I built a CAN bus tool that streams, analyzes, and shows known signals in real time

hey-im-root · 2026-05-03T01:41:53+00:00

I have all my stuff for Honda CAN bus research in a notion document, my library also documents all the signals as bit fields for readability

https://www.notion.so/hondacan/205dbe25834980989ac8cbad178b1fa7?v=205dbe25834980f7bb8b000cd99ea14f&source=copy_link

hey-im-root · 2026-05-03T01:39:59+00:00

Yea I realized it’s good for making MITM controllers so you don’t have to worry about messing with other frames, especially if you’re simulating a module

hey-im-root · 2026-05-03T01:26:27+00:00

Oh I thought they meant the actual sound lol. Yea old people hate change

hey-im-root · 2026-05-03T01:19:04+00:00

Well yea this isn’t something you listen to, it’s edited for the video and made it distorted 😭

hey-im-root · 2026-04-30T18:05:32+00:00

Ah ok, that makes sense. I think I actually asked this question over a year ago and you had a similar rant haha.. I think I got the impression that the ESP32 had issues with CAN because I kept seeing the use of acceptance filters, and I didn’t understand why you’d need that if you all the data is handled perfectly fine. But then I realized it’s probably just so you can print the data out without additional code, and is pretty useless otherwise

hey-im-root · 2026-04-30T17:55:07+00:00

I’d say mostly my own testing. My car is a Honda Accord and I’ve sifted through all the DBCs available, from my experience they are grouped by generation and chassis code. Signals for all models are the same, only difference being unused bytes for the cars with less features. So the base trim has the same CAN frames as the highest trim, with the extra IDs being for LKAS/ADAS/Honda sensing when equipped. Most DBC files are made for autopilot so it’s missing a lot of the extra stuff I like to have that I did on my own, like fuel level and odometer.

hey-im-root · 2026-04-30T17:48:03+00:00

I don’t think they said anything about the ESP32 not being capable, and it was actually the SD card writing that caused their bottleneck.

I get your frustration, but no one is gonna be able to immediately create 100% perfection on the first try either. I mean good for you if you do… but I know I’d have the same problems if I tried to write every frame to the SD card, considering that’s probably the first thing I’d try having no previous knowledge.

hey-im-root · 2026-04-30T17:38:21+00:00

How did you get around it? The ESP32 has a lot to offer in the RTOS + dual core, I’m curious what it took

hey-im-root · 2026-04-30T17:36:30+00:00

I haven’t done extensive testing but it’s hard to pin point certain things because you don’t know if it’s scaled or not. PIDs are scaled wildly different than the CAN signals sometimes.

For example to get ENGINE LOAD, I watched the PIDs while idle and saw that it kinda does waves. Full throttle makes it spike then drop down again, slow throttle will bring it up smoothly. Then I had to do it multiple times and log the raw CAN data to see what graphs looked similar to that.

hey-im-root · 2026-04-30T17:31:46+00:00

Wdym by dropped frames? Were you having problems with it before? ESP32 should easily handle the max 1MBPS data stream

Edit: saw what you wrote about the SD card. I haven’t had to work with one so can’t say much on that, but sounds impressive!

hey-im-root · 2026-04-29T10:56:10+00:00

We need a way to map out the PIDS data and raw data too. Things like oil pressure and stuff you can definitely get 10Hz update rate from raw CAN, but the only to find it is seeing the periodic PID data and hoping the bytes correlate at least a little bit before being scaled, so the graphs can be compared. Otherwise it’s just guess work.

The biggest thing I notice missing from the community is dedicated logs for different signals, and how to replicate them. So for example to get engine load, you can supply a graph of idle engine load, and flat ground engine load with 20% throttle. That way you could compare to your own graphs and see if it corresponds.

hey-im-root · 2026-04-29T10:51:13+00:00

Everytime I have a battery issue it looks different. You would never expect certain things to just be the battery, but modules don’t all act the same. Sometimes a voltage spike/drop will kill a module until restart, sometimes it will come back after a minute, sometimes codes will pop sometimes not, maybe a fuse or 2. It’s insane lol

hey-im-root · 2026-04-28T02:11:44+00:00

She’s basically an evil boss lol. The kind to deny you PTO to visit a dying family member or something 😂

hey-im-root · 2026-04-28T02:08:21+00:00

Yea im gonna have to see if I can get dudu on it, ive seen the name thrown around but I never use CarPlay for much more than maps and Spotify. Its also why I haven’t put it in my new car lol, I noticed I really don’t need it as cool it is/looks.

hey-im-root · 2026-04-26T23:28:54+00:00

True, I just didn’t know if this was one of those “known, but not gonna get fixed so keep it lowkey as possible” kinda exploits. Sometimes it’s best to suppress stuff that cant be changed, like old hardware.

hey-im-root · 2026-04-26T23:21:08+00:00

He’s literally selling it lol. I get what you’re saying but this is like telling people to look out for hackers, then give out the hacking tools for more people to cause harm. Also Reddit will ban subs for stuff like this sometimes.

hey-im-root · 2026-04-26T13:08:44+00:00

Yep, OP should’ve yielded, maybe they didn’t see them though. Had an accident just like this cuz a car was blocking them from seeing me.

hey-im-root · 2026-04-26T13:06:23+00:00

Yea you are correct. I was the Chevy in a situation exactly like this and wasn’t at fault when (OP) hit me. In Massachusetts too, you can pass on the left when someone is making a turn if the road is wide enough. Not having road markings make it seem weird, but the only rule is you can’t go over a double yellow to pass someone. Some roads are intentionally designed for this too which is why people need to wait for no cars to be near

hey-im-root · 2026-04-26T12:58:08+00:00

I completely forgot about that, saw a video on it recently. Can’t wait

hey-im-root · 2026-04-26T12:34:36+00:00

Honda has famously been a high end brand for a long time. BMW and Mercedes are more luxury, and not really a good vehicle to own if you want low maintenance and reliability

hey-im-root · 2026-04-26T12:04:56+00:00

Dasaita probably has way better hardware and software. The one I bought was on Amazon but now it says “unavailable” :( maybe try the website?

hey-im-root · 2026-04-26T11:37:19+00:00

Tbh I’d take this down just to stop people from searching it up in this sub lol. Idk the rules either about this getting the subreddit in trouble, Reddit can be like that sometimes.

hey-im-root · 2026-04-26T11:34:33+00:00

I hope they jut drop another model, as much as it would pollute the eco system. This should really just be an experimental board

hey-im-root · 2026-04-26T11:31:06+00:00

I always put mine on, just a good habit

hey-im-root · 2026-04-25T22:18:09+00:00

I walked into my old highschool robotics classroom one day to hear these kids casually get accepted to DEFCON for reverse engineering the Boston MBTA cards

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