sx127x: Driver for Semtech sx127x radio modules

This first version of the driver has been tested with BB-FRM9x module

examples/lora/sx127x/sender.go

@@ -0,0 +1,88 @@
+// Sends data with LoRa.
+package main
+
+import (
+	"fmt"
+	"machine"
+	"strconv"
+	"time"
+
+	"tinygo.org/x/drivers/lora/sx127x"
+)
+
+var loraConfig = sx127x.Config{
+	Frequency:       868100000,
+	SpreadingFactor: 12,
+	Bandwidth:       125000,
+	CodingRate:      6,
+	TxPower:         17,
+}
+
+const (
+	SPI_SCK_PIN = machine.PA5
+	SPI_SDO_PIN = machine.PA7
+	SPI_SDI_PIN = machine.PA6
+
+	SPI_CS_PIN  = machine.PB8
+	SPI_RST_PIN = machine.PB9
+	DIO0_PIN    = machine.PA2
+
+	UART_TX_PIN = machine.PA9
+	UART_RX_PIN = machine.PA10
+)
+
+func main() {
+
+	// Configure serial console
+	machine.Serial.Configure(machine.UARTConfig{TX: UART_TX_PIN, RX: UART_RX_PIN, BaudRate: 115200})
+
+	println("LoRa Sender Example")
+
+	// Prepare GPIOS (SPI + DIO)
+	machine.LED.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	SPI_CS_PIN.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	SPI_RST_PIN.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	DIO0_PIN.Configure(machine.PinConfig{Mode: machine.PinOutput})
+
+	// Enable SPI
+	machine.SPI0.Configure(machine.SPIConfig{
+		SCK:       SPI_SCK_PIN,
+		SDO:       SPI_SDO_PIN,
+		SDI:       SPI_SDI_PIN,
+		Frequency: 500000,
+		Mode:      0})
+
+	// Create and Reset Lora driver
+	loraRadio := sx127x.New(machine.SPI0, SPI_CS_PIN, SPI_RST_PIN)
+	loraRadio.Reset()
+
+	// Check module identification
+	if loraRadio.GetVersion() != 0x12 {
+		println("SX1276 module not found")
+		for {
+		}
+	} else {
+		println("Module version 0x12")
+	}
+
+	// Configure Lora settings (modulation, SF... etc )
+	var err = loraRadio.SetupLora(loraConfig)
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+
+	// Send a Lora packet every 5 sec
+	println("Sending LoRa packets every 5 seconds...")
+	for i := 0; ; i++ {
+		var packet = "TinyGo LoRa Sender: " + strconv.Itoa(i)
+		println("Sending:", packet)
+
+		machine.LED.Low()
+		time.Sleep(time.Millisecond * 150)
+		machine.LED.High()
+
+		loraRadio.TxLora([]byte(packet))
+		time.Sleep(5000 * time.Millisecond)
+	}
+}