Innovation: One calculator to rule them all

Opinions expressed are solely my own and do not represent the views or opinions of my employer or clients.

Background: In a fuel dispenser, the calculator is the electronic subsystem responsible for computing and displaying refueling data, such as the total price, unit price, and fuel volume.

I have always believed that true innovation stems from studying market leaders and their flagship products and going beyond. Twelve years ago, Tokheim was the dominant player in the calculator market, particularly with its groundbreaking graphical calculator featuring a 15o LCD display, which set new industry standards.

Discovery and Disappointment

I embarked on a detailed study of Tokheim's approach and discovered that their system relied on a Windows PC to control the LCDs at both sides of the dispenser, running a proprietary full-screen program. The top two-thirds of the display was reserved for video content, while the bottom third presented the refueling data. The Windows machine was connected to a standard calculator board that managed the fuel dispensing process.

Upon learning how the system worked, I was somewhat disappointed. I’ve never considered Windows a reliable embedded operating system, especially for critical systems like these. The potential points of failure were concerning: if the Windows machine's hard drive were to become corrupted, both sides of the dispenser would go offline. Moreover, a simple browser or media player bug could compromise or obscure the refueling data—a serious issue for a measurement device.

Redesigning for Reliability

In designing the new calculator, my first priority was to eliminate any single point of failure. I achieved this by splitting video handling into two independent systems, one for each side of the dispenser. This ensured that if one side failed, the other could continue operating.

I then chose Linux as the operating system and opted for a compact embedded board powered by an OMAP3 CPU as the hardware foundation. This combination provided greater reliability and robustness, essential for such a critical application.

Innovative Use of Hardware for Screen Composition

One unique feature of the OMAP3 chip was its capability to handle screen composition directly in hardware. This allowed two virtual displays to be merged at the hardware level, with the combined output shown on the screen.

In most systems, a windowing system and compositor handle the merging of multiple windows in software. This means that if something goes wrong—like a crash in the media player—it could potentially corrupt the part of the display showing critical refueling data. By leveraging the OMAP3's hardware-based screen composition, I effectively eliminated this failure mode, ensuring that the display of refueling data would remain intact and reliable, regardless of any issues with the media content.

Simplifying with DirectFB

For rendering the refueling data, I used a very simple and lightweight graphical library called DirectFB. This decision minimized the amount of code involved in displaying the data, adhering to the principle that less code generally translates to fewer bugs—a crucial consideration in the development of a reliable embedded system.

With the display handling portion designed and implemented, I turned my attention to what additional functionality could be integrated into the calculator. After some consideration, I decided to incorporate two additional features: a micro forecourt controller and a micro POS/EPS system.

Expanding Functionality: Forecourt Controller and POS/EPS System

The integration of the micro forecourt controller meant that the dispenser could operate independently without the need for a central forecourt controller, providing greater flexibility and resilience. Additionally, I added a micro POS/EPS system that enabled payments using QR codes, a feature that was gaining popularity at the time, with systems like SEQR and others leading the way.

By integrating these features, I transformed the calculator from a simple display unit into a more versatile and autonomous system capable of managing refueling and payments without relying on external systems. This not only enhanced the functionality but also added layers of redundancy and convenience, making the entire system more robust and user-friendly.

A Revolutionary, Yet Unrealized Innovation

With all these features combined, something truly unique was created: the first dispenser and forecourt system without any central points of failure.

This system was designed to operate autonomously, ensuring that even if one component failed, the rest would continue to function seamlessly. The combination of hardware-based screen composition, a lightweight and reliable display library, an integrated micro forecourt controller, and a micro POS/EPS system made this calculator a groundbreaking innovation in the industry.

However, like many good ideas, this one never made it to the production phase.

Despite its potential to revolutionize the market, various factors prevented it from reaching full-scale implementation. Yet, one thing remained undeniable—it was, in its own right:

The "one" calculator to rule them all.