Sr. Embedded Software Engineer

MultiTech; Mounds View (MN); On-site; USD 110,000 - 170,000; Full time

Job summary

MultiTech seeks an experienced firmware engineer to design, develop, and maintain LoRaWAN module firmware and custom sensor apps. You will work across Mbed OS and Zephyr RTOS for STM32 and low-power Cortex-M MCUs, delivering AT command firmware and Class A/B/C protocol compliance.

You will port Zephyr BSPs, implement host-based tests, optimize ultra-low-power operation, and contribute to LoRa Alliance specs. This is a hands-on, production-focused role based in Minnesota.

Qualifications

• 5+ years bare-metal and RTOS firmware development on Arm Cortex-M (M0+, M3, M4)
• Strong C/C++ for resource-constrained MCUs (32KB RAM / 256KB Flash targets)
• LoRaWAN protocol stack implementation experience (MAC layer, Class A/B/C, regional parameters)
• STM32 family (STM32L151, STM32L4, STM32U3) peripherals and low-power modes
• Mbed OS 6.x application development and build system
• Zephyr RTOS device tree, Kconfig, west build system, subsystem development

Responsibilities

• Develop and maintain LoRaWAN module AT command firmware across multiple hardware variants
• Own the LoRaWAN MAC layer library — Class A/B/C operation, multicast, FOTA, ADR, regional parameter compliance
• Implement and validate LoRaWAN specification compliance including Class B beacon timing, ping-slot scheduling, and multicast
• Port and maintain Zephyr RTOS board support packages including board definitions, device drivers, and subsystem integration
• Develop custom LoRaWAN sensor applications using Mbed OS and Zephyr RTOS for customer-specific deployments
• Bring up and validate new hardware variants and component changes across the product line
• Design and execute comprehensive host-based test suites using CppUTest and Zephyr Twister
• Maintain bootloaders and FOTA update infrastructure for secure field updates
• Optimize power consumption for battery-operated devices targeting ultra-low-power sleep modes
• Support LoRa Alliance technical working group contributions (L2 protocol, payload schema)

Skills

Firmware development

RTOS experience

ARM Cortex-M

C/C++

Bare-metal

JTAG/SWD debugging

AT command interface

Git

CI/CD

Tools

Mbed OS

Zephyr RTOS

STM32 HAL/LL

west build system

Device tree

CppUTest

Zephyr Twister

Jenkins

Job description

The ideal candidate will design, develop, and maintain firmware for LoRaWAN module product lines (including xDot) and custom sensor applications. Work across Arm Mbed OS and Zephyr RTOS targeting STM32 and low-power Arm Cortex-M microcontrollers, delivering production AT command firmware, LoRaWAN Class A/B/C protocol compliance, and customer sensor solutions. This is the RTOS/RF-focused role required to continue LoRaWAN xDot development.

Responsibilities

• Develop and maintain LoRaWAN module AT command firmware across multiple hardware variants
• Own the LoRaWAN MAC layer library — Class A/B/C operation, multicast, FOTA, ADR, regional parameter compliance
• Implement and validate LoRaWAN specification compliance including Class B beacon timing, ping-slot scheduling, and multicast
• Port and maintain Zephyr RTOS board support packages including board definitions, device drivers, and subsystem integration
• Develop custom LoRaWAN sensor applications using Mbed OS and Zephyr RTOS for customer-specific deployments
• Bring up and validate new hardware variants and component changes across the product line
• Design and execute comprehensive host-based test suites using CppUTest and Zephyr Twister
• Maintain bootloaders and FOTA update infrastructure for secure field updates
• Optimize power consumption for battery-operated devices targeting ultra-low-power sleep modes
• Support LoRa Alliance technical working group contributions (L2 protocol, payload schema)

Qualifications

• 5+ years bare-metal and RTOS firmware development on Arm Cortex-M (M0+, M3, M4)
• Strong C/C++ for resource-constrained MCUs (32KB RAM / 256KB Flash targets)
• LoRaWAN protocol stack implementation experience (MAC layer, Class A/B/C, regional parameters)
• STM32 family (STM32L151, STM32L4, STM32U3) — peripherals, low-power modes, HAL/LL drivers
• Mbed OS 6.x application development and build system
• Zephyr RTOS — device tree, Kconfig, west build system, subsystem development
• JTAG/SWD debugging, logic analyzer, RF test equipment
• Git, CI/CD (Jenkins), automated firmware testing
• AT command interface design and implementation