Embedded Software Engineer

Legacy Health; München; Hybrid; EUR 70.000 - 90.000; Vollzeit

Zusammenfassung

HeyCharge in Munich develops an offline-first SecureCharge platform for EV charging with Zigbee mesh and BLE-based session authentication. You will ship firmware for chargers using Silicon Labs EFR32 and ESP32 hardware, focusing on a robust OTA path and secure boot in environments with no internet access.

The role emphasizes end-to-end ownership, cross-functional collaboration, and delivering highly reliable firmware in a constrained, offline-first ecosystem.

Qualifikationen

• 3+ years shipping embedded firmware on resource-constrained devices in production.
• Strong C++ in an embedded context with memory and RTOS trade-offs.
• Experience with at least one wireless stack (BLE, Zigbee, Thread) and willingness to learn others.
• Comfort with the full firmware lifecycle: bring-up, debugging with a logic analyzer/JTAG, OTA, diagnostics.
• Silicon Labs EFR32 family experience — Bluetooth and Zigbee stacks.
• ESP32 / ESP-IDF experience.
• OTA design and implementation, especially with partial-connectivity.
• Applied cryptography in embedded context — secure boot, key provisioning, signed updates.
• OCPP (any version) implementation or integration experience.

Aufgaben

• Design, implement, and ship firmware across our charger product line — EFR32/EFR32G23 plus ESP32 family — in C++.
• Wireless stacks: harden BLE session-authentication flow and Zigbee mesh coordinating loads.
• OCPP translation layer bridging offline-first protocol to external CPMSs/ OEMs.
• OTA pipeline: design and operate signed, resumable updates robust to limited connectivity.
• Security: cryptography, session tokens, signed messages, secure boot, factory key provisioning.
• Hardware bring-up: collaborate with hardware team on new board revisions and power budgeting.

Kenntnisse

C++ Embedded

RTOS

Wireless Stacks

Firmware Lifecycle

EFR32/Silabs

ESP32/ESP-IDF

OTA

Embedded Cryptography

OCPP

Tools

JTAG/Logic Analyzer

ESP-IDF Toolchain

Silabs EFR32 Toolchain

OTA Debugging Tools

Jobbeschreibung

Munich Full-Time €70,000–€90,000 per year · plus equity Reports to Head of Engineering

You’ll be working on devices that are genuinely unique — and on the critical path to delivering HeyCharge’s platform and technology at scale. Our embedded surface spans bootloader and secure boot, BLE session authentication, Zigbee mesh for inter-charger coordination, OCPP translation, store-and-forward cloud sync, and the OTA pipeline that updates all of it. One of our boards literally has an EFR32MG26, an EFR32FG23, and an ESP32 on the same PCB — three radios, three flash budgets, three sets of constraints to reconcile. The firmware is the product when the cellular signal dies in a concrete underground garage.

This role exists because embedded work is currently bottlenecked, and the platform’s roadmap is constrained by that. Your specific scope — which subsystems you own end-to-end vs. contribute to — will be calibrated to your background and where the team most needs leverage. The common factor: you’ll be shipping firmware that runs on hardware where there’s no internet rescue, no “patch it tomorrow,” and no second chance to get OTA right.

About HeyCharge

HeyCharge makes EV charging work in places it was never supposed to — underground garages, multi-tenant buildings, and any other concrete-and-rebar environment where cellular signal goes to die. Our offline-first SecureCharge platform uses Bluetooth for local session authentication and Zigbee mesh for inter-charger load management and cloud sync. No internet required at the charger; no compromise on reliability or billing accuracy.

We’re Munich-headquartered with team members across Germany, Ukraine, and the US, selling into property managers, utilities, and OEMs across Europe, the US, and Latin America. Our partners include Vonovia (Europe’s largest residential landlord), Easee and Emobi. We’re backed by Y Combinator and EU innovation funding, with a culture that’s Google-rooted on engineering, AI-first and automation-first on operations, and allergic to bureaucracy that doesn’t earn its keep.

Responsibilities

The embedded surface below is what our charger firmware covers in total. Your specific scope will be calibrated to your strengths and the team’s needs — you might own one of these end-to-end, or contribute across several.

• Firmware features: design, implement, and ship firmware across our charger product line — Silicon Labs EFR32MG26 and EFR32FG23 plus ESP32-family — in C++.
• Wireless stacks: build and harden the BLE session-authentication flow and the Zigbee mesh that coordinates load management across chargers in a building. Thread is a relevant direction.
• OCPP translation: the OCPP layer that bridges our offline-first protocol to the standards external CPMSs and OEMs expect.
• OTA pipeline: design and operate the OTA update flow — signed, resumable, robust to partial connectivity. The chargers our firmware runs on are physically hard to reach; failed updates are not an option.
• Security: cryptography that backs SecureCharge — session tokens, signed messages, secure boot, key provisioning at the factory.
• Hardware bring-up: partner with our hardware team on new board revisions — board bring-up, peripheral drivers, power budget reconciliation, debugging electrical-meets-software issues at the bench.

Qualifications

Required:

• 3+ years shipping embedded firmware on resource-constrained devices in production.
• Strong C++ in an embedded context — comfortable with memory-constrained design, RTOS scheduling, and the trade-offs between heap, stack, and statically-allocated state.
• Experience with at least one wireless stack (BLE, Zigbee, Thread, or similar) — and the willingness to learn the others.
• Comfort with the full firmware lifecycle: bring-up, debugging on the bench with a logic analyzer/JTAG, OTA, post-deploy diagnostics.
• Silicon Labs EFR32 family experience — particularly the Silabs Bluetooth and Zigbee stacks.
• ESP32 / ESP-IDF experience.
• OTA design and implementation, especially with partial-connectivity constraints.
• Applied cryptography in an embedded context — secure boot, key provisioning, signed updates.
• OCPP (any version) implementation or integration experience.

Nice-to-have:

• Embedded Linux for the gateway side of mixed-architecture deployments.
• Rust — we’re not Rust-first today, but we’re open to it where it earns its keep.

English fluency required; German is not.

Personal Characteristics

• Builder mindset — you create order, structure, and systems that make life easier; you reach for the oscilloscope before the Jira ticket.
• Ownership mentality — you take responsibility for the firmware you ship all the way through to deployed reality, including the parts that aren’t fun to debug.
• Automation-first — you instinctively look for ways to remove repetitive work, whether it’s flashing chips on a bring-up bench or running a regression suite against real hardware.
• Adaptable — you’re comfortable in a high-growth, ever-changing environment where the right answer this quarter might not be the right answer next quarter.