Add embassy-lora crate

This crate contains async radio drivers for various lora drivers that
work with embassy timers. The code is imported from Drogue Device (
https://github.com/drogue-iot/drogue-device)

The radio drivers integrate with the async LoRaWAN MAC layer in the
lorawan-device crate.

Also added is an example for the STM32WL55 and for STM32L0 (requires
the LoRa Discovery board) for LoRaWAN. Future work is to make the
underlying radio drivers using fully async SPI when communicating
with the peripheral.

embassy-lora/src/sx127x/sx127x_lora/register.rs

@@ -0,0 +1,107 @@
+// Copyright Charles Wade (https://github.com/mr-glt/sx127x_lora). Licensed under the Apache 2.0
+// license
+//
+// Modifications made to make the driver work with the rust-lorawan link layer.
+#![allow(dead_code, clippy::enum_variant_names)]
+
+#[derive(Clone, Copy)]
+pub enum Register {
+    RegFifo = 0x00,
+    RegOpMode = 0x01,
+    RegFrfMsb = 0x06,
+    RegFrfMid = 0x07,
+    RegFrfLsb = 0x08,
+    RegPaConfig = 0x09,
+    RegPaRamp = 0x0a,
+    RegOcp = 0x0b,
+    RegLna = 0x0c,
+    RegFifoAddrPtr = 0x0d,
+    RegFifoTxBaseAddr = 0x0e,
+    RegFifoRxBaseAddr = 0x0f,
+    RegFifoRxCurrentAddr = 0x10,
+    RegIrqFlagsMask = 0x11,
+    RegIrqFlags = 0x12,
+    RegRxNbBytes = 0x13,
+    RegPktSnrValue = 0x19,
+    RegModemStat = 0x18,
+    RegPktRssiValue = 0x1a,
+    RegModemConfig1 = 0x1d,
+    RegModemConfig2 = 0x1e,
+    RegSymbTimeoutLsb = 0x1f,
+    RegPreambleMsb = 0x20,
+    RegPreambleLsb = 0x21,
+    RegPayloadLength = 0x22,
+    RegMaxPayloadLength = 0x23,
+    RegModemConfig3 = 0x26,
+    RegFreqErrorMsb = 0x28,
+    RegFreqErrorMid = 0x29,
+    RegFreqErrorLsb = 0x2a,
+    RegRssiWideband = 0x2c,
+    RegDetectionOptimize = 0x31,
+    RegInvertiq = 0x33,
+    RegDetectionThreshold = 0x37,
+    RegSyncWord = 0x39,
+    RegInvertiq2 = 0x3b,
+    RegDioMapping1 = 0x40,
+    RegVersion = 0x42,
+    RegTcxo = 0x4b,
+    RegPaDac = 0x4d,
+}
+#[derive(Clone, Copy)]
+pub enum PaConfig {
+    PaBoost = 0x80,
+    PaOutputRfoPin = 0,
+}
+
+#[derive(Clone, Copy)]
+pub enum IRQ {
+    IrqTxDoneMask = 0x08,
+    IrqPayloadCrcErrorMask = 0x20,
+    IrqRxDoneMask = 0x40,
+}
+
+impl Register {
+    pub fn addr(self) -> u8 {
+        self as u8
+    }
+}
+
+impl PaConfig {
+    pub fn addr(self) -> u8 {
+        self as u8
+    }
+}
+
+impl IRQ {
+    pub fn addr(self) -> u8 {
+        self as u8
+    }
+}
+
+#[derive(Clone, Copy)]
+pub enum FskDataModulationShaping {
+    None = 1,
+    GaussianBt1d0 = 2,
+    GaussianBt0d5 = 10,
+    GaussianBt0d3 = 11,
+}
+
+#[derive(Clone, Copy)]
+pub enum FskRampUpRamDown {
+    _3d4ms = 0b000,
+    _2ms = 0b0001,
+    _1ms = 0b0010,
+    _500us = 0b0011,
+    _250us = 0b0100,
+    _125us = 0b0101,
+    _100us = 0b0110,
+    _62us = 0b0111,
+    _50us = 0b1000,
+    _40us = 0b1001,
+    _31us = 0b1010,
+    _25us = 0b1011,
+    _20us = 0b1100,
+    _15us = 0b1101,
+    _12us = 0b1110,
+    _10us = 0b1111,
+}