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Saturday, March 2, 2024

OBD-II scanner teardown

What’s an OBD-II (generally alternatively known as OBD-2, and different occasions in both type absent the interstitial hyphen) scanner? Answering that query first requires an understanding of what OBD is. The acronym stands for on-board diagnostics; right here’s the introductory abstract from Wikipedia’s entry:

On-board diagnostics (OBD) is a time period referring to a car’s self-diagnostic and reporting functionality. OBD programs give the car proprietor or restore technician entry to the standing of the varied car sub-systems. The quantity of diagnostic data obtainable through OBD has various broadly since its introduction within the early Nineteen Eighties variations of on-board car computer systems. Early variations of OBD would merely illuminate a malfunction indicator mild (MIL) or “fool mild” if an issue was detected, however wouldn’t present any data as to the character of the issue. Trendy OBD implementations use a standardized digital communications port to supply real-time knowledge along with a standardized sequence of diagnostic hassle codes, or DTCs, which permit an individual to quickly determine and treatment malfunctions throughout the car.

Apparently, I realized whereas researching this piece, the time period “OBD-I” was retroactively utilized to an earlier California Air Sources Board (CARB)-initiated on-board diagnostics method, after the standardization and rollout of OBD-II roughly a decade later. OBD-I first:

The regulatory intent of OBD-I used to be to encourage auto producers to design dependable emission management programs that stay efficient for the car’s “helpful life”. The hope was that by forcing annual emissions testing for California beginning in 1988, and denying registration to autos that didn’t move, drivers would have a tendency to buy autos that might extra reliably move the check. OBD-I used to be largely unsuccessful, because the technique of reporting emissions-specific diagnostic data was not standardized. Technical difficulties with acquiring standardized and dependable emissions data from all autos led to an incapability to implement the annual testing program successfully.

Now for OBD-II, which was necessary for all automobiles bought in the USA starting in 1996, once more quoting straight from Wikipedia:

OBD-II is an enchancment over OBD-I in each functionality and standardization. The OBD-II customary specifies the kind of diagnostic connector and its pinout, {the electrical} signaling protocols obtainable, and the messaging format. It additionally gives a candidate listing of car parameters to observe together with tips on how to encode the information for every. There’s a pin within the connector that gives energy for the scan device from the car battery, which eliminates the necessity to join a scan device to an influence supply individually. Nevertheless, some technicians may nonetheless join the scan device to an auxiliary energy supply to guard knowledge within the uncommon occasion {that a} car experiences a lack of electrical energy as a result of a malfunction. Lastly, the OBD-II customary gives an extensible listing of DTCs. On account of this standardization, a single machine can question the on-board laptop(s) in any car.

Wikipedia’s complete on-board diagnostics entry, which additionally covers a Common Motors-proprietary diagnostics scheme known as Meeting Line Diagnostic Hyperlink (ALDL) together with numerous OBD-II successors, is effectively value a learn. And in case you’re not conscious of what the connector is that’s referred to earlier, right here’s a pic:

Again within the non-standardized OBD days, diagnostics connectors weren’t solely applied in numerous shapes, sizes, and pinouts, they had been additionally scattered in numerous places across the car, together with below the hood. These days they’re required to be inside 2 ft of the steering wheel; most frequently they’re discovered beneath the dashboard.

One key advantage of such standardization (which, by the way in which, curiously does NOT lengthen to a typical sign protocol in all implementations; 5 choices are supported. Extra on that in a bit…) is that producers can develop knowledge “readers” not just for restore store use but in addition for common car proprietor utilization, at minimal so shoppers can get some concept of the car’s standing and, in the event that they’re “wrenches”, also can deal with any crucial work themselves. That stated, kind “OBD-II” into the Amazon web site search bar and also you’ll be introduced with a prolonged and in any other case bewildering listing of outcomes spanning a number of pages, for diagnostics scanners ranging in worth from lower than $10 to a number of hundred {dollars}. A listing of their variations (albeit off the highest of my head, subsequently doubtless not complete) encompasses components corresponding to:

  • How well-known (or not) the gear provider’s “model” is.
  • The breadth of autos (each producer, mannequin, and mannequin years) supported.
  • If the scanner firmware is recurrently up to date each to squash bugs and help new autos, and if that’s the case, how (through USB connection to a pc, Bluetooth obtain from a cellular machine, direct Wi-Fi obtain, and so on.) and the way usually updates are made obtainable.
  • If the scanner is solely a diagnostic knowledge reader or if it additionally helps knowledge reset or much more elaborate specific-data configuration programming.
  • Which car system(s) are supported, and to what diploma in every case: engine, transmission, brakes, steering, charging, and extra basic electrical, and so on.
  • Person enter schemes: buttons, touchscreen, and so on.
  • Information output schemes: LEDs, an LCD show, help for knowledge add to a related laptop, smartphone, pill, and so on.
  • Connectivity between the male OBD-II connector (and its related circuitry) and the principle reader: wired, Bluetooth, and so on. Some Bluetooth-based models, in truth, provide enough in-connector “smarts” that the rest of the reader consists solely of software program operating on a wirelessly tethered laptop or cellular machine!

The OBD-II scanner that I at present personal (for causes that I’ll save for one more weblog put up one other day) is an Autel AutoLink AL519, which I purchased final November from an eBay retailer for $59.98:

I’ve lengthy puzzled what its (and comparable merchandise’) insides seemed like. To fulfill my curiosity through this teardown venture, I went with a extra modestly priced (albeit nonetheless mainstream-featured) machine, the THINKOBD 100 from THINKCAR Tech, which set me again solely $14.94 (on sale) from Amazon after I purchased it in January. Right here’s a inventory picture:

And a promo video:

I’ll as regular start the dissection with a sequence of outer packaging pictures:

The THINKOBD 100 is self-powered by the availability voltage (and present) and floor feeds originating on the feminine OBD-II port it’s related to, which is fairly slick:

I like the brutally sincere, albeit grammatically and in any other case considerably convoluted, wording on the bottom:

What’s Cheaper than It isn’t a Good as It, what’s Higher than It isn’t as Low-cost as It

Though THINKCAR TECH is US-based, the THINKOBD 100 is China-manufactured; I’m guessing that imperfect translation to English is on the root of the clumsy wording. In an analogous vein, I discover it curious that as additionally famous on the bottom, the included person guides present directions in seven completely different languages…none of them Chinese language. Notice, too, that the high-quality print signifies that the unit helps all 5 of the aforementioned OBD-II sign protocol choices.

Onward to the remaining (and relatively boring) field sides:

And now, let’s crack open the field’s high flap:

That’s a reassuring sticker!

Right here’s what’s inside, as regular accompanied by a 0.75″ (19.1 mm) diameter U.S. penny for measurement comparability functions.

The THINKOBD 100, not together with its completely related cable, has dimensions of 4.72 x 2.55 x 0.79 inches, and the assemblage weighs 8 ounces. Notice, too, the twin person guides; one has three languages’ value of directions, the opposite 4. Listed below are the 2 panels’ value of English-language tutorial prose:

The included (a pleasant contact!) USB cable is used to obtain and set up up to date software program to the machine. It’s predictably USB-A on one finish, however archaic mini-USB on the opposite…apparently this product has been obtainable on the market for some time.

Right here’s the male OBD-II connector on the finish of the three.2 ft completely hooked up cable:

And right here’s what’s left as soon as the scanner and USB cable are faraway from their white plastic packaging environment:

Now for our affected person. That’s a 1.77 in. (diagonal) 160×128 pixel coloration TFT LCD on the entrance:

At backside is the mini-USB connector for updates, together with an information-filled sticker:

The perimeters are pretty bland, though I’ll word that the textured case is simple to grip:

At high is the different finish of the cable that connects to the OBD-II port:

And at last, on the again we see the 4 screws that time to our pathway inside:

what comes subsequent, proper?

The PCB pops proper out of the remaining half of the case:

Let’s look first on the comparatively unexciting PCB entrance aspect:

Now for the again aspect, containing the majority of the circuitry:

Right here’s a closeup of the comparatively circuitry-cluttered high half:

On the very high, clearly, is the connector that the OBD-II cable plugs into, with indicators subsequently routing between there and the PCB. Under and to the left of it are two 2903 low-power dual-voltage comparators (producer unknown; does anybody know what firm that vertical-line emblem is related to? The second mark line says “AK2SF” if that helps).

Instantly under the connector is an fascinating chip, the SIT1044T, from an organization known as Silicon Web of Issues Know-how. It’s a 5 Mbps high-speed CAN (controller space community) FD (versatile knowledge charge) transceiver; I’m certain that at the least a few of you already additionally seen the related “CANL” and “CANH” markings on the PCB close to the connector, proper? To its proper is the AMS1117, a linear regulator from Superior Monolithic Methods. And to the fitting of that is one other regulator, the 78M05 (producer unknown).

The most important (and highest pin depend) IC on the board is the system “brains”, the MM32F103RBT from one other Chinese language semiconductor firm, MindMotion. It’s a 96 MHz Arm Cortex-M3 based mostly SoC additionally containing (amongst different issues) 128 KBytes of flash reminiscence and 20 KBytes of SRAM. And talking of flash reminiscence, under the applying processor is extra of it, 64 Mbits of SPI NOR flash reminiscence to be actual, within the chip with markings figuring out it as GigaDevice Semiconductor’s GD25Q64E. No, I don’t know what these blue and inexperienced scribbles on the latter two ICs imply, both, though they had been presumably added by whoever assembled after which examined the PCB containing them!

In spite of everything that upper-half pleasure, the corresponding decrease half of the bottom of the PCB is boring as compared, that’s until you’re into diodes and different passives…

At this level I’ll cease disassembling, as a result of as common readers of my teardowns already know, I all the time desire to go away my “sufferers” in a situation the place I can later reassemble them to a completely purposeful state for both my or a charity donation recipient’s subsequent use. That stated, I’ll preserve the OBD-II scanner in items till after this text is revealed, so I can reply any “what’s that” or different questions you may need. Pontificate within the feedback! And keep tuned for that “why is OBD-II personally related to me” story to observe sooner-or-later.

Brian Dipert is the Editor-in-Chief of the Edge AI and Imaginative and prescient Alliance, and a Senior Analyst at BDTI and Editor-in-Chief of InsideDSP, the corporate’s on-line publication.

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