IPhone OBD-II App

September 27, 2008 by 61 Comments

Rev by DevToaster is an application for the iPhone and iPod Touch that allows real-time monitoring of vehicle ECU data from the OBD-II port. Rev interfaces with a WiFi OBD-II dongle.

If your check engine light is on or flashing, REV is able to check the engine code, list all of the engine codes stored in the vehicle, and reset the stored codes or check engine light.

Rev is able to monitor real-time; vehicle speed, RPM, fuel consumption, engine coolant temp, fuel pressure, calculated engine load, throttle position, intake manifold pressure, air intake temp, timing advance, mass air flow, fuel level, barometric pressure, EVAP system vapor pressure, and fuel trim.

A brief video of REV in action is after the break.

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Connecting Your Car To Home Assistant

June 4, 2026 by 28 Comments

With how much time many of us spend in our cars, it makes perfect sense to consider them a second home. Yet even if that’s not the case, there are still good reasons to connect a car to one’s smart home solution like Home Assistant, such as to keep track of certain parameters for easy monitoring and reminders. This is what [The Stock Pot] channel recently demonstrated using a widget that connects to the OBD-II port inside the car, as not every car comes with its own app yet.

The used dongle is the ESP32-S3-based WiCAN from Australian company MeatPi. This device runs the open source WiCAN firmware. After plugging the dongle into the OBD-II port of the car, the device powers on and can be configured via Wi-Fi like any other smart device these days. After that it’s just another Wi-Fi device on the network.

Since each car’s ECU will represent data differently, you need a car-specific configuration, which can take some tweaking. The idea of integrating with Home Assistant is directly supported by MeatPi, with a handy documentation page. Of course [The Stock Pot] shared their configuration if you want to feel inspired. Among the parameters monitored you get things like fuel level, days to service and coolant temperature.

Although you could make the argument that it mostly saves you from having to waddle over to the car to check the data there, being able to remotely access the OBD-II port of a car does seem rather practical even outside of home automation concepts, such as gathering performance statistics and early failure warnings, especially for aspects like tire pressure and unhappy engine or BEV battery conditions that can quickly go from an inconvenience to very expensive.

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Hackaday Links: September 7, 2025

September 7, 2025 by 7 Comments

Two weeks ago, it was holographic cops. This week, it’s humanoid robot doctors. Or is it? We’re pretty sure it’s not, as MediBot, supposedly a $10,000 medical robot from Tesla, appears to be completely made up. Aside from the one story we came across, we can’t find any other references to it, which we think would make quite a splash in the media if it were legit. The article also has a notable lack of links and no quotes at all, even the kind that reporters obviously pull from press releases to make it seem like they actually interviewed someone.

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Supercon 2024: Yes, You Can Use The Controller Area Network Outside Of Cars

March 27, 2025 by 21 Comments

Ah, the CAN bus. It’s become a communication standard in the automotive world, found in a huge swathe of cars built from the mid-1990s onwards. You’ll also find it in aircraft, ships, and the vast majority of modern tractors and associated farm machines, too.

As far as [Randy Glenn] is concerned, though, the CAN bus doesn’t have to be limited to these contexts. It can be useful far beyond its traditional applications with just about any hardware platform you care to use! He came down to tell us all about it at the 2024 Hackaday Supercon.

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Train Speed Signaling Adapted For Car

September 11, 2024 by 33 Comments

One major flaw of designing societies around cars is the sheer amount of signage that drivers are expected to recognize, read, and react to. It’s a highly complex system that requires constant vigilance to a relatively boring task with high stakes, which is not something humans are particularly well adapted for. Modern GPS equipment can solve a few of these attention problems, with some able to at least show the current speed limit and perhaps an ongoing information feed of the current driving conditions., Trains, on the other hand, solved a lot of these problems long ago. [Philo] and [Tris], two train aficionados, were recently able to get an old speed indicator from a train and get it working in a similar way in their own car.

The speed indicator itself came from a train on the Red Line of the T, Boston’s subway system run by the Massachusetts Bay Transportation Authority (MBTA). Trains have a few unique ways of making sure they go the correct speed for whatever track they’re on as well as avoid colliding with other trains, and this speed indicator is part of that system. [Philo] and [Tris] found out through some reverse engineering that most of the parts were off-the-shelf components, and were able to repair a few things as well as eventually power everything up. With the help of an Arduino, an I/O expander, and some transistors to handle the 28V requirement for the speed indicator, the pair set off in their car to do some real-world testing.

This did take a few tries to get right, as there were some issues with the power supply as well as some bugs to work out in order to interface with the vehicle’s OBD-II port. They also tried to use GPS for approximating speed as well, and after a few runs around Boston they were successful in getting this speed indicator working as a speedometer for their car. It’s an impressive bit of reverse engineering as well as interfacing newer technology with old. For some other bits of train technology reproduced in the modern world you might also want to look at this recreation of a train whistle.

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ESP32 Used As Wireless CAN Bus Reader

November 22, 2023 by 35 Comments

The CAN bus, accessible through the OBD-II port, is the channel that holds all the secrets of the modern automobile. If you want to display those for your own perusal, you might consider this nifty tool from [EQMOD].

Yes, it’s an OBD-II dongle that you can build using an ESP32 WROVER module. It’s designed to read a car’s CAN bus communications and display them on a self-hosted web page, accessible over WiFi. The build relies on the dual-core nature of the ESP32, with the first core handling CAN bus duties via the SN65HVD230 CAN bus transceiver chip. The second core is responsible for hosting the web page. Data received via the CAN bus is pushed to the web user interface roughly every 60 to 100 milliseconds or so for information like RPM and speed. Less time-critical data, like temperatures and voltages, are updated every second.

It’s a neat little thing, and unlike a lot of dongles you might buy online, you don’t need to install some dodgy phone app to use it. You can just look at the ESP32’s web page for the data you seek. The graphics may be a little garish, but they do the job of telling you what’s going on inside your car. Plus, you can always update them yourself.

Getting to grips with the CAN bus is key if you want to diagnose or modify modern vehicles. Meanwhile, if you’ve been cooking up your own electronic vehicular hacks, don’t hesitate to drop us a line!

PyOBD Gets Python3 Upgrades

September 17, 2023 by 19 Comments

One of the best things about open source software is that, instead of being lost to the ravages of time like older proprietary software, anyone can dust off an old open source program and bring it up to the modern era. PyOBD, a python tool for interfacing with the OBD system in modern vehicles, was in just such a state with its latest version still being written in Python 2 which hasn’t had support in over three years. [barracuda-fsh] rewrote the entire program for Python 3 and included a few other upgrades to it as well.

Key feature updates with this version besides being completely rewritten in Python 3 include enhanced support for OBD-II commands as well as automating the detection of the vehicle’s computer capabilities. This makes the program much more plug-and-play than it would have been in the past. PyOBD now also includes the python-OBD library for handling the actual communication with the vehicle, while PyOBD provides the GUI for configuring and visualizing the data given to it from the vehicle. An ELM327 adapter is required.

With options for Mac, Windows, or Linux, most users will be able to make use of this software package provided they have the necessary ELM327 adapter to connect to their vehicle. OBD is a great tool as passenger vehicles become increasingly computer-driven as well, but there are some concerns surrounding privacy and security in some of the latest and proposed versions of the standard.