The evolution of the automobile is a fascinating journey, marked by groundbreaking innovations that have continually reshaped how we drive and interact with our vehicles. Among these pivotal advancements, the introduction of the Engine Control Unit (ECU) stands out as a watershed moment, heralding the era of automotive electronics and paving the way for the sophisticated, intelligent cars we know today. When we talk about the first car with an ECU, we’re not just discussing a mere technological upgrade; we’re delving into the genesis of modern automotive brains.
Bendix Electrojector: The Pioneering ECU System
The title of “world’s first Engine Control Unit (ECU)” is widely attributed to the Electrojector system developed by the Bendix Corporation, now a part of Honeywell International Inc. This pioneering system debuted in 1957, making its way into select 1958 models of Chrysler, specifically the prestigious Chrysler 300D and the luxurious Chrysler Imperial.
The Electrojector wasn’t just a minor tweak; it was a bold leap into the realm of electronic fuel injection (EFI). At its heart was an Electronic Control Unit (ECU), a revolutionary component designed to precisely manage fuel delivery to the engine. This ECU acted as the brain of the system, diligently processing data from various sensors to optimize engine performance. By monitoring inputs and controlling fuel injection, the Electrojector aimed to enhance efficiency and power, a stark contrast to the mechanical fuel injection systems prevalent at the time.
However, like many groundbreaking innovations, the Electrojector system wasn’t without its challenges. Reliability issues plagued its early deployment, leading to its unfortunate discontinuation shortly after its introduction. Despite its short lifespan, the Bendix Electrojector remains a monumental achievement. It laid the crucial foundation for all modern engine control units, demonstrating the potential of electronics in engine management and inspiring future generations of automotive engineers. It was the first car with an ECU system, even if it was a nascent technology.
Bosch D-Jetronic: Refining the ECU Concept
The story of the ECU didn’t end with the Electrojector. Recognizing the potential of this technology, Bosch, the renowned German automotive component supplier, acquired the Electrojector patents. Bosch embarked on a mission to refine and perfect the system, leading to the birth of the Bosch D-Jetronic in 1967. The “D” in D-Jetronic stands for “Druck,” the German word for pressure, highlighting the system’s reliance on pressure sensors for operation.
The D-Jetronic marked a significant step forward. While still utilizing analog circuitry and eschewing microprocessors or digital logic, its ECU was a marvel of engineering for its time. Housing approximately 25 transistors, this analog ECU efficiently handled sensor inputs and controlled fuel injection with greater sophistication than its predecessor. This system found its way into a range of European vehicles, showcasing its versatility and growing acceptance within the automotive industry:
- Mercedes-Benz: 250E, 280, 300, 350, 450
- Porsche: 914
- Saab: 99E
- Volkswagen: Type 3 & 4
- Volvo: 1800E, 1800ES, 142, 144, 164E
- Citroën: SM, DS
- BMW: 3.0Si (early types)
- Jaguar XJ-S, XJ12
Interestingly, the D-Jetronic system, with a Lucas-designed timing mechanism and Lucas branding on certain components, persisted in use until 1979 in Jaguar V12 engines (XJ12 and XJ-S), demonstrating its lasting impact.
L-Jetronic and LH-Jetronic: Embracing Airflow and Digital Control
Building on the pressure-controlled analog architecture of the D-Jetronic, Bosch introduced the L-Jetronic system. The “L” signifying “Luft,” German for air, indicated a shift towards airflow-based control. The L-Jetronic ECU, still analog, embraced custom-designed integrated circuits. This evolution resulted in a simpler and more reliable ECU compared to the D-Jetronic, furthering the practicality and adoption of electronic engine management.
The L-Jetronic systems paved the way for the digital revolution in fuel injection with the LH-Jetronic. Introduced in 1982 in California-bound Volvo 240 models, LH-Jetronic marked the arrival of digital fuel injection. Predominantly adopted by Scandinavian automakers and manufacturers of sports and luxury vehicles produced in smaller volumes like Porsche 928, LH-Jetronic came in variants such as LH 2.2 and LH 2.4. LH 2.2 utilized an Intel 8049 (MCS-48) microcontroller, typically with 4 kB of program memory, while LH 2.4 employed a Siemens 80535 microcontroller (based on Intel’s 8051/MCS-51 architecture) and a more substantial 32 kB program memory on a 27C256 chip.
These early ECUs, from Electrojector to LH-Jetronic, addressed critical pain points for drivers of the era. They offered solutions for:
- Cold start management: Ensuring reliable engine starts in cold weather.
- Fuel economy: Significantly improving fuel efficiency.
- Emissions control: Managing and reducing harmful exhaust emissions.
- Engine diagnostics: Providing basic diagnostic capabilities.
- Idle speed control: Maintaining stable engine idling.
The Rise of Microprocessors and Automotive Electronics
The late 1970s and early 1980s witnessed the burgeoning influence of microprocessors in automotive technology. In 1978, Cadillac pioneered a microprocessor-controlled “trip computer” in their Seville model, powered by a custom Motorola 6802 microcontroller. Concurrently, Ford introduced its Electronic Engine Control systems (EEC-1 & EEC-2), leveraging Toshiba’s 8-bit TLCS-12 PMOS microcontrollers.
The underlying catalyst for this electronic revolution was the advancement of metal–oxide–semiconductor (MOS) technology. The invention of the MOSFET (MOS field-effect transistor) in 1959 at Bell Labs paved the way for the power MOSFET by Hitachi in 1969 and, crucially, the single-chip microprocessor by Intel in 1971. These semiconductor breakthroughs made compact, powerful, and reliable electronic control units a practical reality for automotive applications.
The 1980s truly became the decade where power electronics began to permeate all facets of automotive design. This electronic integration expanded beyond just engine management to encompass:
- Transmission electronics
- Chassis electronics
- Passive safety systems
- Driver assistance features
- Passenger comfort and entertainment systems
- Integrated electronic cockpits
This widespread adoption of electronics fundamentally transformed the automobile, leading to the sophisticated and feature-rich vehicles we experience today.
Microcontrollers Through the Decades: A Timeline of Automotive Brainpower
The journey of the ECU is intrinsically linked to the evolution of microcontrollers. Let’s explore some key microcontrollers that shaped automotive electronics across different decades:
1980 to 1990: Early Integration
The 1980s marked a period of increasing, though still relatively basic, integration of microcontrollers in vehicles. Some notable examples include:
- Intel 8051: Despite its late 1970s introduction, the 8051 remained a versatile and widely adopted microcontroller in 1980s automotive applications.
- Motorola MC6805: Launched in the early 1980s, the MC6805 found its niche in automotive control systems, including early engine management.
- Intel 80186 and 80188: These early 1980s microprocessors saw limited use in automotive control and monitoring.
- Hitachi H8 Family: Emerging in the mid-1980s, the H8 family gained traction in automotive control and embedded systems.
- Zilog Z80: While famous for personal computers, the Z80 also had limited applications in 1980s automotive electronics.
Microcontroller usage in the 1980s was often focused on specific, less complex functions like engine control and basic electronic systems, a precursor to the more comprehensive integration to come.
1990 to 2000: Expanding Functionality
The 1990s witnessed a significant expansion in automotive electronics, with microcontrollers taking on more diverse roles. Key examples include:
- Motorola MPC5xx Series: Introduced in the mid-1990s, the MPC5xx series became a workhorse in automotive ECUs, particularly for advanced engine control.
- Intel 80C196 Family: This early 1990s family served in various automotive control systems, including engine management.
- Mitsubishi 16-bit Microcontrollers: Mitsubishi’s 16-bit offerings from this era contributed to enhanced control and monitoring capabilities.
- Microchip PICmicro Microcontrollers: The early 1990s PICmicro family found broad application in embedded systems, including automotive controls.
- Hitachi SH-2 and SH-3: The early 1990s SuperH (SH) series gained prominence in automotive ECUs.
- STMicroelectronics ST10 Family: Launched in the late 1990s, the ST10 family was specifically designed for automotive applications, including body electronics and engine control.
These microcontrollers of the 1990s drove the evolution of automotive electronics, enabling more sophisticated control and laying the groundwork for future advancements.
2000 to 2010: Power and Specialization
The first decade of the 21st century saw accelerated progress, with more powerful and specialized microcontrollers entering the automotive market:
- Freescale (NXP) MPC55xx and MPC56xx Series: Building on the MPC5xx success, these mid-2000s series offered enhanced performance for demanding powertrain applications.
- Renesas RH850 Series: Launched in the mid-2000s, the RH850 series was purpose-built for automotive control, including powertrain and body systems.
- Infineon TriCore AURIX: The late 2000s AURIX family, with its TriCore architecture, prioritized safety-critical automotive applications.
- STMicroelectronics SPC5 Series: Introduced in the late 2000s, the SPC5 family targeted a wide range of automotive applications, from engine management to safety systems.
- Microchip dsPIC DSCs: The early 2000s dsPIC family (Digital Signal Controllers) excelled in automotive tasks like motor control and power management.
- Texas Instruments C2000 Series: With real-time control focus, the C2000 series found use in automotive motor control and power electronics.
These advanced microcontrollers facilitated the integration of sophisticated features like electronic stability control, adaptive cruise control, and refined engine management systems.
2010 to 2020: The Rise of Complexity and Connectivity
The period from 2010 to 2020 marked an era of unprecedented complexity and connectivity in automotive electronics:
- NXP S32K1 and S32K3 Series: Expanding on the S32K legacy, these 2010s series emphasized enhanced performance, security, and connectivity for modern automotive needs.
- Infineon AURIX 2nd Generation: Building on the original AURIX, the 2nd generation addressed the escalating demands for automotive safety and performance.
- Renesas R-Car Series: While known for processors, the R-Car series also included microcontrollers for infotainment and advanced driver-assistance systems (ADAS).
- STMicroelectronics SPC58 Series: The 2010s SPC58 family catered to diverse automotive applications, including powertrain, safety, and body control.
- Texas Instruments TMS570 Series: The TMS570 series continued its evolution, providing real-time control for safety-critical automotive functions.
- Microchip SAM V7 Series: The 2010s SAM V7 series delivered high-performance solutions for demanding automotive applications, including communication and motor control.
These powerful microcontrollers were instrumental in enabling transformative automotive technologies like autonomous driving, connected car functionalities, and advanced safety systems. The market reflects this growth: the Automotive Microcontrollers Market, valued at USD 11.56 Billion in 2022, is projected to reach USD 21.64 Billion by 2030, with an impressive CAGR of 8.15% from 2023 to 2030. The increasing electrification of vehicles by OEMs and tier-one suppliers is expected to further fuel the proliferation of microcontrollers in automobiles.
From the pioneering Bendix Electrojector, the first car with an ECU system, to the sophisticated microcontrollers powering today’s vehicles, the journey of automotive electronics is a testament to continuous innovation. As we move towards an increasingly autonomous and connected automotive future, the ECU and its underlying microcontroller technology will undoubtedly remain at the heart of automotive progress.
