Module sx127x 

Semtech SX1276, SX1277, SX1278, and SX1279 transceivers, and the modules built on them such as the RFM95W.

These radios are run through registers. The host writes the carrier, the modem, and the amplifier settings into them, fills the data buffer through RegFifo, and sets the operating mode in RegOpMode to transmit or receive, and RegIrqFlags reports how it went. The SX1276/77/78/79 datasheet (Rev 7) describes the registers, and this module carries them as data:

• register - the register addresses, the SPI address byte, and the operating modes.
• irq - the LoRa interrupt flags.
• status - the signal levels of a received packet and the modem’s live state.
• config - the frequency word, the LoRa modem settings a LinkSettings turns into, the amplifier and current limit settings, the sync word, the IQ polarity, and the register values of the errata.

The four chips share their registers and differ in the bands they cover, and the SPI interface cannot see which amplifier output a module wires to its antenna, so the caller names it. With the embedded-hal feature, the Sx127x driver resets the chip, calibrates its receiver at the carrier, and follows the datasheet’s transmit and receive sequences.

Modules

config

The settings an SX127x is configured with in LoRa mode, and the values its registers take.

irq

The SX127x LoRa interrupt flags.

register

The SX127x register map, its SPI framing, and its operating modes.

status

What an SX127x reports back in LoRa mode: the signal levels of a packet and the modem’s state.

Structs

Board

How a module wires its SX127x: the amplifier output on its antenna and its clock.

RadioConfig

What a radio sends and listens with: the carrier, the LoRa link, the power, and the sync word and IQ polarity that keep one network apart from another.

Sx127x

A Semtech SX1276, SX1277, SX1278, or SX1279 on an SPI bus, with its NRESET line.

Enums

RadioError

What can go wrong driving an SX127x.

Reception

How a reception ended.

Constants

CALIBRATION_LIMIT_US

How long a calibration may run before the driver gives up, in microseconds. The datasheet says it takes about 10 ms.

CALIBRATION_POLL_US

How often RegImageCal is read while a calibration runs, in microseconds.

IRQ_POLL_US

How often the interrupt flags are read while a frame goes out or comes in, in microseconds.

RESET_HOLD_US

How long NRESET is held low, in microseconds. The datasheet’s Manual Reset section asks for a hundred microseconds; this is the 1 ms Semtech’s LoRaMac-node holds it for.

RESET_SETTLE_US

How long to wait after releasing NRESET, in microseconds. The datasheet asks for 5 ms; this is the 6 ms LoRaMac-node waits.

TIMEOUT_MARGIN_US

How much longer than a frame’s airtime a transmission may take before the driver gives up on it, in microseconds.