more trouble then they're worth unless you're building an engine for competition.

Just a single at the turbo inlet for my setup. It would technically be doable to have individual, but that is definitely pricey. At DIYAutoTune prices that’s like $500 for thermocouples alone - then at least with the amp I’m using, 5 more of them on the PCB. I’m sure there are multi-channel amps available though. As for the data side, if you wanted to log to Megasquirt 2 for instance, that would tie up 6 of the 8 GPIOADC channels on the CAN bus (not familiar enough with MS3 to know if that has more of those channels available).

[Panici]

Things have been slow on this front due to other aspects of life (and colder weather keeping me away from the e30 for a while, baby just turned a year old and is a full time job to keep him entertained lol). But some PCB revisions have been made. Want to do a few more.

It's not a race, glad you are still working on it as time allows.

Right now are you set up for a single EGT, or plan to run one per cylinder?
Individual EGTs sound fantastic for a tuning geek like me, but are probably more trouble then they're worth unless you're building an engine for competition.

[mikey.antonakakis]

Things have been slow on this front due to other aspects of life (and colder weather keeping me away from the e30 for a while, baby just turned a year old and is a full time job to keep him entertained lol). But some PCB revisions have been made. Want to do a few more. So far the following is updated in the PCB design:

• Minor revisions to fix minor issues (e.g. through holes were a little tight, logic level shifter changed to a different one to work better with the VR signal conditioner)
• EGT sensor amplifier/digitizer added
• Research started on knock sensor module (will enable monitoring knock digitally, e.g. knock counts, threshold adjustment, etc).

[mikey.antonakakis]

Working on my own e30 has slowed down the progress on this a bit - BUT the efforts on my car have highlighted a few solid ideas for a second revision:

• fix minor issues with the first run of boards (e.g. slightly wrong version of logic level shifter chip for the VR signal conditioner)
• analog sensor low-pass filter circuits
• EGT probe amplifier/digitizer chip
• knock sensor signal conditioning chip?

In any case, it’s working great on my car despite the minor
issues/mistakes.

[mikey.antonakakis]

nando Re: supporting other ECUs - definitely has crossed my mind. More generally this is a CAN-enabled powerful microcontroller breakout board with extra I/O capabilities. For example it should be able to run a couple boost control solenoids by just configuring a couple jumper wires to set up the transistor switch circuits.

More updates soon, mine is installed in my car and the user errors should be sorted out. First test drive with hopefully no bugs coming today.

[Panici]

Does Speeduino support CAN? I'd suspect it does by now. Seems like it would be relatively simple to adapt, given you should have control over everything.

FYI, I've ran Megasquirt in my only daily-driver for over 10 years, and for 15 years in total. The hardware and software, has never, ever, been a problem.

I built my first Megasquirt in 2005 for a friend; my first MS2 in 2007, and my current MS3+X back in 2011 (I was probably the first in the E30 community to run one). I have literally not touched the MS3+X once since 2012, when I finished the tune. It still runs great today.

Not sure about Speeduino CAN support. From what I can see in the documentation it is supported, but I've never tested to see if it actually works.

Glad to hear about the reliability of your MS3X, hope for years of trouble free operation in my E30 as well.

Time will tell how the Speeduino holds up. I've had some hardware/software issues, but for the pricepoint I can't complain. I've been daily driving it for two summers now and it hasn't left me stranded yet so that's what counts.

[nando]

Late to this thread.. really cool product! I like the idea of a check panel version - which is probably the thing I look at the least in my E30 (therefore, I'd be more willing to give it up for a cool project like this). Using CAN is a good place to start, because by now, basically everything should support CAN of some sort - including factory swaps that use stock DMEs. It doesn't have to be Megasquirt specific, you can just add support as needed.

I think Megasquirt generally gets away without shielding as they advise to route signal wires away from ignition leads etc. And a lot of folks making their own wiring harnesses heed this advice.
Indeed on my MS3X (where I scratch built the engine loom) I have good data quality coming into the logger. Although I haven't hooked a 'scope up to the signal wires to see what is electrically present vs what is filtered out on the megasquirt side.

I can tell you that in my miata running a Speeduino (arduino-based ecu) on the mostly factory harness, there is sensor noise. The speeduino is a hobbyist product (and the price-point is fantastic), so I'm not expecting commercial quality out of it when connected to 30+ year old wiring.
The system is definitely still usable and tunable though, and that is what matters.
IMO with modern hardware we are asking for more then what the original ECU would have demanded in terms of signal quality.


Thinking out loud here about possibilities: What happens when the battery loses a negative terminal when running, and the alternator output isn't filtered by the battery? Or what about a failing voltage regulator on the alternator? People running high-energy ignition systems? Analog sensor wires get shorted to +12v when hooked up incorrectly?

Check out some of the tech used in the rugged arduino boards by these guys for some ideas: https://www.rugged-circuits.com/


All that said, you're designing and building a hobbyist product for a niche market, and it doesn't have to be perfect. As long as it doesn't fail spectacularly and set things on fire, the other points are probably moot to everyone except us nerds.

I'm definitely a nerd, and I don't want to downplay your experience; it sounds like you've had quite a lot of success. But IMO, you don't need a scope to build your harness for Megasquirt, or worry about shielding or shorts or voltage regulators or fancy shit normal people don't know about, especially with an adapted stock harness. The default Megasquirt board will work perfectly fine for years without issues, if assembled properly (cold solder joints are probably the biggest issue). There can be issues, but it's almost never going to be something a fellow nerd is going to care about.

Does Speeduino support CAN? I'd suspect it does by now. Seems like it would be relatively simple to adapt, given you should have control over everything.

FYI, I've ran Megasquirt in my only daily-driver for over 10 years, and for 15 years in total. The hardware and software, has never, ever, been a problem. The rare issues I've had have always been my own damn fault (wrong pins, broken wires, bad relays, etc). And ironically, my E30 has consistently been the car that *always* works - barring a dead battery (since I don't drive it as much now).

I built my first Megasquirt in 2005 for a friend; my first MS2 in 2007, and my current MS3+X back in 2011 (I was probably the first in the E30 community to run one). I have literally not touched the MS3+X once since 2012, when I finished the tune. It still runs great today. My biggest problem now is the original laptop I used to tune it died years ago, so if i wanted to update it, I'd have to start from scratch, lol!

[mikey.antonakakis]

Found the first hiccup. Got the new setup installed in the car, powers on just fine, but the USB data connection from the Teensy to my laptop wasn't working.
The Teensy 4.0 has USB pads on the bottom of the board that I designed the PCB to tap into - unfortunately they are for the Teensy's *second* USB port, which cannot be used to flash firmware onto it. Oops.

Not a big deal though - relatively easy fix, I'll just use the Teensy's USB micro USB connector with a short pigtail, and solder the pigtail to the appropriate pins on the DTM connector. I'll add a USB port to the next iteration of the board, or if I can fit it, modify the case to accept a USB bulkhead connector. Either way, the idea would be to run a short USB cable internally, then either add a USB cable to the DTM harness, or simply plug in a cable from the laptop to the bulkhead connector.

[mikey.antonakakis]

Got my personal board configured for my application. This configuration is mostly internally connecting the 12-pin Deutsch DTM bulkhead connectors to the desired microcontroller pins, and if there are switching circuits (like for my boost control solenoids), jumpering between microcontroller pins and transistor circuit breakouts, then from the transistors to the DTM connector pins.

Notice that I was also able to add another breakout board to add an exhaust gas temperature thermocouple - this is a thermocouple amplifier and ADC, and the thermocouple will go directly into the DTM pins for simpler external wiring. No reason I couldn't have run this breakout board externally, but for my setup this came out cleaner and used fewer of the DTM pins (I'm using all 24!).

[Panici]

Thanks for the update.
Slow and steady wins the race.

[mikey.antonakakis]

Next steps: build harnesses, including a USB cable for the Teensy interface (for uploading sketches, serial monitor output, etc.). Thinking I will try to find ~6ft USB-A male cable to integrate directly to the harness, so you can just plug it right into a tuning laptop.

[mikey.antonakakis]

This has not died! Got slowed down for a while (infant son, work travel, house projects, etc.). Just soldered up 5 boards, which involved adding the Deutsch connectors, the VR signal conditioner (0.5mm pitch, didn't leave a ton of room to access the pins so it was kind of tricky), and the Teensy boards.

Just got 13 spools of 100ft each of 20ga TXL wire, should be sufficient for any circuits on this board (2% voltage drop at 5ft and 5 amps). Will use this to make flying lead harnesses for the kits.

[Panici]

Boards got here early. Pretty ridiculous that I can order custom PCBs, with SMD assembly, on a Friday, and have them the next Friday from China.

Looks killer, love the translucent case!