Firmware Engineer Smart Metering & Cellular IoT

Job Summary

We are looking for an experienced Embedded Firmware Engineer with strong hands-on experience in STM32, Smart Metering, DLMS/COSEM, RS485/Modbus and GSM/4G/NB-IoT communication.

The candidate should have experience developing reliable firmware for smart/prepaid energy meters and IoT devices using Quectel, SIMCom or similar cellular modules, with MQTT/cloud connectivity.

Key Responsibilities

- Develop embedded firmware primarily on STM32 using C/C++ and FreeRTOS.
- Develop communication drivers for single-phase, three-phase, prepaid and smart energy meters.
- Implement DLMS/COSEM (IEC 62056) communication, OBIS codes, billing data, load profiles, instantaneous parameters and meter events.
- Develop RS485/Modbus RTU meter communication drivers.
- Integrate Quectel / SIMCom GSM, 4G LTE and NB-IoT modules using AT commands.
- Implement modem initialization, SIM/APN configuration, network registration, TCP/IP, MQTT/MQTTS and automatic reconnection.
- Integrate devices with AWS IoT Core using secure MQTT/TLS communication.
- Develop reliable OTA/FOTA, watchdog, modem recovery and store-and-forward mechanisms.
- Interface with pulse inputs, digital I/O and 4–20 mA analog sensors.
- Debug firmware and communication issues using JTAG/SWD, logic analyzers and serial/protocol debugging tools.
- Coordinate with hardware teams for board bring-up,



testing and field troubleshooting.

Required Skills
- 2+ years of relevant Embedded Firmware / IoT / Smart Metering experience.
- Robust Embedded C/C++ and STM32 development experience.
- Hands-on experience with FreeRTOS, UART, RS485, SPI, I2C, ADC, GPIO, timers, interrupts and watchdogs.
- Strong understanding of DLMS/COSEM, IEC 62056 and OBIS codes.
- Experience developing electrical meter communication drivers.
- Experience with Quectel / SIMCom cellular modules and AT commands.
- Knowledge of GSM/GPRS/4G LTE, NB-IoT and LTE-M.
- Experience with MQTT, TCP/IP, HTTP/HTTPS and TLS.
- Experience with AWS IoT Core or similar IoT cloud platforms.
- Understanding of smart/prepaid meters, AMR/AMI and industrial IoT systems.

Preferred Experience Experience with Secure, HPL, L&T;, Genus, Elmeasure or similar energy meters will be an advantage.

Knowledge of ESP32, LoRa/LoRaWAN and ChirpStack is desirable but secondary to STM32, cellular communication and smart metering experience.

Preferred Candidate Profile

Candidates with hands-on experience in STM32 + DLMS/COSEM + RS485/Modbus + Quectel/SIMCom + Smart Metering will be strongly preferred.

Perks & Benefits

- Competitive salary based on experience and skills.
- Opportunity to work on production-grade Smart Metering, Prepaid Metering and Industrial IoT products.

📌 Firmware Engineer - LoRaWAN/NB-IoT/WIFI (Bengaluru)
🏢 Mettsenia Solutions
📍 Bengaluru