espat: add support for esp8266/esp32 Wifi adaptor AT command set with net-compatible UDP support

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

espat/commands.go

@@ -0,0 +1,104 @@
+package espat
+
+// Basic AT commands
+const (
+	// Test that the device is working.
+	Test = ""
+
+	// Restart module
+	Restart = "+RST"
+
+	// Version show info about the current software version.
+	Version = "+GMR"
+
+	// Enter deep-sleep mode
+	Sleep = "+GSLP"
+
+	// Configure echo.
+	EchoConfig = "E"
+
+	// EchoConfigOn
+	EchoConfigOn = EchoConfig + "1"
+
+	// EchoConfigOff
+	EchoConfigOff = EchoConfig + "0"
+
+	// Configure UART
+	UARTConfig = "+UART"
+)
+
+// WiFi commands.
+const (
+	// WiFi mode (sta/AP/sta+AP)
+	WifiMode = "+CWMODE"
+
+	// Connect to an access point.
+	ConnectAP = "+CWJAP"
+
+	// List available AP's
+	ListAP = "+CWLAP"
+
+	// Disconnect from the current AP
+	Disconnect = "+CWQAP"
+
+	// Set softAP configuration. This also activates the ESP8266/ESP32 to act as an access point.
+	// The settings will not be saved in flash memory, so they will be forgotten on next reset.
+	SoftAPConfigCurrent = "+CWSAP_CUR"
+
+	// Set softAP configuration as saved in flash. This also activates the ESP8266/ESP32 to act as an
+	// access point. The settings will be saved in flash memory, so they will be used on next reset.
+	SoftAPConfigFlash = "+CWSAP_DEF"
+
+	// List station IP's connected to softAP
+	ListConnectedIP = "+CWLIF"
+
+	// Enable/disable DHCP
+	DHCPConfig = "+CWDHCP"
+
+	// Set MAC address of station
+	SetStationMACAddress = "+CIPSTAMAC"
+
+	// Set MAC address of softAP
+	SetAPMACAddress = "+CIPAPMAC"
+
+	// Set IP address of ESP8266/ESP32 station
+	SetStationIP = "+CIPSTA"
+
+	// Set IP address of ESP8266/ESP32 when acting as access point.
+	// The IP address will not be saved in flash memory, so it will be forgotten on next reset.
+	SetSoftAPIPCurrent = "+CIPAP_CUR"
+
+	// Set IP address of ESP8266/ESP32 when acting as access point.
+	// The IP address will be saved in flash memory, so they will be used on next reset.
+	SetSoftAPIPFlash = "+CIPAP_DEF"
+)
+
+// TCP/IP commands
+const (
+	// Get connection status
+	TCPStatus = "+CIPSTATUS"
+
+	// Establish TCP connection or register UDP port
+	TCPConnect = "+CIPSTART"
+
+	// Send Data
+	TCPSend = "+CIPSEND"
+
+	// Close TCP/UDP connection
+	TCPClose = "+CIPCLOSE"
+
+	// Get local IP address
+	GetLocalIP = "+CIFSR"
+
+	// Set multiple connections mode
+	TCPMultiple = "+CIPMUX"
+
+	// Configure as server
+	ServerConfig = "+CIPSERVER"
+
+	// Set transmission mode
+	TransmissionMode = "+CIPMODE"
+
+	// Set timeout when ESP8266/ESP32 runs as TCP server
+	SetServerTimeout = "+CIPSTO"
+)

espat/espat.go

@@ -0,0 +1,252 @@
+// Package espat implements TCP/UDP wireless communication over serial
+// with a separate ESP8266 or ESP32 board using the Espressif AT command set
+// across a UART interface.
+//
+// In order to use this driver, the ESP8266/ESP32 must be flashed with firmware
+// supporting the AT command set. Many ESP8266/ESP32 chips already have this firmware
+// installed by default. You will need to install this firmware if you have an
+// ESP8266 that has been flashed with NodeMCU (Lua) or Arduino firmware.
+//
+// AT Command Core repository:
+// https://github.com/espressif/esp32-at
+//
+// Datasheet:
+// https://www.espressif.com/sites/default/files/documentation/0a-esp8266ex_datasheet_en.pdf
+//
+// AT command set:
+// https://www.espressif.com/sites/default/files/documentation/4a-esp8266_at_instruction_set_en.pdf
+//
+package espat
+
+import (
+	"machine"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// Device wraps UART connection to the ESP8266/ESP32.
+type Device struct {
+	bus machine.UART
+
+	// command responses that come back from the ESP8266/ESP32
+	response []byte
+
+	// data received from a TCP/UDP connection forwarded by the ESP8266/ESP32
+	socketdata []byte
+}
+
+// New returns a new espat driver. Pass in a fully configured UART bus.
+func New(b machine.UART) *Device {
+	return &Device{bus: b, response: make([]byte, 512), socketdata: make([]byte, 0, 1024)}
+}
+
+// Configure sets up the device for communication.
+func (d Device) Configure() {
+}
+
+// Connected checks if there is communication with the ESP8266/ESP32.
+func (d *Device) Connected() bool {
+	d.Execute(Test)
+
+	// handle response here, should include "OK"
+	r := d.Response()
+	if strings.Contains(string(r), "OK") {
+		return true
+	}
+	return false
+}
+
+// Write raw bytes to the UART.
+func (d *Device) Write(b []byte) (n int, err error) {
+	return d.bus.Write(b)
+}
+
+// Read raw bytes from the UART.
+func (d *Device) Read(b []byte) (n int, err error) {
+	return d.bus.Read(b)
+}
+
+// how long in milliseconds to pause after sending AT commands
+const pause = 100
+
+// Execute sends an AT command to the ESP8266/ESP32.
+func (d Device) Execute(cmd string) error {
+	_, err := d.Write([]byte("AT" + cmd + "\r\n"))
+	return err
+}
+
+// Query sends an AT command to the ESP8266/ESP32 that returns the
+// current value for some configuration parameter.
+func (d Device) Query(cmd string) (string, error) {
+	_, err := d.Write([]byte("AT" + cmd + "?\r\n"))
+	return "", err
+}
+
+// Set sends an AT command with params to the ESP8266/ESP32 for a
+// configuration value to be set.
+func (d Device) Set(cmd, params string) error {
+	_, err := d.Write([]byte("AT" + cmd + "=" + params + "\r\n"))
+	return err
+}
+
+// Version returns the ESP8266/ESP32 firmware version info.
+func (d Device) Version() []byte {
+	d.Execute(Version)
+	return d.Response()
+}
+
+// Echo sets the ESP8266/ESP32 echo setting.
+func (d Device) Echo(set bool) {
+	if set {
+		d.Execute(EchoConfigOn)
+	} else {
+		d.Execute(EchoConfigOff)
+	}
+	// TODO: check for success
+	d.Response()
+}
+
+// Reset restarts the ESP8266/ESP32 firmware. Due to how the baud rate changes,
+// this messes up communication with the ESP8266/ESP32 module. So make sure you know
+// what you are doing when you call this.
+func (d Device) Reset() {
+	d.Execute(Restart)
+	d.Response()
+}
+
+// ReadSocket returns the data that has already been read in from the responses.
+func (d *Device) ReadSocket(b []byte) (n int, err error) {
+	// make sure no data in buffer
+	d.Response()
+
+	count := len(b)
+	if len(b) >= len(d.socketdata) {
+		// copy it all, then clear socket data
+		count = len(d.socketdata)
+		copy(b, d.socketdata[:count])
+		d.socketdata = d.socketdata[:0]
+	} else {
+		// copy all we can, then keep the remaining socket data around
+		copy(b, d.socketdata[:count])
+		copy(d.socketdata, d.socketdata[count:])
+		d.socketdata = d.socketdata[:len(d.socketdata)-count]
+	}
+
+	return count, nil
+}
+
+// Response gets the next response bytes from the ESP8266/ESP32.
+func (d *Device) Response() []byte {
+	var i, retries int
+
+	header := make([]byte, 2)
+	for {
+		for d.bus.Buffered() > 0 {
+			// get the first 2 bytes
+			header[0], _ = d.bus.ReadByte()
+			header[1], _ = d.bus.ReadByte()
+
+			if d.isLeadingCRLF(header) {
+				// skip it
+				header[0], _ = d.bus.ReadByte()
+				header[1], _ = d.bus.ReadByte()
+			}
+
+			if d.isIPD(header) {
+				// is socket data packet
+				d.parseIPD()
+			} else {
+				// no, so put into response
+				d.response[i] = header[0]
+				i++
+				d.response[i] = header[1]
+				i++
+			}
+
+			// read the rest of normal command response
+			for d.bus.Buffered() > 0 {
+				data, err := d.bus.ReadByte()
+				if err != nil {
+					return nil
+				}
+				d.response[i] = data
+				i++
+			}
+		}
+		retries++
+		if retries > 2 {
+			break
+		}
+
+		// pause to make sure is no more data to be read
+		time.Sleep(10 * time.Millisecond)
+	}
+	return d.response[:i]
+}
+
+func (d *Device) isLeadingCRLF(b []byte) bool {
+	if len(b) < 2 {
+		return false
+	}
+	if b[0] == 13 && b[1] == 10 {
+		return true
+	}
+	return false
+}
+
+func (d *Device) isIPD(b []byte) bool {
+	if len(b) < 2 {
+		return false
+	}
+	if b[0] == '+' && b[1] == 'I' {
+		return true
+	}
+	return false
+}
+
+func (d *Device) parseIPD() bool {
+	data, _ := d.bus.ReadByte()
+	if data != 'P' {
+		// error
+		return false
+	}
+	data, _ = d.bus.ReadByte()
+	if data != 'D' {
+		// error
+		return false
+	}
+	data, _ = d.bus.ReadByte()
+	if data != ',' {
+		// error
+		return false
+	}
+
+	// get the expected data length
+	// skip remaining header up to the ":"
+	buf := []byte{}
+	data, _ = d.bus.ReadByte()
+	for data != ':' {
+		// put into the buffer with int value here
+		buf = append(buf, data)
+
+		// read next value
+		data, _ = d.bus.ReadByte()
+	}
+
+	val := string(buf)
+	count, err := strconv.Atoi(val)
+	if err != nil {
+		// not expected data here. what to do?
+		return false
+	}
+
+	// load up the socket data
+	// only read the expected amount of data
+	for m := 0; m < count; m++ {
+		data, _ = d.bus.ReadByte()
+		d.socketdata = append(d.socketdata, data)
+	}
+
+	return true
+}

espat/net.go

@@ -0,0 +1,143 @@
+package espat
+
+import (
+	"strconv"
+	"time"
+)
+
+// DialUDP makes a UDP network connection. raadr is the port that the messages will
+// be sent to, and laddr is the port that will be listened to in order to
+// receive incoming messages.
+func (d Device) DialUDP(network string, laddr, raddr *UDPAddr) (*SerialConn, error) {
+	addr := raddr.IP.String()
+	sendport := strconv.Itoa(raddr.Port)
+	listenport := strconv.Itoa(laddr.Port)
+
+	// disconnect any old socket
+	d.DisconnectSocket()
+
+	// connect new socket
+	d.ConnectUDPSocket(addr, sendport, listenport)
+
+	return &SerialConn{Adaptor: &d, laddr: laddr, raddr: raddr}, nil
+}
+
+// ListenUDP listens for UDP connections on the port listed in laddr.
+func (d Device) ListenUDP(network string, laddr *UDPAddr) (*SerialConn, error) {
+	addr := "0"
+	sendport := "0"
+	listenport := strconv.Itoa(laddr.Port)
+
+	// disconnect any old socket
+	d.DisconnectSocket()
+
+	// connect new socket
+	d.ConnectUDPSocket(addr, sendport, listenport)
+
+	return &SerialConn{Adaptor: &d, laddr: laddr}, nil
+}
+
+// SerialConn is a loosely net.Conn compatible intended to support
+// TCP/UDP over serial.
+type SerialConn struct {
+	Adaptor *Device
+	laddr   *UDPAddr
+	raddr   *UDPAddr
+}
+
+// Read reads data from the connection.
+// TODO: implement the full method functionality:
+// Read can be made to time out and return an Error with Timeout() == true
+// after a fixed time limit; see SetDeadline and SetReadDeadline.
+func (c *SerialConn) Read(b []byte) (n int, err error) {
+	// read only the data that has been received via "+IPD" socket
+	return c.Adaptor.ReadSocket(b)
+}
+
+// Write writes data to the connection.
+// TODO: implement the full method functionality for timeouts.
+// Write can be made to time out and return an Error with Timeout() == true
+// after a fixed time limit; see SetDeadline and SetWriteDeadline.
+func (c *SerialConn) Write(b []byte) (n int, err error) {
+	// specify that is a data transfer to the
+	// currently open socket, not commands to the ESP8266/ESP32.
+	c.Adaptor.StartSocketSend(len(b))
+	return c.Adaptor.Write(b)
+}
+
+// Close closes the connection.
+// Currently only supports a single Read or Write operations without blocking.
+func (c *SerialConn) Close() error {
+	c.Adaptor.DisconnectSocket()
+	return nil
+}
+
+// LocalAddr returns the local network address.
+func (c *SerialConn) LocalAddr() UDPAddr {
+	return *c.laddr
+}
+
+// RemoteAddr returns the remote network address.
+func (c *SerialConn) RemoteAddr() UDPAddr {
+	return *c.laddr
+}
+
+// SetDeadline sets the read and write deadlines associated
+// with the connection. It is equivalent to calling both
+// SetReadDeadline and SetWriteDeadline.
+//
+// A deadline is an absolute time after which I/O operations
+// fail with a timeout (see type Error) instead of
+// blocking. The deadline applies to all future and pending
+// I/O, not just the immediately following call to Read or
+// Write. After a deadline has been exceeded, the connection
+// can be refreshed by setting a deadline in the future.
+//
+// An idle timeout can be implemented by repeatedly extending
+// the deadline after successful Read or Write calls.
+//
+// A zero value for t means I/O operations will not time out.
+func (c *SerialConn) SetDeadline(t time.Time) error {
+	return nil
+}
+
+// SetReadDeadline sets the deadline for future Read calls
+// and any currently-blocked Read call.
+// A zero value for t means Read will not time out.
+func (c *SerialConn) SetReadDeadline(t time.Time) error {
+	return nil
+}
+
+// SetWriteDeadline sets the deadline for future Write calls
+// and any currently-blocked Write call.
+// Even if write times out, it may return n > 0, indicating that
+// some of the data was successfully written.
+// A zero value for t means Write will not time out.
+func (c *SerialConn) SetWriteDeadline(t time.Time) error {
+	return nil
+}
+
+// The following definitions are here to support a Golang standard package
+// net-compatible interface for IP until TinyGo can compile the net package.
+
+// IP is an IP address. Unlike the standard implementation, it is only
+// a buffer of bytes that contains the string form of the IP address, not the
+// full byte format used by the Go standard .
+type IP []byte
+
+// UDPAddr here to serve as compatible type. until TinyGo can compile the net package.
+type UDPAddr struct {
+	IP   IP
+	Port int
+	Zone string // IPv6 scoped addressing zone; added in Go 1.1
+}
+
+// ParseIP parses s as an IP address, returning the result.
+func ParseIP(s string) IP {
+	return IP([]byte(s))
+}
+
+// String returns the string form of the IP address ip.
+func (ip IP) String() string {
+	return string(ip)
+}

espat/tcp.go

@@ -0,0 +1,97 @@
+package espat
+
+import (
+	"strconv"
+	"time"
+)
+
+const (
+	TCPMuxSingle   = 0
+	TCPMuxMultiple = 1
+
+	TCPTransferModeNormal      = 0
+	TCPTransferModeUnvarnished = 1
+)
+
+// ConnectTCPSocket creates a new TCP socket connection for the ESP8266/ESP32.
+// Currently only supports single connection mode.
+func (d *Device) ConnectTCPSocket(addr, port string) error {
+	protocol := "TCP"
+	val := "\"" + protocol + "\",\"" + addr + "\"," + port
+	d.Set(TCPConnect, val)
+	time.Sleep(100 * time.Millisecond)
+	d.Response()
+	return nil
+}
+
+// ConnectUDPSocket creates a new UDP connection for the ESP8266/ESP32.
+func (d *Device) ConnectUDPSocket(addr, sendport, listenport string) error {
+	protocol := "UDP"
+	val := "\"" + protocol + "\",\"" + addr + "\"," + sendport + "," + listenport + ",2"
+	d.Set(TCPConnect, val)
+	time.Sleep(pause * time.Millisecond)
+	d.Response()
+	return nil
+}
+
+// DisconnectSocket disconnects the ESP8266/ESP32 from the current TCP/UDP connection.
+func (d *Device) DisconnectSocket() error {
+	d.Execute(TCPClose)
+	time.Sleep(pause * time.Millisecond)
+	d.Response()
+	return nil
+}
+
+// SetMux sets the ESP8266/ESP32 current client TCP/UDP configuration for concurrent connections
+// either single TCPMuxSingle or multiple TCPMuxMultiple (up to 4).
+func (d *Device) SetMux(mode int) error {
+	val := strconv.Itoa(mode)
+	d.Set(TCPMultiple, val)
+	time.Sleep(pause * time.Millisecond)
+	d.Response()
+	return nil
+}
+
+// GetMux returns the ESP8266/ESP32 current client TCP/UDP configuration for concurrent connections.
+func (d *Device) GetMux() ([]byte, error) {
+	d.Query(TCPMultiple)
+	return d.Response(), nil
+}
+
+// SetTCPTransferMode sets the ESP8266/ESP32 current client TCP/UDP transfer mode.
+// Either TCPTransferModeNormal or TCPTransferModeUnvarnished.
+func (d *Device) SetTCPTransferMode(mode int) error {
+	val := strconv.Itoa(mode)
+	d.Set(TransmissionMode, val)
+	time.Sleep(pause * time.Millisecond)
+	d.Response()
+	return nil
+}
+
+// GetTCPTransferMode returns the ESP8266/ESP32 current client TCP/UDP transfer mode.
+func (d *Device) GetTCPTransferMode() []byte {
+	d.Query(TransmissionMode)
+	return d.Response()
+}
+
+// StartSocketSend gets the ESP8266/ESP32 ready to receive TCP/UDP socket data.
+func (d *Device) StartSocketSend(size int) error {
+	val := strconv.Itoa(size)
+	d.Set(TCPSend, val)
+
+	// TODO: wait until ">" is received, which indicates
+	// ready to receive data
+	d.Response()
+	return nil
+}
+
+// EndSocketSend tell the ESP8266/ESP32 the TCP/UDP socket data sending is complete,
+// and to return to command mode. This is only used in "unvarnished" raw mode.
+func (d *Device) EndSocketSend() error {
+	d.Write([]byte("+++"))
+
+	// TODO: wait until ">" is received, which indicates
+	// ready to receive data
+	d.Response()
+	return nil
+}

espat/wifi.go

@@ -0,0 +1,154 @@
+package espat
+
+import (
+	"strconv"
+	"time"
+)
+
+const (
+	WifiModeClient = 1
+	WifiModeAP     = 2
+	WifiModeDual   = 3
+
+	WifiAPSecurityOpen         = 1
+	WifiAPSecurityWPA_PSK      = 2
+	WifiAPSecurityWPA2_PSK     = 3
+	WifiAPSecurityWPA_WPA2_PSK = 4
+)
+
+// GetWifiMode returns the ESP8266/ESP32 wifi mode.
+func (d *Device) GetWifiMode() []byte {
+	d.Query(WifiMode)
+	return d.Response()
+}
+
+// SetWifiMode sets the ESP8266/ESP32 wifi mode.
+func (d *Device) SetWifiMode(mode int) error {
+	val := strconv.Itoa(mode)
+	d.Set(WifiMode, val)
+	time.Sleep(pause * time.Millisecond)
+	d.Response()
+	return nil
+}
+
+// Wifi Client
+
+// GetConnectedAP returns the ESP8266/ESP32 is currently connected to as a client.
+func (d *Device) GetConnectedAP() []byte {
+	d.Query(ConnectAP)
+	return d.Response()
+}
+
+// ConnectToAP connects the ESP8266/ESP32 to an access point.
+// ws is the number of seconds to wait for connection.
+func (d *Device) ConnectToAP(ssid, pwd string, ws int) error {
+	val := "\"" + ssid + "\",\"" + pwd + "\""
+	d.Set(ConnectAP, val)
+	// TODO: a better way to wait for connect and check for up to ws seconds.
+	time.Sleep(time.Duration(ws) * time.Second)
+	d.Response()
+	return nil
+}
+
+// DisconnectFromAP disconnects the ESP8266/ESP32 from the current access point.
+func (d *Device) DisconnectFromAP() error {
+	d.Execute(Disconnect)
+	time.Sleep(1000 * time.Millisecond)
+	d.Response()
+	return nil
+}
+
+// GetClientIP returns the ESP8266/ESP32 current client IP addess when connected to an Access Point.
+func (d *Device) GetClientIP() string {
+	d.Query(SetStationIP)
+	return string(d.Response())
+}
+
+// SetClientIP sets the ESP8266/ESP32 current client IP addess when connected to an Access Point.
+func (d *Device) SetClientIP(ipaddr string) []byte {
+	val := "\"" + ipaddr + "\""
+	d.Set(ConnectAP, val)
+	time.Sleep(500 * time.Millisecond)
+	d.Response()
+	return nil
+}
+
+// Access Point
+
+// GetAPConfig returns the ESP8266/ESP32 current configuration when acting as an Access Point.
+func (d *Device) GetAPConfig() string {
+	d.Query(SoftAPConfigCurrent)
+	return string(d.Response())
+}
+
+// SetAPConfig sets the ESP8266/ESP32 current configuration when acting as an Access Point.
+// ch indicates which radiochannel to use. security should be one of the const values
+// such as WifiAPSecurityOpen etc.
+func (d *Device) SetAPConfig(ssid, pwd string, ch, security int) error {
+	chval := strconv.Itoa(ch)
+	ecnval := strconv.Itoa(security)
+	val := "\"" + ssid + "\",\"" + pwd + "\"," + chval + "," + ecnval
+	d.Set(SoftAPConfigCurrent, val)
+	time.Sleep(1000 * time.Millisecond)
+	d.Response()
+	return nil
+}
+
+// GetAPClients returns the ESP8266/ESP32 current clients when acting as an Access Point.
+func (d *Device) GetAPClients() string {
+	d.Query(ListConnectedIP)
+	return string(d.Response())
+}
+
+// GetAPIP returns the ESP8266/ESP32 current IP addess when configured as an Access Point.
+func (d *Device) GetAPIP() string {
+	d.Query(SetSoftAPIPCurrent)
+	return string(d.Response())
+}
+
+// SetAPIP sets the ESP8266/ESP32 current IP addess when configured as an Access Point.
+func (d *Device) SetAPIP(ipaddr string) error {
+	val := "\"" + ipaddr + "\""
+	d.Set(SetSoftAPIPCurrent, val)
+	time.Sleep(500 * time.Millisecond)
+	d.Response()
+	return nil
+}
+
+// GetAPConfigFlash returns the ESP8266/ESP32 current configuration acting as an Access Point
+// from flash storage. These settings are those used after a reset.
+func (d *Device) GetAPConfigFlash() string {
+	d.Query(SoftAPConfigFlash)
+	return string(d.Response())
+}
+
+// SetAPConfigFlash sets the ESP8266/ESP32 current configuration acting as an Access Point,
+// and saves them to flash storage. These settings will be used after a reset.
+// ch indicates which radiochannel to use. security should be one of the const values
+// such as WifiAPSecurityOpen etc.
+func (d *Device) SetAPConfigFlash(ssid, pwd string, ch, security int) error {
+	chval := strconv.Itoa(ch)
+	ecnval := strconv.Itoa(security)
+	val := "\"" + ssid + "\",\"" + pwd + "\"," + chval + "," + ecnval
+	d.Set(SoftAPConfigFlash, val)
+	time.Sleep(1000 * time.Millisecond)
+	d.Response()
+	return nil
+}
+
+// GetAPIPFlash returns the ESP8266/ESP32 IP address as saved to flash storage.
+// This is the IP address that will be used after a reset.
+func (d *Device) GetAPIPFlash() string {
+	d.Query(SetSoftAPIPFlash)
+	return string(d.Response())
+}
+
+// SetAPIPFlash sets the ESP8266/ESP32 current IP addess when configured as an Access Point.
+// The IP will be saved to flash storage, and will be used after a reset.
+func (d *Device) SetAPIPFlash(ipaddr string) error {
+	val := "\"" + ipaddr + "\""
+	d.Set(SetSoftAPIPFlash, val)
+	time.Sleep(500 * time.Millisecond)
+	d.Response()
+	return nil
+}

examples/espat/espconsole/main.go

@@ -0,0 +1,129 @@
+// This is a console to a ESP8266/ESP32 running on the device UART1.
+// Allows you to type AT commands from your computer via the microcontroller.
+//
+// In other words:
+// Your computer <--> UART0 <--> MCU <--> UART1 <--> ESP8266 <--> INTERNET
+//
+// More information on the Espressif AT command set at:
+// https://www.espressif.com/sites/default/files/documentation/4a-esp8266_at_instruction_set_en.pdf
+//
+package main
+
+import (
+	"machine"
+	"time"
+
+	"github.com/tinygo-org/drivers/espat"
+)
+
+// change actAsAP to true to act as an access point instead of connecting to one.
+const actAsAP = false
+
+// access point info
+const ssid = "YOURSSID"
+const pass = "YOURPASS"
+
+// change these to connect to a different UART or pins for the ESP8266/ESP32
+var (
+	uart       = machine.UART1
+	tx   uint8 = machine.D10
+	rx   uint8 = machine.D11
+
+	console = machine.UART0
+
+	adaptor *espat.Device
+)
+
+func main() {
+	uart.Configure(machine.UARTConfig{TX: tx, RX: rx})
+
+	// Init esp8266
+	adaptor = espat.New(uart)
+	adaptor.Configure()
+
+	// first check if connected
+	if adaptor.Connected() {
+		adaptor.Echo(false)
+		console.Write([]byte("\r\n"))
+		console.Write([]byte("ESP-AT console enabled.\r\n"))
+		console.Write([]byte("Firmware version:\r\n"))
+		console.Write(adaptor.Version())
+		console.Write([]byte("\r\n"))
+
+		if actAsAP {
+			provideAP()
+		} else {
+			connectToAP()
+		}
+
+		console.Write([]byte("Type an AT command then press enter:\r\n"))
+		prompt()
+	} else {
+		console.Write([]byte("\r\n"))
+		console.Write([]byte("Unable to connect to wifi adaptor.\r\n"))
+		return
+	}
+
+	input := make([]byte, 64)
+	i := 0
+	for {
+		if console.Buffered() > 0 {
+			data, _ := console.ReadByte()
+
+			switch data {
+			case 13:
+				// return key
+				console.Write([]byte("\r\n"))
+
+				// send command to ESP8266
+				input[i] = byte('\r')
+				input[i+1] = byte('\n')
+				adaptor.Write(input[:i+2])
+
+				// give the ESP8266 a chance to respond.
+				time.Sleep(10 * time.Millisecond)
+
+				// display response
+				console.Write(adaptor.Response())
+
+				// prompt
+				prompt()
+
+				i = 0
+				continue
+			default:
+				// just echo the character
+				console.WriteByte(data)
+				input[i] = data
+				i++
+			}
+		}
+		time.Sleep(10 * time.Millisecond)
+	}
+}
+
+func prompt() {
+	console.Write([]byte("ESPAT>"))
+}
+
+// connect to access point
+func connectToAP() {
+	console.Write([]byte("Connecting to wifi network...\r\n"))
+	adaptor.SetWifiMode(espat.WifiModeClient)
+	adaptor.ConnectToAP(ssid, pass, 10)
+	console.Write([]byte("Connected.\r\n"))
+	console.Write([]byte(adaptor.GetClientIP()))
+	console.Write([]byte("\r\n"))
+}
+
+// provide access point
+func provideAP() {
+	console.Write([]byte("Starting wifi network as access point '"))
+	console.Write([]byte(ssid))
+	console.Write([]byte("'...\r\n"))
+	adaptor.SetWifiMode(espat.WifiModeAP)
+	adaptor.SetAPConfig(ssid, pass, 7, espat.WifiAPSecurityWPA2_PSK)
+	console.Write([]byte("Ready.\r\n"))
+	console.Write([]byte(adaptor.GetAPIP()))
+	console.Write([]byte("\r\n"))
+}

examples/espat/esphub/main.go

@@ -0,0 +1,111 @@
+// This is a sensor hub that uses a ESP8266/ESP32 running on the device UART1.
+// It creates a UDP "server" you can use to get info to/from your computer via the microcontroller.
+//
+// In other words:
+// Your computer <--> UART0 <--> MCU <--> UART1 <--> ESP8266 <--> INTERNET
+//
+package main
+
+import (
+	"machine"
+	"time"
+
+	"github.com/tinygo-org/drivers/espat"
+)
+
+// change actAsAP to true to act as an access point instead of connecting to one.
+const actAsAP = false
+
+// access point info
+const ssid = "YOURSSID"
+const pass = "YOURPASS"
+
+// change these to connect to a different UART or pins for the ESP8266/ESP32
+var (
+	uart       = machine.UART1
+	tx   uint8 = machine.D10
+	rx   uint8 = machine.D11
+
+	console = machine.UART0
+
+	adaptor *espat.Device
+)
+
+func main() {
+	uart.Configure(machine.UARTConfig{TX: tx, RX: rx})
+
+	// Init esp8266
+	adaptor = espat.New(uart)
+	adaptor.Configure()
+
+	readyled := machine.GPIO{machine.LED}
+	readyled.Configure(machine.GPIOConfig{Mode: machine.GPIO_OUTPUT})
+	readyled.High()
+
+	// first check if connected
+	if adaptor.Connected() {
+		console.Write([]byte("Connected to wifi adaptor.\r\n"))
+		adaptor.Echo(false)
+
+		if actAsAP {
+			provideAP()
+		} else {
+			connectToAP()
+		}
+	} else {
+		console.Write([]byte("\r\n"))
+		console.Write([]byte("Unable to connect to wifi adaptor.\r\n"))
+		return
+	}
+
+	// now make UDP connection
+	laddr := &espat.UDPAddr{Port: 2222}
+	console.Write([]byte("Loading UDP listener...\r\n"))
+	conn, _ := adaptor.ListenUDP("UDP", laddr)
+
+	console.Write([]byte("Waiting for data...\r\n"))
+	data := make([]byte, 50)
+	blink := true
+	for {
+		n, _ := conn.Read(data)
+		if n > 0 {
+			console.Write(data[:n])
+			console.Write([]byte("\r\n"))
+			conn.Write([]byte("hello back\r\n"))
+		}
+		blink = !blink
+		if blink {
+			readyled.High()
+		} else {
+			readyled.Low()
+		}
+		time.Sleep(500 * time.Millisecond)
+	}
+
+	// Right now this code is never reached. Need a way to trigger it...
+	console.Write([]byte("Disconnecting UDP...\r\n"))
+	conn.Close()
+	console.Write([]byte("Done.\r\n"))
+}
+
+// connect to access point
+func connectToAP() {
+	console.Write([]byte("Connecting to wifi network...\r\n"))
+	adaptor.SetWifiMode(espat.WifiModeClient)
+	adaptor.ConnectToAP(ssid, pass, 10)
+	console.Write([]byte("Connected.\r\n"))
+	console.Write([]byte(adaptor.GetClientIP()))
+	console.Write([]byte("\r\n"))
+}
+
+// provide access point
+func provideAP() {
+	console.Write([]byte("Starting wifi network as access point '"))
+	console.Write([]byte(ssid))
+	console.Write([]byte("'...\r\n"))
+	adaptor.SetWifiMode(espat.WifiModeAP)
+	adaptor.SetAPConfig(ssid, pass, 7, espat.WifiAPSecurityWPA2_PSK)
+	console.Write([]byte("Ready.\r\n"))
+	console.Write([]byte(adaptor.GetAPIP()))
+	console.Write([]byte("\r\n"))
+}

examples/espat/espstation/main.go

@@ -0,0 +1,83 @@
+// This is a sensor station that uses a ESP8266 or ESP32 running on the device UART1.
+// It creates a UDP connection you can use to get info to/from your computer via the microcontroller.
+//
+// In other words:
+// Your computer <--> UART0 <--> MCU <--> UART1 <--> ESP8266
+//
+package main
+
+import (
+	"machine"
+	"time"
+
+	"github.com/tinygo-org/drivers/espat"
+)
+
+// access point info
+const ssid = "YOURSSID"
+const pass = "YOURPASS"
+
+// IP address of the listener aka "hub". Replace with your own info.
+const hubIP = "0.0.0.0"
+
+// change these to connect to a different UART or pins for the ESP8266/ESP32
+var (
+	uart       = machine.UART1
+	tx   uint8 = machine.D10
+	rx   uint8 = machine.D11
+
+	console = machine.UART0
+
+	adaptor *espat.Device
+)
+
+func main() {
+	uart.Configure(machine.UARTConfig{TX: tx, RX: rx})
+
+	// Init esp8266/esp32
+	adaptor = espat.New(uart)
+	adaptor.Configure()
+
+	// first check if connected
+	if adaptor.Connected() {
+		console.Write([]byte("Connected to wifi adaptor.\r\n"))
+		adaptor.Echo(false)
+
+		connectToAP()
+	} else {
+		console.Write([]byte("\r\n"))
+		console.Write([]byte("Unable to connect to wifi adaptor.\r\n"))
+		return
+	}
+
+	// now make UDP connection
+	ip := espat.ParseIP(hubIP)
+	raddr := &espat.UDPAddr{IP: ip, Port: 2222}
+	laddr := &espat.UDPAddr{Port: 2222}
+
+	console.Write([]byte("Dialing UDP connection...\r\n"))
+	conn, _ := adaptor.DialUDP("udp", laddr, raddr)
+
+	for {
+		// send data
+		console.Write([]byte("Sending data...\r\n"))
+		conn.Write([]byte("hello\r\n"))
+
+		time.Sleep(1000 * time.Millisecond)
+	}
+
+	// Right now this code is never reached. Need a way to trigger it...
+	console.Write([]byte("Disconnecting UDP...\r\n"))
+	conn.Close()
+	console.Write([]byte("Done.\r\n"))
+}
+
+// connect to access point
+func connectToAP() {
+	console.Write([]byte("Connecting to wifi network...\r\n"))
+	adaptor.SetWifiMode(espat.WifiModeClient)
+	adaptor.ConnectToAP(ssid, pass, 10)
+	console.Write([]byte("Connected.\r\n"))
+	console.Write([]byte(adaptor.GetClientIP()))
+	console.Write([]byte("\r\n"))
+}