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

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  • nando
    replied

    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.

    Originally posted by Panici View Post
    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!

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  • mikey.antonakakis
    replied
    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.

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  • mikey.antonakakis
    replied
    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!).

    Click image for larger version  Name:	IMG_3682.jpg Views:	6 Size:	78.5 KB ID:	10069012

    Click image for larger version  Name:	IMG_3684.jpg Views:	4 Size:	75.8 KB ID:	10069010

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  • Panici
    replied
    Thanks for the update.
    Slow and steady wins the race.

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  • mikey.antonakakis
    replied
    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.

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  • mikey.antonakakis
    replied
    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.

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  • Panici
    replied
    Originally posted by mikey.antonakakis View Post
    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!

    Leave a comment:


  • mikey.antonakakis
    replied
    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.

    Untitled by Mikey Antonakakis, on Flickr

    Untitled by Mikey Antonakakis, on Flickr

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  • mikey.antonakakis
    replied
    Big order from DigiKey arrived yesterday, and an order of Deutsch Connectors are out for delivery today. PCBs should be here Tuesday!

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  • mikey.antonakakis
    replied
    Also, PCBs have finished production and awaiting DHL pickup. Need to place a DigiKey order tonight for various odds and ends, such as the Teensy boards, pin headers, etc.

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  • mikey.antonakakis
    replied
    Originally posted by JehTehsus View Post
    This is very cool - are you planning on conformal coating the boards? I am trying to pin down whether or not I want to go the conformal route for my check panel project.
    Thanks! Your project is looking pretty awesome too!
    Wasn't planning on conformal coating - mine is designed more as a development board, where the user can configure to their use case using jumper wires (or I can configure for them). It will be going in a sealed enclosure (sealed enclosure with a vent is another option), so water ingress should not be an issue.

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  • JehTehsus
    replied
    This is very cool - are you planning on conformal coating the boards? I am trying to pin down whether or not I want to go the conformal route for my check panel project.

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  • mikey.antonakakis
    replied
    Order placed for 15 PCBs! Should have in 2 weeks (maybe sooner).

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  • mikey.antonakakis
    replied
    Board revision finished, maybe. Need to go back and double-check some stuff, make sure I'm not forgetting anything. I think I may order 15 of these to start.
    I will have to order the VR sensor signal conditioner IC separately and solder by hand. Nothing spells fun like 0.5mm pitch surface-mount soldering!

    Capture by Mikey Antonakakis, on Flickr

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  • Panici
    replied
    Originally posted by mikey.antonakakis View Post
    PCB design updates well underway. Kind of a lot to it, so far I have the schematic updated and I still need to redo the actual layout. But, I am having a design review today with the design firm that's helping with the PCBs I've done at work, so their recommendations will get rolled into this one.
    Oh, it's getting a 3-axis accelerometer, too (ADXL362, +/-8g max). No gyro/magnetometer on this one - I haven't found any with good analog signal processing before they digitize it. Gyro would really only be helpful if you really wanted to record yaw rate.
    This project has me hyped!

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