Co-Developing an App Store App and Bare-Metal RP2350 Firmware with a Shared Swift Core and STL-Backed Digital Twin
Waiting for PCB fabrication and 3D-printed enclosures usually creates a painful bottleneck in hardware startups: firmware engineers wait for boards to arrive, while app developers build UI mockups that drift away from the physical device.
To build StackCalc—a kid-friendly, exam-legal RPN scientific and educational calculator that grows with learners from StackCalc 6 (Common Core K–6) to StackCalc 32 (AP Calculus and engineering)—we architected our software and mechanical CAD pipelines so the iOS/iPadOS/watchOS App Store app and our bare-metal Raspberry Pi RP2350 firmware share a single Swift codebase (RPNCore) and co-develop against an STL-backed Digital Twin.