Senior Embedded Software Engineer

Triton Environmental Consultants, Ltd.; Mounds View (MN); On-site; USD 110,000 - 140,000; Full time

Job summary

Triton Environmental Consultants, Ltd. is seeking an experienced firmware engineer to design, develop, and maintain LoRaWAN module firmware and custom sensor applications.

You will work across Mbed OS and Zephyr RTOS targeting STM32 and ARM Cortex-M microcontrollers to deliver production AT command firmware and LoRaWAN Class A/B/C support. The role emphasizes power optimization, secure field updates, porting Zephyr BSPs, and collaboration with hardware teams for new variants and customer

Qualifications

• 5+ years bare-metal and RTOS firmware development on Arm Cortex-M MCUs.
• Strong C/C++ for resource-constrained MCUs.
• LoRaWAN protocol stack experience (MAC, Class A/B/C).
• STM32 family peripherals and low-power modes.
• Mbed OS 6.x development and build processes.
• Zephyr RTOS: device tree, Kconfig, west-based builds.
• SPI/I2C peripherals and RF transceivers (SX1272/ SX1262).
• JTAG/SWD debugging and RF test equipment familiarity.
• Git-based workflows and Jenkins CI/CD pipelines.
• AT command interface design and implementation.

Responsibilities

• Develop and maintain LoRaWAN AT command firmware across hardware variants.
• Own the LoRaWAN MAC layer library — Class A/B/C operation, multicast, FOTA, ADR.
• Implement and validate LoRaWAN specification compliance (Class B timing, ping-slot).
• Port and maintain Zephyr BSPs including board definitions and drivers.
• Develop custom LoRaWAN sensor applications using Mbed OS and Zephyr.
• Bring up new hardware variants and component changes across the product line.
• Design and execute host-based test suites using CppUTest and Zephyr Twister.
• Maintain bootloaders and FOTA infrastructure for secure field updates.
• Optimize power consumption for ultra-low-power sleep modes.
• Support LoRa Alliance technical working group contributions.

Skills

Firmware development

Bare-metal & RTOS

C/C++ for constrained MCUs

LoRaWAN protocol Stack

ARM Cortex-M

Tools

Mbed OS

Zephyr RTOS

STM32 HAL/LL

JTAG/SWD debugging

Git / Jenkins CI

Job description

SUMMARY: 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.

ESSENTIAL DUTIES AND 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)

QUALIFICATION REQUIREMENTS:

• 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
• SPI/I2C peripheral drivers (SX1272/SX1276/SX1262 radio, external flash, EEPROM)
• JTAG/SWD debugging, logic analyzer, RF test equipment
• Git, CI/CD (Jenkins), automated firmware testing
• AT command interface design and implementation

PHYSICAL DEMANDS:

• Lifting requirements up to 25 pounds.
• Requires sitting for periods of time and occasional standing.
• Use hands to finger, handle or feel.

WORK ENVIRONMENT:

• Working conditions are normal for an office environment. Minimal noise.
• Our Minnesota facility includes a manufacturing environment. Moderate noise level. Machinery operation requires the use of safety equipment to include but not limited to; safety glasses, hearing protection, wrist and shoe straps, and ESD smock. Loose fitting clothing and jewelry are not permitted. No food allowed in the manufacturing area. No cell phone use allowed in manufacturing area unless approved by management.

EQUIPMENT AND TOOLS USED:

• Laptop computer
• Standard office equipment