Hello everyone,
I am developing a cellular IoT device using STM32L4 + SIM7600G-H 4G module. The goal is to create a highly reliable driver that can handle every possible disconnection, network drop, MQTT event, and recovery scenario without losing data or getting stuck.
Requirements:
- Heavy use of UART DMA (Circular RX buffer + IDLE line detection)
- Full finite state machine for modem management (Power on → Network → PDP → MQTT → Operational → Recovery)
- Robust parsing of all URCs (+CMQTTDISC, +CLOSED, registration changes, etc.)
- MQTT communication with ThingsBoard (telemetry, client attributes, shared attributes, RPC, firmware OTA/FOTA)
- Reliable reconnection logic with exponential backoff, message queuing during offline periods, and modem watchdog (power cycle on repeated failures)
Questions:
- What is currently the best recommended way in 2026 to implement such a driver on STM32L4?
- Has anyone successfully used X-CUBE-CELLULAR with SIM7600 series? Is it worth porting, or is it too LPWAN-oriented for a Cat.1 module like SIM7600G-H?
- Would you recommend:
- Custom AT command layer + MaJerle-style UART DMA + own FSM
- Porting TinyGSM logic into STM32 HAL
- Using SIMCOM’s built-in AT+CMQTT* commands with custom state machine
- Or another middleware / example I might have missed?
- Any production-grade open source projects or examples for SIM76xx on STM32L4/L5 that handle long-term stability (days/weeks of operation)?
I prefer maximum control and resilience over ease of use, so I’m ready to implement a solid custom solution if needed.
Any guidance, experiences, or recommended repositories would be greatly appreciated!
Thank you in advance.
Best regards,
Mohamed
