SPI clock not configured — RadioLib default is 2 MHz

[carsten-walther]

File: variants/**/target.cpp

RADIO_CLASS radio = new Module(P_LORA_NSS, P_LORA_DIO_1, P_LORA_RESET, P_LORA_BUSY, spi);

Without explicit SPISettings, RadioLib uses the platform default—which is 2 MHz. According to the Semtech datasheet, the SX1262 supports SPI up to 16 MHz. All radio-internal operations run via SPI: getIrqFlags(), getCurrentRSSI(), startReceive(), startTransmit(), readData(), getPacketLength(). At 2 MHz, a single 16-bit IRQ read (including SPI overhead) takes ~10–15 µs. At 8 MHz, this drops to ~3–4 µs.

Impact: isReceivingPacket() is called on every checkSend() call in the main loop and reads the IRQ flags via SPI. Likewise, getCurrentRSSI() is used for noise floor calibration (64 samples × SPI read). Any reduction in SPI latency directly improves the loop frequency.

Suggestion: Module constructor with an explicit SPISettings parameter (RadioLib ≥ 6.x).

File: variants/**/target.cpp

RADIO_CLASS radio = new Module(P_LORA_NSS, P_LORA_DIO_1, P_LORA_RESET, P_LORA_BUSY, spi, SPISettings(8000000, MSBFIRST, SPI_MODE0));