ESP8266 Community Forum

- Thu Feb 18, 2016 1:51 am #41337 Hi all,

I don't know if this is the right board, so feel free to move it wherever it is more appropriate.

I use the ESP-ADC module from In-Circuit with Arduino IDE 1.6.5 and the latest ESP8266 libraries from github (downloaded on 02.02.2016).

The ESP is in Station mode and connects to an Accesspoint. I use my desktop PC to request webpages from the ESP. Don't know if this matters, but since I don't know, I prefer to mention it

The issue I have is that while processing the request from the browser the data transfer from the ESP is interrupted.
If I re-request the page in the browser all is well again, until the next transfer error -8....
I configured the ESP to output debug info on Serial1 and what I see there is:

:wr
:er -8 2108 1
:ww
:wr !_pcb
:wr !_pcb
:wr !_pcb
:ur 1
WS:dis
:del
Client disconnected
ip:192.168.0.100,mask:255.255.255.0,gw:192.168.0.254
wifi evt: 3

A relatively small example to recreate this behaviour (on my hardware):

Code: Select all#include <ESP8266WiFi.h>
#include <WiFiUdp.h>

// WiFi connection
char Receive_ssid[33] = "TP-LINK_791EC4";
char Receive_password[65] = "C2791EC4";

unsigned long ulReqcount;       // how often has a valid page been requested
unsigned long ulReconncount;    // how often did we connect to WiFi

int WiFiStatus = WL_IDLE_STATUS;

// storage for Measurements; keep some mem free; allocate remainder
#define KEEP_MEM_FREE 10240

// Create an instance of the server on Port 80
WiFiServer server(80);

// needed to avoid link error on ram check
extern "C"
{ 
  #include "user_interface.h"
}

/////////////////////
// the setup routine
/////////////////////
void setup()
{
  // setup globals
  ulReqcount = 0;
  ulReconncount = 0;

  // start serial
  Serial.begin(115200);
  Serial.println("  ");
  Serial.println("Webserver-Test");

  WiFi.mode(WIFI_STA);
  WiFiStart(Receive_ssid, Receive_password);

  Serial1.begin(115200);
  Serial.setDebugOutput(true);
}

///////////////////
// (re-)start WiFi
///////////////////
void WiFiStart(char* ssid, char* password)
{
  unsigned int uiTimeOut = 0;
  ulReconncount++;

  // Connect to WiFi network
  Serial.println();
  Serial.print("Connecting to ");
  Serial.print(ssid);
  Serial.print(" with password ");
  Serial.println(password);

  WiFi.begin((const char*)ssid, (const char*)password);

  while (WiFiStatus != WL_CONNECTED)
  {
    WiFiStatus = WiFi.status();
    delay(500);
    Serial.print(".");
    uiTimeOut++;
    if(uiTimeOut == 20)
    {     
      Serial.println("retry");
      WiFi.begin((const char*)ssid, (const char*)password);
    }
    if(uiTimeOut == 40)
    {     
      break;
    }
  }
  if(uiTimeOut >= 40)
  {   
    Serial.println("Could not establish connection!");
    switch (WiFiStatus)
    {
      case WL_IDLE_STATUS:
      {
        Serial.println("WL_IDLE_STATUS");
        break;
      }
      case WL_CONNECTED:
      {
        Serial.println("WL_CONNECTED");
        break;
      }
      case WL_NO_SHIELD:
      {
        Serial.println("WL_NO_SHIELD");
        break;
      }
      case WL_CONNECT_FAILED:
      {
        Serial.println("WL_CONNECT_FAILED");
        break;
      }
      case WL_NO_SSID_AVAIL:
      {
        Serial.println("WL_NO_SSID_AVAIL");
        break;
      }
      case WL_SCAN_COMPLETED:
      {
        Serial.println("WL_SCAN_COMPLETED");
        break;
      }
      case WL_CONNECTION_LOST:
      {
        Serial.println("WL_CONNECTION_LOST");
        break;
      }
      case WL_DISCONNECTED:
      {
        Serial.println("WL_DISCONNECTED");
        break;
      }
      default:
      {
        Serial.println("No idea what went wrong...");
      }
    }


    return;
  }
  Serial.println();
  Serial.println("WiFi connected");

  delay(500);
  // Start the server
  server.begin();
  Serial.println("Server started");

  // Print the IP address
  Serial.print("IP: ");
  Serial.println(WiFi.localIP());
}


//////////////////////////
// create HTTP 1.1 header
//////////////////////////
String MakeHTTPHeader(unsigned long ulLength)
{
  String sHeader;

  sHeader  = F("HTTP/1.1 200 OK\r\nContent-Length: ");
  sHeader += ulLength;
  sHeader += F("\r\nContent-Type: text/html\r\nConnection: close\r\n\r\n"); 

  return (sHeader);
}


////////////////////
// make html footer
////////////////////
String MakeHTTPFooter()
{
  String sResponse;

  sResponse  = F("\r\n<div style=\"font-size:x-small\">");
  sResponse += F("\r\n\t<BR>Aufrufz&auml;hler = ");
  sResponse += ulReqcount;
  sResponse += F("\r\n\t<BR>Verbindungsz&auml;hler = ");
  sResponse += ulReconncount;
  sResponse += F("\r\n\t<BR>Freies RAM = ");
  sResponse += (uint32_t)system_get_free_heap_size();
  sResponse += F("\r\n</div>\r\n</body>\r\n</html>");

  return (sResponse);
}


/////////////
// main look
/////////////
void loop()
{
  delay(50);

  //////////////////////////////
  // check if WLAN is connected
  //////////////////////////////

  if(WiFi.status() != WL_CONNECTED)
  {
    Serial.println("restart server if not connected");
    WiFiStart(Receive_ssid, Receive_password);
  }

  ///////////////////////////////////
  // Check if a client has connected
  ///////////////////////////////////
  WiFiClient client = server.available();
  if (!client)
  {
    return;
  }

  // Wait until the client sends some data
  Serial.println("new client");
  unsigned long ultimeout = millis() + 250;
  while (!client.available() && (millis() < ultimeout) )
  {
    delay(1);
  }

  if (millis() > ultimeout)
  {
    Serial.println("client connection time-out!");
    return;
  }

  /////////////////////////////////////
  // Read the first line of the request
  /////////////////////////////////////
  String sRequest = client.readStringUntil('\r');
  Serial.println(sRequest);
  client.flush();

  // stop client, if request is empty
  if (sRequest == "")
  {
    Serial.println("empty request! - stopping client");
    client.stop();
    return;
  }

  // get path; end of path is either space or ?
  // Syntax is e.g. GET /?show=1234 HTTP/1.1
  String sPath = "", sParam = "", sCmd = "";
  String sGetstart = "GET ";
  int iStart, iEndSpace, iEndQuest;
  iStart = sRequest.indexOf(sGetstart);
  if (iStart >= 0)
  {
    iStart += +sGetstart.length();
    iEndSpace = sRequest.indexOf(" ", iStart);
    iEndQuest = sRequest.indexOf("?", iStart);

    // are there parameters?
    if (iEndSpace > 0)
    {
      if (iEndQuest > 0)
      {
        // there are parameters
        sPath  = sRequest.substring(iStart, iEndQuest);
        sParam = sRequest.substring(iEndQuest, iEndSpace);
      }
      else
      {
        // NO parameters
        sPath  = sRequest.substring(iStart, iEndSpace);
      }
    }
  }


  ///////////////////////////
  // format the html response
  ///////////////////////////
  String sResponse, sResponse2, sHeader;


  if (sPath == "/")
    ////////////////////////////////////
    // format the html page for /tabelle
    ////////////////////////////////////
  {
    ulReqcount++;
    sResponse  = F("<!DOCTYPE HTML>");
    sResponse += F("\r\n<html>\r\n<head>\r\n<meta http-equiv=\"content-type\" content=\"text/html; charset=utf-8\">");
    sResponse += F("\r\n\t<meta http-equiv=\"refresh\" content=\"2; url=/\">");
    sResponse += F("\r\n\t<style>");
    sResponse += F("\r\n\t\tbody {background-color: #dfdfdf;}");
    sResponse += F("\r\n\t\tfont {color: #000000;}");
    sResponse += F("\r\n\t\ttable {font-size: large; width:100%;}");
    sResponse += F("\r\n\t\ttable, th, td {border: 2px solid black; border-collapse: collapse;}");
    sResponse += F("\r\n\t\tth, td {padding: 5px;}");
    sResponse += F("\r\n\t\tth {text-align: left;}");
    sResponse += F("\r\n\t</style>\r\n<title>Test</title>\r\n</head>\r\n<body>");
    sResponse += F("\r\n<h1>Testdata</h1>");

    sResponse += "\r\n<table>";
    sResponse += "\r\n\t<tbody><tr><th>#</th><th>Time</th><th>Calibration used</th><th>Sesnor 1</th><th>Sensor2</th></tr>";
    sResponse += "\r\n\t<tr><td>1</td><td>04.02.2016 09:40:12</td><td>Standard</td><td>25,12</td><td>10,60</td></tr>";
    sResponse += "\r\n\t<tr><td>1</td><td>04.02.2016 09:40:14</td><td>Standard</td><td>25,14</td><td>10,67</td></tr>";
    sResponse += "\r\n\t<tr><td>1</td><td>04.02.2016 09:40:16</td><td>Standard</td><td>25,09</td><td>10,58</td></tr>";
    sResponse += "\r\n\t<tr><td>1</td><td>04.02.2016 09:40:18</td><td>Standard</td><td>25,11</td><td>10,62</td></tr>";
    sResponse += "\r\n\t<tr><td>1</td><td>04.02.2016 09:40:20</td><td>Standard</td><td>25,12</td><td>10,61</td></tr>";
    sResponse += "\r\n\t<tr><td>1</td><td>04.02.2016 09:40:22</td><td>Standard</td><td>25,15</td><td>10,70</td></tr>";
    sResponse += "\r\n\t<tr><td>1</td><td>04.02.2016 09:40:24</td><td>Standard</td><td>25,10</td><td>10,63</td></tr>";
    sResponse += "\r\n\t<tr><td>1</td><td>04.02.2016 09:40:26</td><td>Standard</td><td>25,13</td><td>10,67</td></tr>";
    sResponse += "\r\n</tbody></table>";

    sResponse2 = MakeHTTPFooter().c_str();

    // Send the response to the client - delete strings after use to keep mem low

    client.print(MakeHTTPHeader(sResponse.length() + sResponse2.length()));
    client.print(sResponse);
    sResponse = "";
    client.print(sResponse2);     
    sResponse2 = "";
  }

  else
    ////////////////////////////
    // 404 for non-matching path
    ////////////////////////////
  {
    sResponse = "<html><head><title>404 Not Found</title></head><body><h1>Not Found</h1><p>The requested URL was not found on this server.</p></body></html>";

    sHeader  = F("HTTP/1.1 404 Not found\r\nContent-Length: ");
    sHeader += sResponse.length();
    sHeader += F("\r\nContent-Type: text/html\r\nConnection: close\r\n\r\n");

    // Send the response to the client
    client.print(sHeader);
    client.print(sResponse);
  }

  // and stop the client
  client.stop();
  Serial.println("Client disconnected");
  delay(50);
}

I tried several things, also modified the code to use ESP8266WebServer and the corresponding server.send() commands but that didn't cure it.
Most notable difference is that I don't get the

:wr !_pcb

debug output any more.

I found out that it has to do with the tcp_output( _pcb ) function in ClientContext.h (regardless which function is used to stream out data) but I have absolutely no idea how I could debug any deeper into the libraries.
My knowledge about Arduino environment and WiFi is very limited.

Any help greatly appreciated