Embien wished to create a next-generation digital cluster for the two-wheeler market as a technology demonstrator. The concept must meet soaring user expectations for smartphone-like interactivity and rich graphics on a cost-effective MCU.
The challenge was multifaceted: render smooth, 3D-effect animations, display turn-by-turn navigation data, and manage real-time smartphone connectivity (calls, messages) simultaneously. All this had to be achieved with extremely limited on-chip RAM (just 2MB) and processing power, without a high-level OS like Linux or Android. The solution required deep, hardware-level optimization to leverage the MCU’s 2D graphics engines and dual-core architecture effectively, all while ensuring a low-distraction, safe, and intuitive user interface for the rider.
Embien's team architected a comprehensive solution from the silicon up, proposing our Sparklet Embedded GUI library as the core HMI engine. Sparklet is specifically designed and optimized for microcontrollers like the i.MX RT1170, enabling rich graphics without the overhead of a traditional OS.
1. Dual-Core Asymmetric Multiprocessing (AMP) Architecture
Our first strategic decision was to leverage the i.MX RT1170’s dual-core nature. We designed an Asymmetric Multiprocessing (AMP) framework to isolate critical tasks:
Arm Cortex-M7 Core (1 GHz): This high-performance core was dedicated entirely to the HMI. It ran the Sparklet GUI library, processed user inputs, and managed all graphics rendering.
Arm Cortex-M4 Core (400 MHz): This efficient core was dedicated to real-time, critical vehicle functions. It ran the CAN stack, interfacing with the vehicle's ECUs to gather speed, RPM, fuel level, and warning indicators. It also managed the Bluetooth module and its communication stack.
This separation ensured that even under heavy HMI load like a complex screen transition while receiving a call notification the vital vehicle data collection and processing on the M4 core would never be interrupted or delayed.
2. Hardware-Accelerated Rendering with Sparklet GUI
The key to achieving a "premium" feel on an MCU was offloading the M7 core. Our Sparklet library's rendering pipeline was engineered to directly command the i.MX RT1170's built-in 2D graphics accelerators: the PxP (Pixel Pipeline) and the VGLite GPU.
Layer & Sprite Composition: Instead of "brute force" full-screen redraws by the CPU, Sparklet constructed the UI using the hardware's multiple display layers (up to 4) and hardware sprites (up to 18). The static background was on one layer, semi-dynamic elements (like gauges) on another, and active sprites (like a speedometer needle or turn indicator) on top.
Low-Overhead Animation: When the speedometer needle needed to move, the M7 CPU didn't recalculate thousands of pixels. It simply issued a command to the hardware to rotate the "needle" sprite. This hardware-accelerated rotation, scaling, and alpha-blending was the secret to the "smooth animation" our client required. This approach used minimal CPU cycles, leaving the M7 free to handle other UI logic.
3. Aggressive Memory Optimization
With only 2MB of on-chip SRAM, memory management was critical.
TCM for Performance: We allocated the 512KB of Tightly Coupled Memory (TCM) for the Cortex-M7 to hold the most critical frame buffers and Sparklet's core rendering routines, enabling zero-wait-state access for maximum performance.
On-the-Fly Asset Decoding: To display large, rich backgrounds for different themes, we didn't store decompressed bitmaps in the scarce SRAM. We leveraged the i.MX RT1170’s hardware JPEG decoder. Sparklet would command the decoder to read a compressed JPEG from external flash and write the decompressed pixels directly to the display frame buffer, completely bypassing the SRAM. This allowed for full-screen, high-resolution graphics with a near-zero RAM footprint.
4. Rapid HMI Workflow with Flint IDE
Our proprietary Flint IDE revolutionized the client's development workflow. The client's UI/UX designers worked in their preferred tool, Adobe Photoshop, creating stunning, multi-layered visuals.
Photoshop-to-Target: These Photoshop (PSD) files were imported directly into Flint. Flint automatically parsed the layers, assets, positions, and transparency, converting them into a Sparklet-compatible project.
Visual Logic & Animation: Our HMI developers then used Flint’s visual editor to define screen flows, link UI elements (like the fuel gauge) to data variables (from the M4 core), and build complex animations. This visual, drag-and-drop approach eliminated thousands of lines of manual C code.
This Photoshop-to-Flint-to-Target pipeline was so efficient that a fully interactive HMI prototype was "completed within weeks," not months.
5. Full-Stack Connectivity
Embien designed the prototype hardware with 5” and 7” LCD options and integrated the necessary peripherals. We developed the complete software stack for connectivity:
CAN Stack: A robust, real-time CAN stack ran on the M4 core.
Bluetooth (BLE) Module: We integrated an external BLE module over UART and developed the complete GATT profile for smartphone communication. This enabled features like call notifications (intimate/pick/reject), message alerts, and, most impressively, turn-by-turn navigation data streamed from a companion mobile app.
The final prototype delivered a fluid, customizable, and connected experience that rivaled high-end systems, all running on a cost-effective and power-efficient crossover MCU.
Drastically Reduced Time-to-Market:The Sparklet GUI library and Flint IDE’s Photoshop-to-target workflow compressed the entire HMI development lifecycle from months to weeks.
Premium HMI on a Cost-Effective MCU: Enabled smooth 3D-effect animations, customizable themes, and a full-featured connected experience on a low-cost, low-power i.MX RT1170.
Optimized Performance & Reliability:The dual-core (M7/M4) architecture and hardware-accelerated graphics ensured a fluid UI that never compromised critical, real-time vehicle functions.
Future-Proof & Scalable Design: The solution architecture allowed for easy UI customization (themes) and feature additions without requiring a hardware redesign.
Complete End-to-End Solution: Embien developed a full-stack service, from initial hardware design and low-level driver development to BLE protocol creation and final HMI application software.
This project demonstrates Embien’s deep expertise in automotive HMI design and embedded systems optimization. By harnessing the full potential of the i.MX RT1170 with our Sparklet GUI, we delivered a next-generation digital cluster that is both feature-rich and commercially viable. Our unique blend of hardware-aware software design and powerful development tools enables automotive OEMs and Tier 1s to build a connected, safe, and beautiful driving experience.
Contact Embien today to accelerate your next digital instrument cluster project and see what Sparklet can do for you.
Contact Embien to leverage our Sparklet GUI and i.MX RT expertise for your HMI.