Ensures ES8266 firmware version up to date

ESP8266/ESP8266.cpp

@@ -24,15 +24,27 @@ ESP8266::ESP8266(PinName tx, PinName rx, bool debug)
     _parser.debugOn(debug);
 }
 
+int ESP8266::get_firmware_version()
+{
+    _parser.send("AT+GMR");
+    int version;
+    if(_parser.recv("SDK version:%d", &version) && _parser.recv("OK")) {
+        return version;
+    } else { 
+        // Older firmware versions do not prefix the version with "SDK version: "
+        return -1;
+    }
+
+}
+
 bool ESP8266::startup(int mode)
 {
     //only 3 valid modes
     if(mode < 1 || mode > 3) {
         return false;
     }
 
-    bool success = reset()
-        && _parser.send("AT+CWMODE_CUR=%d", mode)
+    bool success = _parser.send("AT+CWMODE_CUR=%d", mode)
         && _parser.recv("OK")
         && _parser.send("AT+CIPMUX=1")
         && _parser.recv("OK");

ESP8266/ESP8266.h

@@ -27,6 +27,13 @@ class ESP8266
 public:
     ESP8266(PinName tx, PinName rx, bool debug=false);
 
+    /**
+    * Check firmware version of ESP8266
+    *
+    * @return integer firmware version or -1 if firmware query command gives outdated response
+    */
+    int get_firmware_version(void);
+
     /**
     * Startup the ESP8266
     *

ESP8266Interface.cpp

@@ -16,13 +16,17 @@
 
 #include <string.h>
 #include "ESP8266Interface.h"
+#include "mbed_debug.h"
 
 // Various timeouts for different ESP8266 operations
 #define ESP8266_CONNECT_TIMEOUT 15000
 #define ESP8266_SEND_TIMEOUT    500
 #define ESP8266_RECV_TIMEOUT    0
 #define ESP8266_MISC_TIMEOUT    500
 
+// Firmware version
+#define ESP8266_VERSION 2
+
 // ESP8266Interface implementation
 ESP8266Interface::ESP8266Interface(PinName tx, PinName rx, bool debug)
     : _esp(tx, rx, debug)
@@ -47,6 +51,20 @@ int ESP8266Interface::connect(const char *ssid, const char *pass, nsapi_security
 int ESP8266Interface::connect()
 {
     _esp.setTimeout(ESP8266_CONNECT_TIMEOUT);
+
+    if (!_esp.reset()) {
+        return NSAPI_ERROR_DEVICE_ERROR;
+    }   
+
+    _esp.setTimeout(ESP8266_MISC_TIMEOUT);
+
+    if (_esp.get_firmware_version() != ESP8266_VERSION) {
+        debug("ESP8266: ERROR: Firmware incompatible with this driver.\
+               \r\nUpdate to v%d - https://developer.mbed.org/teams/ESP8266/wiki/Firmware-Update\r\n",ESP8266_VERSION); 
+        return NSAPI_ERROR_DEVICE_ERROR;
+    }
+
+    _esp.setTimeout(ESP8266_CONNECT_TIMEOUT);
 
     if (!_esp.startup(3)) {
         return NSAPI_ERROR_DEVICE_ERROR;