Client driver for WiFiNINA firmware (#98)

* wifinina: implementation of WiFiNINA driver, including:
   - TCP client example is working
   - reading sockets and mqtt working
   - switched over to common net package also used by espat package
   - smoke tests and updated README for wifinina

examples/wifinina/webclient/main.go

@@ -0,0 +1,153 @@
+// This example opens a TCP connection using a device with WiFiNINA firmware
+// and sends a HTTP request to retrieve a webpage, based on the following
+// Arduino example:
+//
+// https://github.com/arduino-libraries/WiFiNINA/blob/master/examples/WiFiWebClientRepeating/
+//
+package main
+
+import (
+	"fmt"
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers/net"
+	"tinygo.org/x/drivers/wifinina"
+)
+
+// access point info
+const ssid = ""
+const pass = ""
+
+// IP address of the server aka "hub". Replace with your own info.
+const server = "tinygo.org"
+
+// these are the default pins for the Arduino Nano33 IoT.
+// change these to connect to a different UART or pins for the ESP8266/ESP32
+var (
+
+	// these are the default pins for the Arduino Nano33 IoT.
+	uart = machine.UART2
+	tx   = machine.NINA_TX
+	rx   = machine.NINA_RX
+	spi  = machine.NINA_SPI
+
+	// this is the ESP chip that has the WIFININA firmware flashed on it
+	adaptor = &wifinina.Device{
+		SPI:   spi,
+		CS:    machine.NINA_CS,
+		ACK:   machine.NINA_ACK,
+		GPIO0: machine.NINA_GPIO0,
+		RESET: machine.NINA_RESETN,
+	}
+
+	console = machine.UART0
+)
+
+var buf [256]byte
+
+var lastRequestTime time.Time
+var conn net.Conn
+
+func main() {
+
+	uart.Configure(machine.UARTConfig{TX: tx, RX: rx})
+
+	// Configure SPI for 8Mhz, Mode 0, MSB First
+	spi.Configure(machine.SPIConfig{
+		Frequency: 8 * 1e6,
+		MOSI:      machine.NINA_MOSI,
+		MISO:      machine.NINA_MISO,
+		SCK:       machine.NINA_SCK,
+	})
+
+	adaptor.Configure()
+
+	connectToAP()
+
+	for {
+		loop()
+	}
+	println("Done.")
+}
+
+func loop() {
+	if conn != nil {
+		for n, err := conn.Read(buf[:]); n > 0; n, err = conn.Read(buf[:]) {
+			if err != nil {
+				println("Read error: " + err.Error())
+			} else {
+				print(string(buf[0:n]))
+			}
+		}
+	}
+	if time.Now().Sub(lastRequestTime).Milliseconds() >= 10000 {
+		makeHTTPRequest()
+	}
+}
+
+func makeHTTPRequest() {
+
+	var err error
+	if conn != nil {
+		conn.Close()
+	}
+
+	// make TCP connection
+	ip := net.ParseIP(server)
+	raddr := &net.TCPAddr{IP: ip, Port: 80}
+	laddr := &net.TCPAddr{Port: 8080}
+
+	message("\r\n---------------\r\nDialing TCP connection")
+	conn, err = net.DialTCP("tcp", laddr, raddr)
+	for ; err != nil; conn, err = net.DialTCP("tcp", laddr, raddr) {
+		message("connection failed: " + err.Error())
+		time.Sleep(5 * time.Second)
+	}
+	println("Connected!\r")
+
+	print("Sending HTTP request...")
+	fmt.Fprintln(conn, "GET / HTTP/1.1")
+	fmt.Fprintln(conn, "Host:", server)
+	fmt.Fprintln(conn, "User-Agent: TinyGo/0.10.0")
+	fmt.Fprintln(conn, "Connection: close")
+	fmt.Fprintln(conn)
+	println("Sent!\r\n\r")
+
+	lastRequestTime = time.Now()
+}
+
+func readLine(conn *net.TCPSerialConn) string {
+	println("Attempting to read...\r")
+	b := buf[:]
+	for expiry := time.Now().Unix() + 10; time.Now().Unix() > expiry; {
+		if n, err := conn.Read(b); n > 0 && err == nil {
+			return string(b[0:n])
+		}
+	}
+	return ""
+}
+
+// connect to access point
+func connectToAP() {
+	time.Sleep(2 * time.Second)
+	message("Connecting to " + ssid)
+	adaptor.SetPassphrase(ssid, pass)
+	for st, _ := adaptor.GetConnectionStatus(); st != wifinina.StatusConnected; {
+		message("Connection status: " + st.String())
+		time.Sleep(1 * time.Second)
+		st, _ = adaptor.GetConnectionStatus()
+	}
+	message("Connected.")
+	time.Sleep(2 * time.Second)
+	ip, _, _, err := adaptor.GetIP()
+	for ; err != nil; ip, _, _, err = adaptor.GetIP() {
+		message(err.Error())
+		time.Sleep(1 * time.Second)
+	}
+	message(ip.String())
+}
+
+func message(msg string) {
+	println(msg, "\r")
+}