In-Depth Look into the Automotive Instrument Cluster Architecture

Automotive instrument clusters are a crucial component of modern vehicles, providing drivers with vital information about the vehicle's performance and status. The automotive instrument cluster architecture has evolved significantly over the years, becoming increasingly complex with advancements in technology. In this article, we delve deep into the automotive instrument cluster architecture, exploring the hardware and software components, as well as other cluster design considerations. With various types of cluster development possible — segment LCD based, graphics based, or hybrid clusters — the underlying automotive instrument cluster architecture remains consistent across all variants.

Automotive Instrument Cluster Architecture — Hardware

At the heart of every automotive instrument cluster architecture lies a microcontroller (MCU) that is connected to various interfaces and devices. The following block diagram illustrates the hardware architecture:

The system typically operates on the 12V vehicle battery and is designed to handle input fluctuations ranging from 8V to 36V.

As the nervous system of the automobile, instrument cluster development with CAN and LIN is central to acquiring vehicle information from multiple ECUs. The CAN bus delivers high-speed powertrain and chassis data, while the LIN bus handles lower-speed body electronics signals. Instrument cluster development with CAN and LIN therefore requires both transceiver hardware and a robust software stack capable of parsing dozens of signals in real time.

• Digital Inputs: The automotive instrument cluster architecture receives digital inputs from various sources. One crucial digital input pertains to the ignition switch state, identified through a 0 to 12V input. Other inputs such as steering wheel or handlebar keys enable user interaction.
• Analog Inputs: An array of analog inputs is fed into the cluster and digitized using Analog-to-Digital Converters (ADCs). One example is the fuel level sensor, typically represented as a resistance load ranging from 5 to 500 ohms. The outside ambient temperature (OAT) can be obtained through a 10 to 100K ohm channel. Analog inputs can also represent switches implemented as potential dividers.
• Digital Outputs: The automotive instrument cluster architecture utilizes digital outputs to drive tell-tales, typically high-power LEDs, triggered based on specific events or fault conditions.
• PWM Outputs: Pulse Width Modulation outputs are crucial for controlling the brightness of the graphics LCD backlight. PWM outputs can also drive stepper motors when dedicated drivers are unavailable, and drive buzzers or speakers with output frequencies from 200 Hz to 20 kHz.
• Pulse Inputs: Some automotive instrument cluster architectures utilize a pulse counter to calculate RPM information from an encoder.
• Other Interfaces: Depending on the display type, the automotive instrument cluster can utilize a segment driver or TFT driver interface. Optional touch interfaces can also be incorporated. The cluster can integrate peripherals such as a rear-view camera via a dedicated camera input, accelerometers/gyro sensors, and ambient light sensors over I2C. Extended memory can be accessed through SPI/QSPI/SD interfaces. Bluetooth/BLE modules and Wi-Fi connectivity features are also possible within the automotive instrument cluster architecture.

Automotive Instrument Cluster Architecture — Software

As a mandatory system within an automobile, the automotive instrument cluster architecture's software layer should be robust and modular, ensuring reliable performance and ease of maintenance.

• Digital Inputs: The system only boots up or starts running the application if the ignition switch is on. Otherwise, the automotive instrument cluster is powered off or put in deep sleep mode to conserve power.
• Analog Inputs: Analog-to-digital conversion poses challenges due to varying voltage references and a noisy environment. Complex reference re-calculation mechanisms are necessary to calculate input voltage regardless of the current battery supply level. Suitable filter designs eliminate noise components.
• Digital Outputs: Software logic must be implemented to toggle LEDs at specified intervals and patterns, indicating various types of faults or events.
• PWM Outputs: Based on luminous level or headlight condition, the software must control the backlight brightness. Stepper motors require PID-based software filters for smooth movements. PWM outputs can also create sound effects using frequency and timing tables.

UX Related Cluster Design Considerations

In addition to hardware and software, there are several other cluster design considerations that engineers must address. Ergonomics is one such consideration — the automotive instrument cluster should allow the driver to access and interpret information quickly and comfortably, minimizing distractions and enhancing safety.

Customization and personalization are also key considerations in the modern automotive instrument cluster architecture. With digital displays, clusters can now offer customizable layouts allowing drivers to personalize the information displayed, colour schemes, and overall theme. The durability and reliability of the automotive instrument cluster are equally important — it must withstand temperature variations, vibrations, and electromagnetic interference throughout the vehicle's lifespan.

i mx rt1170 Based Digital Cluster and Connectivity Stack for Clusters

Modern automotive instrument cluster architecture increasingly leverages high-performance MCUs such as the i mx rt1170 based digital cluster platform from NXP. The i mx rt1170 based digital cluster combines dual-core Cortex-M7/M4 processing with a dedicated 2D graphics accelerator, enabling smooth animations and multi-layer compositing without a discrete GPU. To complement the rendering capability, a robust connectivity stack for clusters is required — covering CAN-FD, LIN, Ethernet, Bluetooth, and Wi-Fi. The connectivity stack for clusters manages protocol parsing, signal multiplexing, and OTA update plumbing, all within the timing constraints demanded by the automotive instrument cluster architecture. Embien has delivered production programs on the i mx rt1170 based digital cluster and similar SoCs. Explore our cross-domain embedded services to learn how we apply this expertise across automotive, industrial, and two-wheeler cluster programs.

Instrument Cluster Development with CAN and LIN Integration

Successful instrument cluster development with CAN and LIN requires more than simple transceiver integration. The automotive instrument cluster architecture must define the CAN database (DBC file), signal scaling and offset tables, LIN descriptor (LDF) files, and diagnostic message handling (UDS). Instrument cluster development with CAN and LIN also involves rigorous testing using CANoe, Vector tools, or similar environments to validate signal accuracy and timing under all operating conditions. Our Qt application development services complement instrument cluster development with CAN and LIN by providing a cross-platform HMI framework that can render CAN-sourced data with minimal latency on the automotive instrument cluster display.

Embien Expertise in Cluster Development

At Embien, we possess extensive expertise in the full scope of automotive instrument cluster architecture. Our team of skilled engineers and designers has a deep understanding of the hardware and software components involved, as well as the design considerations that determine production success. With a focus on innovation and user experience, we strive to create automotive instrument clusters that seamlessly integrate into vehicles, provide accurate information, and enhance the driving experience. Our engineers are knowledgeable in AUTOSAR and functional safety, ensuring cluster development is carried out at the highest class possible. Our credentials include turnkey design and delivery of stepper-motor based, segment-LCD based, graphic LCD based, and hybrid automotive instrument clusters for both ICE and EV vehicles.

Conclusion

In conclusion, the automotive instrument cluster architecture — encompassing hardware, software, instrument cluster development with CAN and LIN, connectivity, and UX design considerations — works together to create a seamless user experience. By comprehending this architecture, we can design automotive instrument clusters that meet specific requirements, provide accurate information, and enhance the overall driving experience.