As part of our commitment to ensuring broad compatibility across vehicle platforms, we’ve been diligently developing the OBD-II classic adapter. This update details the progress on this essential piece of hardware and explains how it functions to bring older vehicles into the modern OBD-II landscape, particularly for users of systems like our RaceCapture and the RaceCapture units recently funded through Kickstarter Obd2 campaign.
How It Works
The OBD-II classic adapter, internally codenamed OBD2CAN, serves as a crucial bridge for car owners with older OBD-II protocol vehicles. It effectively translates these legacy protocols into the modern CAN bus OBD-II standard. Think of it as a translator, allowing newer, CAN bus-centric devices to communicate with older cars. It’s important to set expectations – while this adapter ensures compatibility, it’s not a magic wand. It won’t boost the speed of older OBD-II protocols, nor will it unlock access to additional data channels beyond what the original OBD-II system provides. So, if you’re driving an older BMW E36 known for its less-than-stellar OBD-II performance, this adapter will enable CAN bus communication, but the inherent limitations of the original OBD-II system will remain.
Why This Kickstarter OBD2 Adapter Matters
You might wonder, why create such an adapter? The answer lies in the evolving landscape of OBD-II compatible hardware. Many modern devices, including our own RaceCapture/Pro and the new RaceCapture system that was successfully funded on Kickstarter OBD2, are designed to support only CAN bus OBD-II. CAN bus is a streamlined, efficient standard, and since 2008, virtually all cars (with some models adopting it as early as 2004) utilize CAN. By focusing on CAN OBD-II in our core products, we simplify development and ensure optimal performance for the vast majority of modern vehicles.
However, we recognize the need to support older vehicles. The OBD2CAN adapter elegantly solves this by acting as a transparent bridge. It allows CAN-only systems to seamlessly interface with older cars, eliminating the need for native support of every legacy OBD-II protocol within each device. Directly incorporating all older OBD-II protocols would significantly increase product complexity and cost, impacting testing, manufacturing, and ultimately, the price for features that are becoming less relevant as older car models are phased out. Therefore, an external bridge like our Kickstarter OBD2 adapter offers the most practical and cost-effective solution for installations requiring legacy OBD-II support.
Diving into the Technical Details
At the heart of the OBD2CAN bridge is the robust and proven STN1110 protocol chip and its reference design. This chip handles the heavy lifting of interfacing with all legislated legacy OBD-II protocols, including:
- ISO 14230-4 (Keyword Protocol 2000)
- ISO 9141-2 (Asian, European, and Chrysler vehicles)
- SAE J1850 VPW (GM vehicles)
- SAE J1850 PWM (Ford vehicles)
Utilizing the STN1110 is a significant time-saver, leveraging extensive prior work in managing the intricacies and variations of older OBD-II protocols.
On the CAN bus side, we employ the efficient STM32F072 microcontroller. This acts as the CAN interface and translator to the STN1110’s ELM327-compatible protocol. The operational logic is intentionally straightforward: the adapter receives a PID (Parameter ID) request via CAN, forwards it to the STN1110, receives the PID data back from the STN1110, and then transmits the response onto the CAN bus. From the perspective of downstream systems like RaceCapture, they are simply communicating with a CAN-enabled OBD-II vehicle.
Powering Up: Power Supply Testing
To ensure compatibility across all legacy OBD-II protocols, the OBD2CAN bridge necessitates multiple internal power supplies: 5.7V, 7.4V, 5V, and 3.3V. Assembling this power section involves considerable manual soldering and delicate work with tweezers – a stark reminder of the efficiency of automated pick and place machines in our usual production processes. We’re pleased to report that our initial test unit successfully passed the “smoke test” during power-up!
Completing the Component Assembly
The remaining components on the board are dedicated to supporting the legacy OBD-II protocols (the STN1110 and associated parts) and the STM32 for the CAN bus interface.
The next step involves soldering the male OBD-II plug and the downstream RJ45 connector onto the board.
This bottom-mounted connector design is somewhat unusual for us, dictated by the tight confines of the enclosure we’ve chosen for this adapter.
Enclosure Fitment and Integration
The enclosure requires milling to accommodate the end connector. In the interim, we’re carefully hand-nibbling it to achieve the necessary clearance.
[](Enclosure test fit for the OBD2CAN Classic Adapter)
The result is quite satisfactory, although some minor adjustments to the PCB fitment are still needed to ease the tightness.
Seamless Integration with RaceCapture Systems
Here’s a glimpse of the adapter seamlessly integrated with a RaceCapture/Pro MK2 system, demonstrating its in-line connectivity. The integration principle is identical with the new plug-and-play RaceCapture units from our Kickstarter OBD2 campaign!
What’s Next?
Our immediate next step is firmware development to bridge the communication gap between the two OBD-II worlds and ensure seamless operation with our OBD-II protocol simulator. For initial bench testing and firmware development, the ECUSIM 5100 provides a convenient and efficient alternative to testing with a range of older vehicles, and it certainly occupies less space on the workbench.
