ESP32 + RFM95: Avoiding Reset Hassles with the Right Library!

Common Issues with ESP32 + RFM95 Libraries & Reset Behavior
When using the RFM95 with ESP32, mismatched or outdated libraries often cause:

• Inconsistent initialization → module stays unresponsive until a manual reset (pulling RST low/high).

• SPI timeouts or hangs → library not synced with ESP32’s SPI bus speed or mode.

• Unsupported register mappings → using older LMIC/RadioHead versions that don’t fully support SX1276/78 chip revisions.

• Frequent watchdog resets → improper handling of IRQ/DIO pins during LoRa TX/RX cycles.

• Manual reset requirement → occurs when the reset pin isn’t controlled in software or the library fails to reinitialize the transceiver after wakeup.

Good Practices for Stable Operation

Choose the Right Library Version

• Use actively maintained LoRa libraries (e.g. Arduino-LMIC fork or Sandeep Mistry’s LoRa, depending on project needs).

• Check compatibility notes for ESP32 SPI drivers; newer ESP-IDF-based cores handle timing better.

Handle Reset Pin in Code

• Connect RFM95 RST pin to a GPIO on ESP32.

• Explicitly toggle reset during startup, before initializing LoRa.begin().

• Add a short delay (5–10 ms) after reset for stable startup.

Pin Mapping & SPI Bus Stability

• Verify DIO0/DIO1 mapping matches the library configuration.

• Keep SPI speed moderate (≤8 MHz) to avoid unstable transfers on longer traces.

A Practical Alternative
If you want to avoid the trial-and-error of library versions, SPI timing, and manual reset quirks, consider a ready-made LoRa-enabled board. For example, our STM32-based board integrates a sub-GHz transceiver with stable power management and optimized RF layout—helping you skip common software/hardware pitfalls while getting reliable long-range wireless right away.