ESP8266 send returns WOULD_BLOCK error when busy

components/wifi/esp8266-driver/ESP8266/ESP8266.cpp

@@ -50,6 +50,7 @@ ESP8266::ESP8266(PinName tx, PinName rx, bool debug, PinName rts, PinName cts)
       _fail(false),
       _sock_already(false),
       _closed(false),
+      _busy(false),
       _conn_status(NSAPI_STATUS_DISCONNECTED)
 {
     _serial.set_baud(ESP8266_DEFAULT_BAUD_RATE);
@@ -572,29 +573,33 @@ nsapi_error_t ESP8266::send(int id, const void *data, uint32_t amount)
         return NSAPI_ERROR_PARAMETER;
     }
 
-    //May take a second try if device is busy
-    for (unsigned i = 0; i < 2; i++) {
-        _smutex.lock();
-        set_timeout(ESP8266_SEND_TIMEOUT);
-        if (_parser.send("AT+CIPSEND=%d,%lu", id, amount)
-                && _parser.recv(">")
-                && _parser.write((char *)data, (int)amount) >= 0
-                && _parser.recv("SEND OK")) {
-            // No flow control, data overrun is possible
-            if (_serial_rts == NC) {
-                while (_parser.process_oob()); // Drain USART receive register
-            }
-            _smutex.unlock();
-            return NSAPI_ERROR_OK;
+    _smutex.lock();
+    set_timeout(ESP8266_SEND_TIMEOUT);
+    _busy = false;
+    if (_parser.send("AT+CIPSEND=%d,%lu", id, amount)
+            && _parser.recv(">")
+            && _parser.write((char *)data, (int)amount) >= 0
+            && _parser.recv("SEND OK")) {
+        // No flow control, data overrun is possible
+        if (_serial_rts == NC) {
+            while (_parser.process_oob()); // Drain USART receive register
         }
-        if (_error) {
-            _error = false;
-        }
-
+        _smutex.unlock();
+        return NSAPI_ERROR_OK;
+    }
+    if (_error) {
+        _error = false;
+    }
+    if (_busy) {
         set_timeout();
         _smutex.unlock();
+        tr_debug("returning WOULD_BLOCK");
+        return NSAPI_ERROR_WOULD_BLOCK;
     }
 
+    set_timeout();
+    _smutex.unlock();
+
     return NSAPI_ERROR_DEVICE_ERROR;
 }
 
@@ -963,6 +968,7 @@ void ESP8266::_oob_busy()
                    "ESP8266::_oob_busy() AT timeout\n");
     }
     _busy = true;
+    _parser.abort();
 }
 
 void ESP8266::_oob_tcp_data_hdlr()

components/wifi/esp8266-driver/ESP8266Interface.cpp

@@ -28,6 +28,7 @@
 #include "platform/Callback.h"
 #include "platform/mbed_debug.h"
 #include "platform/mbed_wait_api.h"
+#include "Kernel.h"
 
 #ifndef MBED_CONF_ESP8266_DEBUG
 #define MBED_CONF_ESP8266_DEBUG false
@@ -518,7 +519,16 @@ int ESP8266Interface::socket_send(void *handle, const void *data, unsigned size)
         return NSAPI_ERROR_NO_SOCKET;
     }
 
-    status = _esp.send(socket->id, data, size);
+    unsigned long int sendStartTime = rtos::Kernel::get_ms_count();
+    do {
+        status = _esp.send(socket->id, data, size);
+    } while ((sendStartTime - rtos::Kernel::get_ms_count() < 50)
+            && (status != NSAPI_ERROR_OK));
+
+    if (status == NSAPI_ERROR_WOULD_BLOCK) {
+        debug("Enqueuing the event call");
+        _global_event_queue->call_in(100, callback(this, &ESP8266Interface::event));
+    }
 
     return status != NSAPI_ERROR_OK ? status : size;
 }
@@ -720,4 +730,5 @@ void ESP8266Interface::proc_oob_evnt()
 {
         _esp.bg_process_oob(ESP8266_RECV_TIMEOUT, true);
 }
+
 #endif