Advice Needed: Stick with RPi CM4 or Switch to Rockchip (RK3568/RK3588) for Qt/QML HMI in Coffee Machine?
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Hi everyone,
I'm Jawahar from Coimbatore, India, and our team is developing an HMI (Human-Machine Interface) for a commercial tea/coffee vending machine. We're using Qt/QML for the touchscreen UI (beverage selection, customizations like strength/size/milk/sugar, progress bars, maintenance alerts, etc.). The prototype is already half-developed, and we're now evaluating hardware options for production scaling.
Current Setup:We're using the Raspberry Pi Compute Module 4 (CM4) with a customized Raspberry Pi OS image optimized for Qt development (eglfs backend, hardware acceleration enabled).
Everything runs smoothly so far: responsive QML interfaces, touch inputs, and integration with peripherals (sensors for water levels, pumps, etc.).
We're relying on prebuilt 32-bit libraries in our Qt project (due to some legacy dependencies).Doubts/Questions:
Can we continue with RPi CM4 for commercial production?
Is there any issue with reselling/commercial use of RPi CM4-based products (e.g., licensing, certifications like BIS in India, or supply chain reliability in 2026)? We've heard about past shortages—has that improved? Any gotchas for vending machine applications (e.g., industrial temp range, EMC for motors/pumps near the board)?Cost and Performance Comparison: RPi CM4 vs Rockchip
We're considering cost savings with Rockchip alternatives. Which one provides better performance with Qt/QML (smooth animations, low latency touch response, video thumbnails if needed)?
RPi CM4 (our baseline).
RK3568 (seems mid-range, cost-effective).
RK3588 (flagship but pricier).Specific concerns: Our project uses 32-bit libs—does Rockchip support 32-bit Qt well, or is there a performance hit vs 64-bit? Any driver/Mali GPU issues for eglfs on Rockchip?
Which Processor to Prefer?
Based on factors like:
Qt/QML ecosystem support (pre-built packages, community resources).
Long-term availability/supply in India (local distributors like Element14/RS for RPi vs importers for Rockchip).
Power efficiency/heat (machine is always-on, no fan preferred).
Migration effort from our current CM4 setup (recompiling Qt, testing peripherals).
Future-proofing (e.g., adding AI/camera features later).What are the pros/cons of switching now vs sticking with CM4?
Additional Points to Confirm:
Browser performance (e.g., if we add web-based updates or YouTube tutorials in the HMI—RK3288 was laggy in testing).
Industrial certifications and longevity (support until 2030+?).
Pin-compatibility or carrier board reuse (we have a custom carrier for CM4—any Rockchip CM4-form-factor clones?).
Real-world examples of Qt HMIs on these processors in vending/appliances.
Cost breakdown for 100–500 unit runs (SOM price + dev time savings).
Any hidden costs/risks in switching (e.g., Rockchip vendor kernels vs RPi mainline).We're aiming for a balance of cost, reliability, and ease of development. Any experiences, benchmarks, or advice from those who've built similar Qt-embedded projects would be super helpful!
Thanks in advance!
Jawahar