examples: WIP on adding LoRa AT command set implementation

Signed-off-by: deadprogram <ron@hybridgroup.com>

examples/lora/atcmd/main.go

@@ -0,0 +1,47 @@
+// AT command set console running on the device UART to communicate with
+// an attached LoRa device.
+//
+// Computer <-> UART <-> MCU <-> SPI <-> SX126x/SX127x
+//
+// Connect using default baudrate for this hardware, 8-N-1 with your terminal program.
+// For details on the AT command set, see:
+// https://files.seeedstudio.com/products/317990687/res/LoRa-E5%20AT%20Command%20Specification_V1.0%20.pdf
+package main
+
+import (
+	"machine"
+	"time"
+)
+
+// change these to test a different UART or pins if available
+var (
+	uart = machine.Serial
+	tx   = machine.UART_TX_PIN
+	rx   = machine.UART_RX_PIN
+	input = make([]byte, 0, 64)
+)
+
+func main() {
+	uart.Configure(machine.UARTConfig{TX: tx, RX: rx})
+
+	for {
+		if uart.Buffered() > 0 {
+			data, _ := uart.ReadByte()
+
+			switch data {
+			case 13:
+				// return key
+				if err := parse(input); err != nil {
+					uart.Write([]byte("ERROR: "))
+					uart.Write([]byte(err.Error()))
+					crlf()
+				}
+				input = input[:0]
+			default:
+				// just capture the character
+				input = append(input, data)
+			}
+		}
+		time.Sleep(10 * time.Millisecond)
+	}
+}