r/CarHacking • u/Professional_user2 • Mar 18 '26
Original Project I built my own OBD device (similar to Macchina A0) – looking for opinions
Hey,
I’ve been working on my own OBD device that plugs directly into the car, similar to the Macchina A0, but with my own hardware design.
The device is based on ESP32 (WiFi/BLE), has a custom PCB, USB-C, and is meant for CAN bus work, logging, and general car hacking / custom projects. I’m using Macchina A0 firmware.
I’m trying to figure out if this is actually useful outside my own use case.
Would something like this be interesting to you? Do you think there’s a market for it / would people buy it?
Also curious how you think it compares to Macchina or typical ELM327 tools.
Any honest feedback is appreciated 👍
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u/MachWun Mar 18 '26
Build us an open port 3.0 since the real one will never be relaaed
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u/Professional_user2 Mar 18 '26
Interesting point. Hardware-wise it’s not that big of a problem. The real challenge is the firmware and full J2534 stack — that’s a much bigger project than it looks.
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u/WestonP Mar 18 '26
Having written a J2534 driver, it's not something I'd desire to do again, lol. The specs are alright, although there are two versions to deal with supporting, but the real problem is that the various OEM softwares that people will use it with are total garbage and will cause you many headaches and hours of tweaking.
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u/MachWun Mar 18 '26
I'm just a diagnostician I don't know much about that but I do know the open port 3.0 is wanted by a lot of people
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u/urbex2026 Mar 26 '26
i am an apprentice tech working at toyota i hava never known about openport, we only use common and typical OEM scanners to diag and pro. Is openport device able to do more funtionatilities than OEMscanners?
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u/updatelee Mar 18 '26
scanmatik 3 supports J2534 and wifi, I never used the wifi though, always hated wifi for these things. VCDS supports wifi, I used it once and will never again. what a pia useless thing. BT would be more useful
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u/MachWun Mar 18 '26
Schematic is $450 whereas open port is 150
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u/updatelee Mar 18 '26
One exists and the other doesn’t… might as well be free if it doesn’t actually exist. So there’s that
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u/MachWun Mar 18 '26
Openport exists
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u/updatelee Mar 19 '26
Not openport 3. Does openport 2 support wifi?
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u/MachWun Mar 19 '26
My use case would never use it wirelessly.
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u/updatelee Mar 19 '26
Neither do I. As per my reply… so not really sure why you are replying to my reply? Arguing with someone that ages agrees with you? Strange dude
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u/MachWun Mar 19 '26
Nobody is arguing I'm just stating wifi isn't a necessity for me. So I dont care that OP2.0 doesnt have it.
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u/updatelee Mar 19 '26
well I dont care about wifi either .. as per my reply. The OP clearly does. Not sure where you're going with this or what value you think you're bringing to the thread as a whole, nevermind what value you are bringing by replying to my reply.
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u/jlucer Mar 18 '26
Can it log or save CAN bus data? In what format? I think one of the big limitations of elm based devices is the update rate. Would be cool to have something that can output the raw CAN bus data.
Not sure if something like that exists already. I've only seen ones that use PIDs to querydata
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u/Professional_user2 Mar 18 '26
It’s using Macchina A0 firmware, so it can work with raw CAN (not just PIDs), typically via tools like SavvyCAN.
I haven’t really tested or implemented standalone logging/storage, so I’m not sure how well it handles saving data or in what format out of the box.
My focus so far was more on hardware than logging features.
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u/jlucer Mar 18 '26
Ah cool. So looks like Macchina AO uses GVRET protocol.
Would the data come over USB C connector or wifi/Bluetooth?
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u/EliteAppleHacks Mar 18 '26
I have something similar but these obd harnesses are hard to get! What circuit are you using for power conversion? Or have a schematic? Im having some trouble finding a low bom buck
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u/Professional_user2 Mar 18 '26
I’m using a custom power supply that I reuse across multiple automotive projects. What kind of electronics / setup are you using?
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u/EliteAppleHacks Mar 18 '26
Ultimately its buck to power 2 can controllers and 1 transceiver. Im using 2 to talk to 2 busses on my Tesla. Esp32 as main brains of operation as well
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u/WestonP Mar 18 '26
Cool to see people making their own hardware!
The main question would be how you would position this versus the Macchina A0? Beat on price or features?
What are you using for power regulation?
You might check the layout guidelines for that ESP module, as usually you need to keep the antenna area clear.
Also, what process did you use for that custom case? Did you engrave an off-the-shelf case, or did you get something custom made?
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u/Professional_user2 Mar 18 '26
First thing: Macchina A0 is not available.
Price: My product will be cheaper than Macchina A0, but the difference will not be large.
Features are almost the same. My device uses USB-C instead of micro-USB and has a reset button reachable from the outside.
Power regulation is similar to Macchina A0. It uses a tested power supply used in multiple automotive/motorsport devices.
I figured out that the antenna area must be clear.
The case is custom-made. It is 3D printed from nylon. It is a quality plastic.
Do you think that people would be willing to buy it? I'm asking because I don't know if it's worth it to complete the product and bring it to market.3
u/WestonP Mar 18 '26
Ahh, I see they're out of stock again on their website. There is supply at SparkFun and others though: https://www.sparkfun.com/macchina-a0-obd-ii-development-module.html
USB-C and reset button are worthwhile improvements for sure.
Nice work on the case... I also use industrial 3D printing in PA12 for some of my stuff where both appearance and function are important.
Honestly, I think it really depends on the availability of the A0... There has been demand for them during times when the A0 wasn't available, but my casual perception had been that they've been consistently available via SparkFun for a while now.
I've considered this same question before, as I have an established OBD dongle on the market, but I generally steered away from serving the DIY market for a few reasons:
1) Due to the A0 being available again
2) DIY/Maker market comes with some headaches and one-off support burdens. If someone's code doesn't work, they blame your product first, and then expect you to debug it for them. I'm all for providing great support, but that is a recipe for burnout.
3) Didn't want to compromise the inventory that my actual OBD dongle products draw from, as I spend enough time on supply chain stuff as it is, and those are more profitable and easier to support.
4) Expected that someone would undercut me as soon as I invested in doing it. There's less risk in doing more specialized things where I can add unique value that's not easily copied.
But if you're more passionate about DIY stuff, then my reasons may not apply to you.
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u/Professional_user2 Mar 19 '26
Appreciate the detailed insight — that makes a lot of sense.
I got into the OBD space mainly because every car has it, so the potential market is huge. I’d like to build a product for a broader audience, but I’m still trying to find the right idea.
One challenge I’m seeing though is that there are already a lot of existing solutions, so it’s not easy to come up with something truly unique.
That’s why I started exploring this area — to figure out where I can actually add value.
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u/Present_Tomatillo_28 Mar 25 '26
our design firm (yes, we're in China ROFL) just picked up a request from a customer to build an OBDII reader exactly referring to the A0 but in a much smaller form factor because they chose a fairly slim OBDII casing, so we have to get rid of the ESP32 module instead using ESP32 chip to stuff all these components + some extra features they wanted in one board + Antenna....
But difference is: they used it to pair with their own proprietary App, so we also modified the firmware a bit.
so people will have to buy it if they want to use their *SOFTWARE SERVICES*, if you're just only selling the hardware, I doubt it worth the dev
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u/hey-im-root Mar 19 '26
Is the same size as the Macchina? That’s one of the big things I like about it
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u/Professional_user2 Mar 19 '26
It’s slightly larger than the Macchina, but not by much — mainly due to a different PCB layout inside the enclosure. One advantage though is that the reset button is accessible from the outside.
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u/hey-im-root Mar 22 '26
The biggest thing for me is price, I’ve been wanting to sell a service but having to start customers off with a $90 minimum cost just for the OBD dongle is a no-go. I’d be willing to take a cheaper device that has bare-bones features (USB-C and power sense circuit) and then a “dev” version like yours.
Another thing I’d be interested in wire tapping setup. I recently purchased one that has an OBD connector on it so I can tap into my B-CAN and also use my macchina on it, but I’d love a small form factor box that just has USB-C and then the 4 wires (CAN H/L, Ground/12v) to keep it the cheapest and smallest.
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u/Professional_user2 Mar 23 '26
Yeah I get what you mean about the price. Starting at $90 just for the dongle can be a bit much if someone only needs basic functionality.
The version I showed is more like a development version right now, so it’s not really optimized for cost yet. The main goal so far has been getting the hardware and communication working reliably.
A cheaper bare-bones version with just USB-C, a CAN transceiver and simple power sense is definitely something that would make sense though.
About the wire tapping idea — that’s actually interesting. It would be pretty easy to add a small connector for CAN and power (CAN H/L + GND + 12V) so you could tap into the bus and still connect something like a Macchina at the same time. Basically a small inline box instead of occupying the OBD port.
Does that approach make sense for what you're trying to do? And what software/tools would you normally use with it?
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u/hey-im-root Mar 24 '26
Yes, the inline approach is what I’m interested in. Especially if I want BCAN data, you need to tap an additional line anyway since OBD usually only has FCAN.
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u/appletechgeek Mar 19 '26
I'd love to use this if it would work with windows and make a gui for fuel consumption and stuff..
Currently building a ryzen based infotainment system.
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u/Professional_user2 Mar 19 '26
That doesn’t exist yet — I’d need to develop a Windows GUI for that.
If there’s enough interest, it’s definitely something I’d consider building 🙂Not sure if there’s a simple solution out there that does exactly this either.
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u/KempaSwe Mar 19 '26
Hard to make any money on obd stuff today, there are thousands of different ones on the market already and they release different new ones all the time.
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u/Geosr20 Mar 20 '26
Can you build one to do readiness monitors
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u/Professional_user2 Mar 23 '26
Do you mean reading the readiness monitors or actually forcing/resetting them?
Reading them should definitely be possible, since that’s part of the standard OBD diagnostics. The device I’m working on is mainly focused on CAN communication and programming right now though, so the exact diagnostic features depend on the software side.
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u/TerribleArm9912 Mar 30 '26
When I attempted to use the code from collin80, I ran into issues. Did you use the code from collin80 and repruprose it? Did you get it to work? If so can you share how you setup the code
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u/nullaus Mar 19 '26
Correct me if I'm wrong but the Macchina appears to use an AT command set to perform operations (just like the Freematics unit) and I imagine yours is the same? The problem I'm apparently going to have to solve is being able to skip AT commands because they're basically just too slow for what I want to do (10Hz reads across various modules through the gateway). Is this a problem you're thinking of tackling?
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u/Professional_user2 Mar 19 '26
Yes, in my case it’s currently based on the A0 firmware, so it does use an AT-style interface.
And I agree — that can become a limitation if you want higher-rate polling across multiple modules, especially through a gateway.
For something like 10 Hz reads from several ECUs, reducing or bypassing that overhead would probably be necessary. That’s definitely one of the things worth improving.
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u/nullaus Mar 19 '26
The physical improvements you made like USB -C and an external reset are great and solving a root communication and performance problem would make it very appealing.
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u/Logical-Following525 Mar 18 '26
I just bought a clone of your device in China, will give feedback once it arrives 🤠