LoRa physical layer (the rustaceous radio)

Why?

• provide one straight-forward LoRa physical layer API which supports both LoRaWAN and point-to-point (P2P) use cases;
• support a variety of microcontroller unit (MCU) and LoRa chip combinations behind one API;
• enable LoRa features for any embedded framework which supports embedded-hal-async for the desired MCU/LoRa chip combination.

How?

• separate out modulation parameters and packet parameters as separate concerns to address the nuances in LoRa chip support and to allow flexible specification of various LoRaWAN and P2P send/receive channels, even in the same use case;
• allow the user to specify a LoRa chip kind (for example, Sx1261/2) and specific LoRa board type (for example, Stm32wlSx1262) and hide the control of that LoRa board behind the LoRa physical layer API;
• provide a minimal trait which must be implemented for each desired embedded framework/MCU type/LoRa chip type to allow this crate to interface to the LoRa chip within the embedded framework.

Wheretofore?

• while the current examples use the Embassy embedded framework, nrf52840, stm32wl, and stm32l0 MCUs, and Sx127x/Sx126x chips, this crate provides a path forward for other embedded frameworks, MCU types, and LoRa chips in a Rust development environment;
• some links below refer to a fork of Embassy in the ceekdee GitHub repository; however, the intent is to update Embassy to support this lora-phy crate;
• in order to demonstrate a LoRaWAN capability using the lora-phy crate, one must currently clone the ceekdee versions of rust-lorawan and embassy so that they are all under the same projects folder (that is, relative paths are used in Embassy Cargo.toml files to link to rust-lorawan). This restriction will be removed once the lora-phy crate is more fully tested.
• the original LoRa implementations in Embassy remain available after the update to support this lora-phy crate.

LoRa physical layer API

For users wishing to implement a LoRaWAN or P2P solution, the following implementation files provide the necessary context:

• the API itself;
• pertinent ancillary information.

Examples of API usage:

• stm32wl P2P send and sleep;
• stm32wl LoRaWAN using rust-lorawan;
• stm32l0 P2P receive continuous;
• nrf52840 duty cycle receive;
• nrf52840 channel activity detection.

Embedded framework/MCU support

For embedded framework developers wishing to add LoRa support as a feature for one or more MCU/LoRa chip combinations:

• the InterfaceVariant trait, which enables this lora-phy crate to interface to a specific embedded framework/MCU/LoRa chip combination.

Example InterfaceVariant implementations:

• Embassy stm32wl/Sx1262, stm32l0/Sx1276, and nrf52840/Sx1262

LoRa chip support

For developers wishing to add support for new LoRa chips or enhance support for existing chips:

• the RadioKind trait, which must be implemented for each kind of LoRa chip for access through the lora-phy crate API;
• the interface implementation, which captures the three key read/write operations allowing control of the LoRa chip from this crate through either opcode or register operations.

Example RadioKind implementations and ancillary information:

• the Sx1261/2 radio kind;
• the Sx1276/7/8/9 radio kind.

LoRa board-specific support

LoRa boards use LoRa chip features differently. To suppport these variations within a radio kind implementation, BoardType and ChipType are available:

• scroll to BoardType and ChipType.

One can add a LoRa board (the board name includes the chip type in case the board may include a range of chip types) and the ChipType, then modify the radio kind processing to support board-specific features. The ChipType is used for generic checks, alleviating the need to add a new board type check in places where a generic check will do. BoardType checks only need to be implemented where the specificity is board-related. There are examples of each type of check here:

• search for BoardType and ChipType.

Chat

A public chat on LoRa/LoRaWAN topics using Rust is here:

• Matrix room