If you’ve ever tinkered with older GM vehicles (roughly mid-1990s to early 2000s), you might have encountered the term "Class 2" communication or J1850 VPW. This was General Motors’ protocol for in-vehicle networking before the CAN bus took over popularity. For hobbyists working on diagnostics, instrument clusters, or engine swaps, understanding J1850 VPW can be incredibly useful.

What is J1850 VPW?

J1850 is an SAE standard for automotive communication, and GM used VPW (Variable Pulse Width) as the modulation method. Unlike PWM (Pulse Width Modulation, used by Ford in J1850), this protocol is single-wire. J1850 PWM is a differential pair. GM called its implementation "Class 2", which ran at 10.4 kbps—slow by today’s standards but sufficient for its time. Most systems also supported “4x mode” which was 41.6 kbps. J1850VPW allowed modules like the PCM (Powertrain Control Module), BCM (Body Control Module), and instrument cluster to share data.

How Does VPW Work?

    • Single-Wire Bus: Unlike CAN (which uses two wires), VPW communicates over a single wire, often grey in GM vehicles.
    • Message Structure: Messages include a header, data bytes, and a checksum.
    • Varying pulse widths: '1' bit -HIGH 64uS, '0' bit -HIGH 128uS, Start of Frame - HIGH 200uS

Where Was J1850 VPW Used?

GM implemented Class 2 from the early 90s to the early to mid-2000s. Think like GMT800 (Silverado) or 4th gen Camaro. It was eventually phased out in favor of CAN bus around the mid-2000s. GM used single and 2-wire can once replacing J1850 VPW.

Why Should Hobbyists Care?

If you’re working on an older GM vehicle, understanding VPW helps with:

  • Diagnostics: Use a scan tool that supports VPW (like an older OBD2 reader).
  • Retrofitting: Swapping clusters or modules from VPW-era vehicles.
  • Reverse Engineering: Logging and decoding VPW messages for custom projects.

How to Interface with VPW?

You have a few options to interface with J1850VPW:

  • Commercial off-the-shelf ELM327-based devices can be an easy and tempting solution. The drawback here is varying degrees of quality and documentation. OBDLINK has worked for me in the past.
  • OEM and aftermarket tools are excellent for troubleshooting, but cost is the drawback.
  • OBDX-pro tools are not ELM327s, and he offers a range of them. Great for troubleshooting or programming.
  • My J1850VPW Transceiver. It's suitable for making custom circuits and such. It's not a troubleshooting tool like the one mentioned above. Module Using DLC or J1850VPW-Transceiver

Final Thoughts

While J1850 VPW is outdated, it’s still relevant for classic GM enthusiasts and tinkerers. If you’re diving into automotive hacking, learning VPW is a great way to understand early vehicle networking before moving on to CAN bus. I have a ton of information about it on my YouTube channel, so take some time and check it out if you found this interesting.

Protecting your computer and connected devices is critical in industrial and development environments. Isolated serial communication makes this possible. Industrial-grade isolated USB-to-serial adapters (such as the B&B USOPLT4 ) provide essential electrical separation, ensuring safety, reliability, and data integrity when interfacing with microcontrollers, embedded systems, or industrial automation equipment. This topic is related to one of my latest video's on YouTube. Why does isolation matter so much?

1. Electrical Isolation: Preventing Ground Loops & Voltage Differences

One of the biggest risks in industrial communication is ground loops, a scenario in which two connected devices have different ground potentials, causing unintended current flow. This can lead to erratic behavior, data corruption, or permanent hardware damage.

Example: In high-power applications (e.g., motor controllers or PLCs), the ground reference may differ significantly from your computer's ground. A non-isolated connection could allow excessive current to flow through the USB port, risking damage to both the PC and the device. An isolated USB-to-serial adapter eliminates this risk by breaking the direct electrical path while still allowing data transmission.

2. Protection Against Spikes, Surges, and ESD Events

Industrial environments are prone to voltage transients—power surges, inductive kickback from motors, or electrostatic discharge (ESD). Without isolation, these spikes can travel straight into your computer, frying USB ports or internal circuits.

How isolation helps:

  • Opto-isolators or transformer-based isolation act as a barrier.
  • High-voltage spikes on the device side won't reach your PC, keeping everything safe.

3. Safeguarding Expensive Prototypes & Test Equipment

A single wiring mistake or voltage surge can destroy custom prototypes, industrial controllers, or sensitive test gear. Early-stage prototypes often lack robust protection circuits, making them especially vulnerable.

Why isolation is a must:

  • Shields prototypes from PC-side faults (ground loops, accidental shorts).
  • Prevents damage to your computer from prototype-side failures.
  • Saves time, money, and frustration in R&D and industrial automation.

Conclusion: Don't Risk It Use Isolation!

An isolated serial connection isn't just a luxury. It's a necessity when working with industrial equipment, high-voltage prototypes, or sensitive electronics. By preventing ground loops, voltage spikes, and EMI issues, isolation ensures long-term reliability and safety for your PC and connected devices.

Whether you're in R&D, industrial automation, or field testing, an isolated USB-to-serial adapter a must-have tool. It can save you from costly repairs, downtime, and corrupted data.

A reliable and efficient power supply can make all the difference in soldering. That's why I'm excited to share my latest project, made possible by the generous support of JLCPCB. In this article, we'll delve into how I designed and installed a power supply that seamlessly connects an EGO 56-volt battery to a 24-volt T12 soldering station. Get ready to go portable with your T12-style soldering station.  If you want to make the board or check out the design, it is here: https://oshwlab.com/garnerm91/56v-to-24v-5amp. This project is sponsored by JLCPCB, $2 For Your PCB+PCBA, Register to Get $54 Coupons: https://jlcpcb.com/IYB

The Need for a Power Upgrade

The T12 soldering station is popular among electronics enthusiasts due to its precision and versatility. However, its stock power supply may sometimes need to catch up regarding performance or convenience. Recognizing this opportunity for improvement, I set out to create a solution that would provide a higher voltage input while maintaining the station's functionality.

The flexibility of using a battery-powered solution means you can work in locations where a traditional power outlet may not be easily accessible. Whether working in your workshop or on the go, this power supply lets you take your soldering projects wherever inspiration strikes.

Designing the Power Supply

With the backing of JLCPCB, a leading provider of high-quality PCB fabrication and assembly services, I designed a custom power supply for the T12 soldering station. The goal was to integrate an EGO 56-volt battery, commonly used in outdoor power tools, into the soldering setup.

After carefully planning and prototyping, I finalized a compact power supply module that could efficiently step down the battery's voltage to 24 volts. The design considered power delivery, safety features, and compatibility with the T12 soldering station's existing components.

Installation Process

Installing the power supply inside the T12 soldering station required precision and attention to detail. I documented the step-by-step process in a video on my YouTube channel, where you can follow along and replicate the installation for yourself. The power supply module was designed to fit neatly within the station's housing, ensuring a clean and professional appearance. It installs simply by removing the old power supply and plugging it into the original connector.

Conclusion

Thanks to the support of JLCPCB, I developed and showcased a custom power supply solution for the T12 soldering station. By seamlessly integrating an EGO 56-volt battery, this upgrade offers improved performance, enhanced portability, and expanded possibilities for soldering enthusiasts.

Please watch the YouTube video for a comprehensive guide on installing this power supply in your T12 soldering station. With this upgrade, you can unlock a new level of precision and convenience in your soldering endeavors. Get ready to power up and take your soldering game to new heights!

Check out the full review on YouTube:

The Miniware pocket Logic Analyzer LA104 is a powerful yet affordable tool that packs impressive functionality into a compact package. With four input channels and four programmable output channels, this logic analyzer can capture and analyze a wide range of digital signals, making it an ideal tool for hobbyists, students, and professionals.

One of the standout features of the LA104 is its affordability. While many logic analyzers on the market can be prohibitively expensive, the LA104 provides an accessible option for those without a large budget. Despite its low price point, the LA104 doesn't skimp on features. It offers a range of useful tools and functions that make it a versatile and valuable addition to any electronics toolkit, with custom applications, built-in decoding, and input/output.

The LA104 is easy to set up and operate, with a user-friendly interface that allows you to configure and customize your capture settings quickly. The device is also portable and lightweight, making it easy to take on the go or use in cramped workspaces.

Overall, the Miniware pocket Logic Analyzer LA104 is an excellent choice for anyone needing a budget-friendly logic analyzer that doesn't compromise quality or functionality. With its four input channels and four programmable output channels, it's a versatile tool that can handle a variety of digital signals, and its user-friendly interface makes it easy for beginners and experienced users alike.


Check out the full review on YouTube:

 

For this review, I made a 56-volt to 24-volt buck converter with a 42-volt Undervoltage lockout. It is rated to five amps but will never see over two amps. The main reason for trying out the PCB assembly service was that I did not have time to build this myself, and I was already going to order some of the parts from LCSC, so I figured, why not! If you want to try it out, check out PCBs from $0 https://jlcpcb.com/IYB (Free Setup, Free Stencil, and Coupons!).

The Design Process.

The design process doesn't very much from standard PCB design using EasyEDA PRO. There are two things you will want to keep in mind while designing. First, you will want to ensure the part is in stock with JLCPCB. You will also want to know if the part is a "basic" or an "extended" inventory.  Extended have an extra cost. I wouldn't stress over that extra cost too much on parts you need, but you might want to keep an eye on it for simple parts like resistors.

Ordering.

JLCPCB has made ordering very simple when using EasyEDA Pro. It is as simple as clicking the "order" drop-down and then "order PCB." This will open you into JLCPCB's website, where you can pick your board and assembly options.

 

Video: