File content as of revision 2:63135b94c898:

#include "mbed.h"
#include <stdio.h>
#include <string>
//using namespace std; 

DigitalOut  LedD1(LED1);
DigitalOut  LedD2(LED2);
DigitalOut  LedD3(LED3);
DigitalOut  LedD4(LED4);
AnalogIn poti1(p19);
AnalogIn poti2(p20);


//Serial wifi(P1_0, P0_20); // Bertl
Serial wifi(p9, p10);       // M0
Serial pc(USBTX, USBRX);
char recChar=0;
bool recFlag=false;

//string fromEsp8266 = "Arduino_SD041";
string fromEsp8266 = "";
string toEsp8266 = "";
string periodicMsg="";
long lastMsg = 0;
int url_decode(char *encoded_str, char *decoded_str);

 string getPoti(char potiNo) {
    char pValStr[20] = "ME-01";
    int n=-1;
    // pc.printf("Poti %c selected\r\n", potiNo);
    if (potiNo == '1')    
        n = sprintf(pValStr, "%d", poti1.read_u16()); 
    else if (potiNo == '2')
        n = sprintf(pValStr, "%d", poti2.read_u16()); 
    if (n<=0)
        sprintf(pValStr, "ME01"); 
    
    pc.printf("Wert von Poti %c: %s\r\n", potiNo, pValStr);
    //mcu.printf("_P%c:%s\r", potiNo, pValStr);
    return pValStr;
}    

// Process Requests from ESP8266
void ReadAndProcessRequests() {
    int chan,state,button;
    float Ain;
    char szAin[20],szT[200];
    string poti;
    
//    while(1) {
        //char inChar = 'A';            // get the new byte
        //if (inChar != '\n') {
        //    fromEsp8266 += inChar;                         // add it to receive string
        //}
        //else 
   // while(wifi.readable()) {
    //    char inChar = (char)wifi.getc();            // get the new byte
    //    if (inChar != '\n') {
    //        fromEsp8266 += inChar;                         // add it to receive string
    //    }
                                      // process string if end of line
             if(fromEsp8266.substr(0,8)=="Arduino_") {   // Valid command from ESP8266?
                if(fromEsp8266.substr(8,2) == "SM") {  // Set Digital if true
                    // --- Build Reply String -----------------------------------------------
                    toEsp8266 = "Echoing your message: ";
                    toEsp8266 += fromEsp8266.substr(10,50); 
                    wifi.printf("%s\n", toEsp8266); 
                    // ---- Set Periodic Message String -------------------------------------
                    url_decode((char *)toEsp8266.c_str(), (char *)szT );
                    periodicMsg = szT;
                }
                else if(fromEsp8266.substr(8,2) == "SD") {  // Set Digital if true
                    // --- Build Reply String -----------------------------------------------
                    toEsp8266 = "Digital Channel ";
                    toEsp8266 += fromEsp8266.substr(10,2); //Digital Channel
                    toEsp8266 += " is ";
                    toEsp8266 += (fromEsp8266.substr(12,1)=="0") ? "LO" : "HI";
                    // ---- Send Reply String -----------------------------------------------
                    //toEspprintf(toEsp8266);        // Send Reply String to ESP8266 
                    //pc.printf("%s\n", toEsp8266);             // Send Reply String to Console
                    wifi.printf("%s\n", toEsp8266);             // Send Reply String to Console
//                    if(wifi.writeable()) {
//                        wifi.printf("%s\n", toEsp8266);  
//                    }
                    // --- Set Digital Channel State ----------------------------------------
                    chan = atoi(fromEsp8266.substr(10,2).c_str()); 
                    state = atoi(fromEsp8266.substr(12,1).c_str()); 
                    //digitalWrite(chan, state);             // Set Digital Output per request
                    //pc.printf("\nSTATE= ");
                    //pc.printf("%d", state);
                    LedD4 = state;
                }
                else if(fromEsp8266.substr(8,2) == "GD") {  // Get Digital if true
                    // --- Get Digital Channel State ----------------------------------------
                    chan = atoi(fromEsp8266.substr(10,2).c_str()); 
                    state = LedD4.read();             // Set Digital Output per request
                    // --- Build Reply String -----------------------------------------------
                    toEsp8266 = "Digital Channel ";
                    toEsp8266 += fromEsp8266.substr(10,2); //Digital Channel
                    toEsp8266 += " is ";
                    toEsp8266 += (state==0) ? "LO" : "HI";
                    // ---- Send Reply String -----------------------------------------------
                    //toEspprintf(toEsp8266);        // Send Reply String to ESP8266 
                    wifi.printf("%s\n",toEsp8266);             // Send Reply String to ESP
                }
                else if(fromEsp8266.substr(8,2) == "GA") {  // Get Analog if true
                    // --- Get Analog Channel Reading ---------------------------------------
                    chan = atoi(fromEsp8266.substr(10,2).c_str()); 
                    //Ain = 0.0048828 * (float) analogRead(chan);        // Read analog input
                    //ftoa(Ain,szAin, 2);
                    poti = getPoti('1');
                    // --- Build Reply String -----------------------------------------------
                    //toEsp8266 = "Analog Channel ";
                    toEsp8266 = "Poti 1 ";
                    // toEsp8266 += fromEsp8266.substr(10,2); //Analog Channel
                    toEsp8266 += " is ";
                    toEsp8266 += poti; //string(szAin);
                    // ---- Send Reply String -----------------------------------------------
                    //toEspprintf(toEsp8266);        // Send Reply String to ESP8266 
                    wifi.printf("%s\n",toEsp8266);             // Send Reply String to Console
                }
                else {
                    // ---- Send Reply String -----------------------------------------------
                    toEsp8266 = "Arduino does not recognize request.";
                    //toEspprintf(toEsp8266);        // Send Reply String to ESP8266 
                    //pc.printf("%s\n", toEsp8266);             // Send Reply String to Console
                    wifi.printf("%s\n", toEsp8266);             // Send Reply String to Console
                }
             }
            fromEsp8266 = "";
            //toEspSerial.flush();
//        }
//    }
}

/********************************************************
 *  URL Message Decoder
 ********************************************************/
 
int url_decode(char *encoded_str, char *decoded_str) {
   
    // While we're not at the end of the string (current character not NULL)
    while (*encoded_str) {
        // Check to see if the current character is a %
        if (*encoded_str == '%') {
    
            // Grab the next two characters and move encoded_str forwards
            encoded_str++;
            char high = *encoded_str;
            encoded_str++;
            char low = *encoded_str;
    
            // Convert ASCII 0-9A-F to a value 0-15
            if (high > 0x39) high -= 7;
            high &= 0x0f;
    
            // Same again for the low byte:
            if (low > 0x39) low -= 7;
            low &= 0x0f;
    
            // Combine the two into a single byte and store in decoded_str:
            *decoded_str = (high << 4) | low;
        } else {
            // All other characters copy verbatim
            *decoded_str = *encoded_str;
        }
    
        // Move both pointers to the next character:
        encoded_str++;
        decoded_str++;
    }
    // Terminate the new string with a NULL character to trim it off
    *decoded_str = 0;
    return 0;
}
void flushSerialBuffer() { 
    while (wifi.readable()) { 
        wifi.getc(); 
    } 
}

bool semi = false;
bool blank = false;  
  
void readData() {
    recChar = wifi.getc();
    if (recChar != '\n') {
        if(recChar != ':') semi = true;
        if(semi && (recChar != ' ')) blank = true;
        if(semi && blank)
            fromEsp8266 += recChar;                         // add it to receive string
    }
    else {
        recFlag = true;  
        semi = false; blank = false;
        flushSerialBuffer();
    }
}
int main() {
    pc.baud(115200);
    wifi.baud(115200);
    pc.printf("\f\n\r-------------ESP8266 Arduino -------------\n\r");
    wifi.attach(&readData);
    //wifi.printf("Hello WIFI\n");
    while(1) {
        if(recFlag) {
            pc.printf("readData: %s\n", fromEsp8266);  
            //fromEsp8266 = "Arduino_SD041";
            ReadAndProcessRequests();
            recFlag=false;
        }
        LedD1 = 1;
        wait(0.2);
        LedD1 = 0;
        wait(0.2);
    }
}