convert a decimal value to its binary representation ( string )

Wanted to share this snippet of code which I used to display a decimal numbers binary representation. It is quite self explanatory and easy to understand.

/**
  * Turns a decimal value to its binary representation
  */
char* dec2binWzerofill(unsigned long Dec, unsigned int bitLength){
    return dec2binWcharfill(Dec, bitLength, '0');
}

char* dec2binWcharfill(unsigned long Dec, unsigned int bitLength, char fill){
  static char bin[64];
  unsigned int i=0;
unsigned int j;
  while (Dec > 0) {
    bin[32+i++] = ((Dec & 1) > 0) ? '1' : fill;
    Dec = Dec >> 1;
  }

  for ( j = 0; j< bitLength; j++) {
    if (j >= bitLength - i) {
      bin[j] = bin[ 31 + i - (j - (bitLength - i)) ];
    }else {
      bin[j] = fill;
    }
  }
  bin[bitLength] = '';

  return bin;
}
 

Analog pH Meter with PIC16F684 and arduino

Need to measure water quality and other parameters?  DF Robot’s Analog pH Meter Kit is  specially designed for simple interface and has convenient and practical connector and a bunch of features. Get pH measurements at ± 0.1pH (25 ℃). For most hobbyist this great accuracy range and it’s low cost makes this a great tool for biorobotics and other projects! It has an LED which works as the Power Indicator, a BNC connector and PH2.0 sensor interface. To use it, just connect the pH sensor with BND connector, and plug the PH2.0 interface into the analog input port of any micro-controller.

The Wiki page  has a sample code for using this kit with arduino,  along with schematic, specifications, features ,precautions and setup Instructions. The arduino Interfacing is simple and the schematic and code is available on the wiki page.

PH_meter_connection1_(1)

Interfacing with a pic is also straight forward, Shawon Shahryiar shared his project where he used a PIC16F684. Below is the demonstration video and code.

/*
Coder: Shawon Shahryiar
https://www.facebook.com/groups/ArduinoBangla/
https://www.facebook.com/groups/microarena/
https://www.facebook.com/MicroArena
 */


#include <16F684.h>

#device *= 16
#device ADC = 10

#fuses NOWDT, INTRC_IO, PROTECT, PUT, CPD
#fuses NOBROWNOUT, NOMCLR, NOIESO, FCMEN

#use delay (internal = 4MHz)


#include "lcd.c"


#define const_A 0.00171016
#define LED	pin_C3


const unsigned char symbol[16] ={
    0x00, 0x1F, 0x1F, 0x1F, 0x1F, 0x1F, 0x00, 0x00,
    0x00, 0x00, 0x0E, 0x0E, 0x0E, 0x00, 0x00, 0x00
};


void setup();
void lcd_symbol();
unsigned long adc_avg();
void show_bar(unsigned char value);

void main() {
    unsigned char samples_A = 0x00;
    unsigned char samples_B = 0x00;
    unsigned long temp = 0x0000;
    unsigned long avg = 0x0000;
    unsigned long buffer[10];
    float pH_value = 0.0;

    memset(buffer, 0x00, sizeof (buffer));

    setup();

    while (TRUE) {
        for (samples_A = 0; samples_A < 10; samples_A++) {
            buffer[samples_A] = adc_avg();
            delay_ms(9);
        }

        for (samples_A = 0; samples_A < 9; samples_A++) {
            for (samples_B = (1 + samples_A); samples_B < 10; samples_B++) {
                if (buffer[samples_A] > buffer[samples_B]) {
                    temp = buffer[samples_A];
                    buffer[samples_A] = buffer[samples_B];
                    buffer[samples_B] = temp;
                }
            }
        }

        avg = 0;

        for (samples_A = 3; samples_A < = 6; samples_A++) {
            avg += buffer[samples_A];
        }

        avg >>= 2;

        pH_value = (avg * const_A);

        lcd_gotoxy(1, 1);
        printf(lcd_putc, "pH Value: %2.2g ", pH_value);
        show_bar(((unsigned char) pH_value));
    };
}

void setup() {
    disable_interrupts(GLOBAL);
    setup_WDT(WDT_off);
    setup_oscillator(OSC_4MHz);
    setup_comparator(NC_NC_NC_NC);
    setup_ADC(ADC_clock_div_8);
    setup_ADC_ports(sAN0);
    set_ADC_channel(0);
    setup_CCP1(CCP_off);
    setup_timer_0(T0_internal);
    setup_timer_1(T1_disabled);
    setup_timer_2(T2_disabled, 255, 1);
    set_timer0(0x00);
    set_timer1(0x0000);
    set_timer2(0x00);
    lcd_init();
    lcd_symbol();
    delay_ms(4000);
}

void lcd_symbol() {
    unsigned char s = 0;

    lcd_send_byte(0, 0x40);

    for (s = 0x00; s < = 0x0F; s++) {
        lcd_send_byte(1, symbol[s]);
    }

    lcd_send_byte(0, 0x80);
}

unsigned long adc_avg() {
    unsigned char samples = 4;
    unsigned long avg = 0;

    while (samples > 0) {
        read_adc(adc_start_only);
        while (!adc_done());
        avg += read_adc(adc_read_only);
        samples--;
    }
    avg /= 4.0;

    return avg;
}

void show_bar(unsigned char value) {
    unsigned char x_pos = 0;

    for (x_pos = 1; x_pos < = 16; x_pos++) {
        lcd_gotoxy(x_pos, 2);
        lcd_putc(0);
    }

    lcd_gotoxy((value + 1), 2);
    lcd_putc(1);

    output_toggle(LED);
    delay_ms(100);
} 
 

Pic based temperature sensor with 7 segment display and ds18b20

This circuit is a Digital Temerature Sensor using a Dallas ‘1-wire’ DS18B20 Digital Thermometer


Firstly I would like to thank Pommie and Mike, K8LH from the Electro Tech Online Forum for their genourous help. This has been the most challenging project to date and they have helped immensely. They have tought me many valuable lessons about programming in Assembly language and it has really assitsted me in getting this project up and running.

Note: I would like to make a point that some snippets of their own code is used in this program. I have used it with their permission and please observe any copyrights or name recognition placed in the code. If you wish to use their snippets of code, please contact them via the Electro-Tech-Online forum.

How It Works

The DS18B20 is a direct-to-digital temperature sensor using Maxim’s exclusive 1-Wire bus protocol that implements bus communication using one control signal. In regards to hardware, this particular sensor is particularly easy to interface to. It only requires 1 external pull-up resistor to operate as opposed to an analogue sensor which possibly needs multiple external components such as resistors and op-amps.

In regards to software, opposed to analogue sensors, the Dallas 1-wire digital sensors are arguably as easy to interface to. While an analogue sensor will need an Analogue to Digital conversion using a voltage reference and possibly using an op-amp, the Dallas 1-wire direct to digital sensors require precise timing when it comes to communication. This program is fairly basic in principle as all it does is obtain temperature data from the DS18B20 sensor and display the temperature in Degrees Celsius on a 4 digit, 7 segment display. But when it comes to actually doing this, as you will see from the .ASM file, it is more complicated than it sounds. In words; the program first initialises the PIC16F628A Microcontroller. It assigns the Inputs and Outputs, zero’s all bank 0 RAM, initialises the display column select bit and configures TIMER 2. TIMER 2 is used to interrupt the normal loop of the program to update the 7 segment LED display.

After the Microcontroller has been setup, it begins communication with the DS18B20 Temperature Sensor. Communication routines take up just under half of the program memory. After the temperature has been gathered and stored in RAM, the Microcontroller takes the 12-bit signed/fraction integer and converts it into a decimal number then stores it in four general purpose registers in RAM.

For example, take the number D’95.8′. It is stored like this:

HUNS register = 0
TENS register = 9
ONES register = 5
TENTHS register = 8

These registers are then used within the Interrupt Service Routine to call a table to obtain display data.
The program runs continuously, updating the temperature on the display just over once per 1 second.

Features Summary:

  • Temperature data gathered more than once per second.
  • TIMER 2 interrupt driven display.
  • Program expandable to include multiple sensors on the same 1-Wire bus.
  • Temperature range of -55.0 – 127.9 Degrees Celsius.

Please see the DS18B20 Datasheet for detailed information on the device.

schematicbreadboard

 

 

digitaltemperaturesensorbasic.zip

Here is the complete project   (with explanation , code, schematic and video)

 

Testing apple push notifications on iOS simulator

You can not send / receive apple push notifications on iOS simulator as Push notifications are not available in the simulator. They require a provisioning profile from iTunes Connect, and thus are required to be installed on a device.

In order to test your app’s response to a push notification you either have to use a real device or you may use a library called SimulatorRemoteNotifications.

SimulatorRemoteNotifications is a library to send mock remote notifications to the iOS simulator.

It’s pretty easy to send push via terminal:

echo -n '{"message":"message"}' | nc -4u -w1 localhost 9930
echo -n '{"aps":{"alert" : "message","badge" : 99,"sound" : "default"}, "myField" : 54758}'

The library extends UIApplication by embedding a mini server that listen for UDP packets containing JSON-formated payload, and a service to send notifications to the mini server. It also includes the iOS Simulator Notifications MacOSX app to help you send the mock notifications.

Note that SimulatorRemoteNotifications does not send notification through Apple’s Push Service.

More details at https://github.com/acoomans/SimulatorRemoteNotifications

 

 

Proteus and MikroC Tutorial [Video]

screenshot

Proteus as we already discussed earlier in post regarding COMPIM ,is a great tool for embedded Engineers, so here is a  very simple and easy to get started with Proteus and MikroC tutorial through flash demonstrations.These tutorials are hosted on http://smainj.free.fr (These are no more available) but i would embed them one by one in my posts so that they are accessed easily and can be viewed online. you can download them from the link given  and you can view them online here by clicking the link below.

Tutorail1: In this tutorial you would learn

  • Design A schematic  in Proteus using ISIS
  • Using mikroC to write a program
  • Simulate program and circuit
  • Convert Schematic from ISIS to PCB in ARES
Proteus Tutorial, simulating code in VSM & PCB… by dostmhd
CLICK HERE to view This as a flash video in a player with pause/play and seek bar….

 

 

 

strip non-ASCII characters from a string using RegEx (Regular expressions)

In case you have a string data which has some non ASCII characters and want to strip off all those non-ASCII characters the following regular expression will help you.

[^u0000-u007F]+

Explanation

  • [^u0000-u007F]+ match a single character not present in the list below
    Quantifier: + Between one and unlimited times, as many times as possible
  • u0000-u007F a single character in the range between the following two characters
    • u0000 the literal character u0000 (case sensitive)
    • u007F the literal character u007F (case sensitive)

^ is the not operator. It tells the regex to find everything that doesn’t match, instead of everything that does match.

The u####-u#### says which characters match.u0000-u007F is the equivilent of the first 255 characters in utf-8 or unicode, which are always the ASCII characters. So you match every non ASCII character (because of the not)

… 

 

upload/downlaod file from FTP using AT commands (Sim900 + arduino)

In the previous post I explained how to make a connection and send data via TCP connection on SIM900 and similar modems. This post is going to be about FTP connection. FTP stands for “file transfer protocol.” FTP powers one of the fundamental Internet functions and is the prescribed method for the transfer of files between computers. It is also the easiest and most secure way to exchange files over the Internet.

Without going into much details I would show the related AT commands and brief description. Later I would include sample code for FTP upload/download using arduino and SIM900

AT command Response Description
AT+SAPBR OK Configures GPRS profile.
AT+FTPCID=1 OK Selects profile 1 for FTP.
AT+FTPSERV=”****” OK Sets FTP server domain name or IP address. **** is the domain name or the IP.
AT+FTPPORT=*** OK Sets FTP server port. *** is the port.
AT+FTPUN=”***” OK Sets user name for FTP server access. *** is the user name.
AT+FTPPW=”***” OK Sets password for FTP server access. *** is the password.
AT+FTPPUTNAME=”****” OK Sets destiny name for the file.*** is the name of the file.
AT+FTPPUTPATH=”****” OK Sets destiny file path. *** is the path of the file.
AT+FTPPUT OK Use to put a file into the FTP server.
AT+FTPGETNAME=”****” OK Sets origin name for the file.*** is the name of the file.
AT+FTPGETPATH=”****” OK Sets origin file path. *** is the path of the file.
AT+FTPGET Use to get a file into the FTP server.

Make sure you have a server and note the ftp port, we would consider using the default port 21. Switch on your modem and make sure pin code is disabled or properly entered and that GPRS connection is available.

  1. Configure GPRS by sending AT+SAPBR=3,1,”Contype”,”GPRS”r  .
  2. Set APN by sending   AT+SAPBR=3,1,”APN”,”your apn”r  .replace your apn with APN for your network.
  3. Now set the username and password for the apn (replace username and password with correct values )
    AT+SAPBR=3,1,”USER”,”username”r  .
    AT+SAPBR=3,1,”PASS”,”password”r
  4. Connect to GPRS connection by sending AT+SAPBR=1,1r, when connected Modem will respond with OK
  5. Now select profile 1 for FTP by sending AT+FTPCID=1r
  6. Now set FTP server domain or ip using the command AT+FTPSERV=ftp.yourserver.comr
  7. Set FTP port by AT+FTPPORT=21r
  8. Now send FTP credentials using AT+FTPUN=user_namer and AT+FTPPW=”password”r
  9. To get a file from FTP send AT+FTPGETNAME=file_namer
  10.  Now set the path of the file AT+FTPGETPATH=/path/r
  11. Now send AT+FTPGET=1r and wait for response from server, which starts with +FTPGET:1,1
  12. To upload a file to FTP server send AT+FTPPUTNAME=file_namer
  13. Now set path AT+FTPPUTPATH=/pathr
  14. Now send AT+FTPPUT=1 and wait for +FTPPUT:1,1 after which you need to send the content of file to be uploaded.

int8_t answer;
int onModulePin = 2;
char aux_str[30];

char incoming_data[120];

char test_str[ ]= "0000000011111111222222223333333344444444555555556666666677777777000000001111111122222222333333334444";

int data_size, aux;


void setup(){

    pinMode(onModulePin, OUTPUT);
    Serial.begin(115200);


    Serial.println("Starting...");
    power_on();

    delay(5000);

    Serial.println("Connecting to the network...");

    while( (sendATcommand("AT+CREG?", "+CREG: 0,1", 500)
            || sendATcommand("AT+CREG?", "+CREG: 0,5", 500)) == 0 );

    configure_FTP();

    uploadFTP();

    downloadFTP();

    Serial.print("Incoming data: ");
    Serial.println(incoming_data);
}


void loop(){

}


void configure_FTP(){

    sendATcommand("AT+SAPBR=3,1,"Contype","GPRS"", "OK", 2000);
    sendATcommand("AT+SAPBR=3,1,"APN","APN"", "OK", 2000);
    sendATcommand("AT+SAPBR=3,1,"USER","user_name"", "OK", 2000);
    sendATcommand("AT+SAPBR=3,1,"PWD","password"", "OK", 2000);

    while (sendATcommand("AT+SAPBR=1,1", "OK", 20000) != 1);
    sendATcommand("AT+FTPCID=1", "OK", 2000);
    sendATcommand("AT+FTPSERV="ftp.yourserver.com"", "OK", 2000);
    sendATcommand("AT+FTPPORT=21", "OK", 2000);
    sendATcommand("AT+FTPUN="user_name"", "OK", 2000);
    sendATcommand("AT+FTPPW="password"", "OK", 2000);

}


void uploadFTP(){

    sendATcommand("AT+FTPPUTNAME="file_name"", "OK", 2000);
    sendATcommand("AT+FTPPUTPATH="/path"", "OK", 2000);
    if (sendATcommand("AT+FTPPUT=1", "+FTPPUT:1,1,", 30000) == 1)
    {
        data_size = 0;
        while(Serial.available()==0);
        aux = Serial.read();
        do{
            data_size *= 10;
            data_size += (aux-0x30);
            while(Serial.available()==0);
            aux = Serial.read();
        }
        while(aux != 0x0D);

        if (data_size >= 100)
        {
            if (sendATcommand("AT+FTPPUT=2,100", "+FTPPUT:2,100", 30000) == 1)
            {
                Serial.println(sendATcommand(test_str, "+FTPPUT:1,1", 30000), DEC);
                Serial.println(sendATcommand("AT+FTPPUT=2,0", "+FTPPUT:1,0", 30000), DEC);
                Serial.println("Upload done!!");
            }
            else
            {
                sendATcommand("AT+FTPPUT=2,0", "OK", 30000);
            }
        }
        else
        {
            sendATcommand("AT+FTPPUT=2,0", "OK", 30000);
        }
    }
    else
    {
        Serial.println("Error openning the FTP session");
    }
}

void downloadFTP(){

    int x = 0;

    sendATcommand("AT+FTPGETNAME="file_name"", "OK", 2000);
    sendATcommand("AT+FTPGETPATH="/path"", "OK", 2000);
    if (sendATcommand("AT+FTPGET=1 ", "+FTPGET:1,1", 30000) == 1)
    {
        do{
            if (sendATcommand2("AT+FTPGET=2,50", "+FTPGET:2,", "+FTPGET:1,", 30000) == 1)
            {
                data_size = 0;
                while(Serial.available()==0);
                aux = Serial.read();
                do{
                    data_size *= 10;
                    data_size += (aux-0x30);
                    while(Serial.available()==0);
                    aux = Serial.read();
                }while(aux != 0x0D);

                Serial.print("Data received: ");
                Serial.println(data_size);

                if (data_size > 0)
                {
                    while(Serial.available() < data_size);
                    Serial.read();

                    for (int y = 0; y < data_size; y++)
                    {
                        incoming_data[x] = Serial.read();
                        x++;
                    }
                    incoming_data[x] = '';
                }
                else
                {
                    Serial.println("Download finished");
                }
            }
            else if (answer == 2)
            {
                Serial.println("Error from FTP");
            }
            else
            {
                Serial.println("Error getting the file");
                data_size = 0;
            }
        }while (data_size > 0);
    }
    else
    {
        Serial.println("Error openning the FTP session");
    }
}




void power_on(){

    uint8_t answer=0;

    // checks if the module is started
    answer = sendATcommand("AT", "OK", 2000);
    if (answer == 0)
    {
        digitalWrite(onModulePin,HIGH);
        delay(3000);
        digitalWrite(onModulePin,LOW);

        while(answer == 0){     // Send AT every two seconds and wait for the answer
            answer = sendATcommand("AT", "OK", 2000);
        }
    }
}


int8_t sendATcommand(char* ATcommand, char* expected_answer, unsigned int timeout){

    uint8_t x=0,  answer=0;
    char response[100];
    unsigned long previous;

    memset(response, '', 100);    // Initialize the string

    delay(100);

    while( Serial.available() > 0) Serial.read();    // Clean the input buffer

    Serial.println(ATcommand);    // Send the AT command


        x = 0;
    previous = millis();

    // this loop waits for the answer
    do{
        if(Serial.available() != 0){
            // if there are data in the UART input buffer, reads it and checks for the asnwer
            response[x] = Serial.read();
            //Serial.print(response[x]);
            x++;
            // check if the desired answer  is in the response of the module
            if (strstr(response, expected_answer) != NULL)
            {
                answer = 1;
            }
        }
    }
    // Waits for the asnwer with time out
    while((answer == 0) && ((millis() - previous) < timeout));

        return answer;
}

int8_t sendATcommand2(char* ATcommand, char* expected_answer1,
            char* expected_answer2, unsigned int timeout){

    uint8_t x=0,  answer=0;
    char response[100];
    unsigned long previous;

    memset(response, '', 100);    // Initialize the string

    delay(100);

    while( Serial.available() > 0) Serial.read();    // Clean the input buffer

    Serial.println(ATcommand);    // Send the AT command


        x = 0;
    previous = millis();

    // this loop waits for the answer
    do{
        // if there are data in the UART input buffer, reads it and checks for the asnwer
        if(Serial.available() != 0){
            response[x] = Serial.read();
            x++;
            // check if the desired answer 1 is in the response of the module
            if (strstr(response, expected_answer1) != NULL)
            {
                answer = 1;
            }
            // check if the desired answer 2 is in the response of the module
            if (strstr(response, expected_answer2) != NULL)
            {
                answer = 2;
            }
        }
        // Waits for the asnwer with time out
    }while((answer == 0) && ((millis() - previous) < timeout));

        return answer;
}


 

 

TCP connection over GPRS using SIM900 and similar modems using AT commands

GSM/GPRS modems are getting very common these days, as prices are getting cheaper and cheaper. Apart from providing SMS and call functions to my projects I also wanted to communicate via TCP.

Although there are many documents and blog posts to help but I have always found that they either are answers to specific problem faced by someone or not providing complete details.  In this post I would first explain the AT commands used in brief. You may connect your SIM900 to your computer via a serial/usb and test these commands. In the later part of this post I would include arduino example code.

AT commands for TCP/UDP Connection with example response and a brief description are given in the table below. Refer to the AT commands manual of your modem for details

AT command Response Description
AT  OK test command. reply is OK
AT+CGATT?  +CGATT:n checks if GPRS is attached? n=1 if attached
AT+CIPMUX=n  OK use n as 0 for single connection
or use 1 for multiple connections
AT+CSTT=”apn”,”username”,”pass” OK Sets APN, user name and password
AT+CIICR  OK Brings up wireless connection
AT+CIFSR  ip address Get local IP address if connected
AT+CIPSTART=“TYPE” , “domain”, “port”  Connected Establishes a connection with a server. Type can be UDP or TCP
AT+CIPSEND  > Sends data when the a connection is established.
AT+CIPCLOSE  OK Closes the connection
AT+CIPSHUT  SHUT OK resets IP session if any

how to make a connection:

  1. Send ATr and wait for a response from the modem. You should recieve OK
    if everything is set.
  2. Make sure that the Modem has registered to network and that PIN code is disabled on the SIM. Send AT+CGATT?r to check if GPRS is attached or not.  +CGATT: 1 indicates that GPRS is attached.
  3. Send AT+CIPSHUTr . Although its optional this will be helpful as it resets IP session if any. you will get a response SHUT OK .
  4. Send AT+CIPMUX=0 to set a single connection mode, response would be OK
  5. Now set APN settings by AT+CSTT= “apn ”, “username”, “password”r . replace apn, username and password to match APN (Access Point Name) ,username and password for your service provider.
  6. Now send AT+CIICRr , this will bring up the wireless connection. OK is received on successful connection
  7. Send AT+CIFSRr , this will reply with the IP address the modem has been assigned.
  8. Send AT+CIPSTART=”TCP”,”server domain name or ip”,”port”r, replace the domain name/ip and port with appropriate values, on connection modem will reply with CONNECT OK
  9. Now you can send your data using AT+CIPSENDr  AT command. modem will respond with > indicating it is ready to receive data to be sent. Type in your data.
  10. Now the modem is waiting for the ASCII 26  that is control+z on keyboard. Depending on the terminal software used you can either press control and Z together on keyboard or send hex value 0x1A. The modem will then send the response from server.
  11. Now send AT+CIPSHUT to shut down the connection. Modem will reply with SHUT OK 
  12. cheers 🙂

ARDUINO CODE :

Below is example code for single and multiple connection using arduino and sim900

int8_t answer;
int onModulePin= 2;
char aux_str[50];
char ip_data[40]="Test string from GPRS shieldrn";
void setup(){
    pinMode(onModulePin, OUTPUT);
    Serial.begin(115200);
    Serial.println("Starting...");
    power_on();
    delay(3000);
    // sets the PIN code
    sendATcommand2("AT+CPIN=****", "OK", "ERROR", 2000);
    delay(3000);
    Serial.println("Connecting to the network...");
    while( sendATcommand2("AT+CREG?", "+CREG: 0,1", "+CREG: 0,5", 1000)== 0 );
}
void loop(){
    // Selects Single-connection mode
    if (sendATcommand2("AT+CIPMUX=0", "OK", "ERROR", 1000) == 1)
    {
        // Waits for status IP INITIAL
        while(sendATcommand2("AT+CIPSTATUS", "INITIAL", "", 500)  == 0 );
        delay(5000);

        // Sets the APN, user name and password
        if (sendATcommand2("AT+CSTT="APN","user_name","password"", "OK",  "ERROR", 30000) == 1)
        {
            // Waits for status IP START
            while(sendATcommand2("AT+CIPSTATUS", "START", "", 500)  == 0 );
            delay(5000);

            // Brings Up Wireless Connection
            if (sendATcommand2("AT+CIICR", "OK", "ERROR", 30000) == 1)
            {
                // Waits for status IP GPRSACT
                while(sendATcommand2("AT+CIPSTATUS", "GPRSACT", "", 500)  == 0 );
                delay(5000);

                // Gets Local IP Address
                if (sendATcommand2("AT+CIFSR", ".", "ERROR", 10000) == 1)
                {
                    // Waits for status IP STATUS
                    while(sendATcommand2("AT+CIPSTATUS", "IP STATUS", "", 500)  == 0 );
                    delay(5000);
                    Serial.println("Openning TCP");

                    // Opens a TCP socket
                    if (sendATcommand2("AT+CIPSTART="TCP","IP_address","port"",
                            "CONNECT OK", "CONNECT FAIL", 30000) == 1)
                    {
                        Serial.println("Connected");

                        // Sends some data to the TCP socket
                        sprintf(aux_str,"AT+CIPSEND=%d", strlen(ip_data));
                        if (sendATcommand2(aux_str, ">", "ERROR", 10000) == 1)
                        {
                            sendATcommand2(ip_data, "SEND OK", "ERROR", 10000);
                        }

                        // Closes the socket
                        sendATcommand2("AT+CIPCLOSE", "CLOSE OK", "ERROR", 10000);
                    }
                    else
                    {
                        Serial.println("Error openning the connection");
                    }
                }
                else
                {
                    Serial.println("Error getting the IP address");
                }
            }
            else
            {
                Serial.println("Error bring up wireless connection");
            }
        }
        else
        {
            Serial.println("Error setting the APN");
        }
    }
    else
    {
        Serial.println("Error setting the single connection");
    }

    sendATcommand2("AT+CIPSHUT", "OK", "ERROR", 10000);
    delay(10000);
}

void power_on(){

    uint8_t answer=0;

    // checks if the module is started
    answer = sendATcommand2("AT", "OK", "OK", 2000);
    if (answer == 0)
    {
        // power on pulse
        digitalWrite(onModulePin,HIGH);
        delay(3000);
        digitalWrite(onModulePin,LOW);

        // waits for an answer from the module
        while(answer == 0){     // Send AT every two seconds and wait for the answer
            answer = sendATcommand2("AT", "OK", "OK", 2000);
        }
    }

}

int8_t sendATcommand2(char* ATcommand, char* expected_answer1,
        char* expected_answer2, unsigned int timeout){

    uint8_t x=0,  answer=0;
    char response[100];
    unsigned long previous;

    memset(response, '', 100);    // Initialize the string

    delay(100);

    while( Serial.available() > 0) Serial.read();    // Clean the input buffer

    Serial.println(ATcommand);    // Send the AT command

    x = 0;
    previous = millis();

    // this loop waits for the answer
    do{
        // if there are data in the UART input buffer, reads it and checks for the asnwer
        if(Serial.available() != 0){
            response[x] = Serial.read();
            x++;
            // check if the desired answer 1  is in the response of the module
            if (strstr(response, expected_answer1) != NULL)
            {
                answer = 1;
            }
            // check if the desired answer 2 is in the response of the module
            else if (strstr(response, expected_answer2) != NULL)
            {
                answer = 2;
            }
        }
    }
    // Waits for the asnwer with time out
    while((answer == 0) && ((millis() - previous) < timeout));

    return answer;
}
int8_t answer;
int onModulePin= 2;
char aux_str[50];

char ip_data[40]="Test string from GPRS shieldrn";

void setup(){

    pinMode(onModulePin, OUTPUT);
    Serial.begin(115200);

    Serial.println("Starting...");
    power_on();

    delay(3000);

    // sets the PIN code
    sendATcommand2("AT+CPIN=****", "OK", "ERROR", 2000);

    delay(3000);

    Serial.println("Connecting to the network...");

    while( sendATcommand2("AT+CREG?", "+CREG: 0,1", "+CREG: 0,5", 1000) == 0 );

}


void loop(){


    // Selects Multi-connection mode
    if (sendATcommand2("AT+CIPMUX=1", "OK", "ERROR", 1000) == 1)
    {
        // Waits for status IP INITIAL
        while(sendATcommand2("AT+CIPSTATUS", "INITIAL", "", 500)  == 0 );
        delay(5000);

        // Sets the APN, user name and password
        if (sendATcommand2("AT+CSTT="APN","user_name","password"", "OK",  "ERROR", 30000) == 1)
        {
            // Waits for status IP START
            while(sendATcommand2("AT+CIPSTATUS", "START", "", 500)  == 0 );
            delay(5000);

            // Brings Up Wireless Connection
            if (sendATcommand2("AT+CIICR", "OK", "ERROR", 30000) == 1)
            {
                // Waits for status IP GPRSACT
                while(sendATcommand2("AT+CIPSTATUS", "GPRSACT", "", 500)  == 0 );
                delay(5000);

                // Gets Local IP Address
                if (sendATcommand2("AT+CIFSR", ".", "ERROR", 10000) == 1)
                {
                    // Waits for status IP STATUS
                    while(sendATcommand2("AT+CIPSTATUS", "IP STATUS", "", 500)  == 0 );
                    delay(5000);
                    Serial.println("Openning TCP");

                    // Opens a TCP socket with connection 1
                    if (sendATcommand2("AT+CIPSTART=1,"TCP","IP_address","port"",
                                    "CONNECT OK", "CONNECT FAIL", 30000) == 1)
                    {
                        Serial.println("Connected");

                        // Sends some data to the TCP socket
                        sprintf(aux_str,"AT+CIPSEND=1,%d", strlen(ip_data));
                        if (sendATcommand2(aux_str, ">", "ERROR", 10000) == 1)
                        {
                            delay(500);
                            sendATcommand2(ip_data, "SEND OK", "ERROR", 10000);
                        }

                        // Closes the socket
                        sendATcommand2("AT+CIPCLOSE=1", "CLOSE OK", "ERROR", 10000);
                    }
                    else
                    {
                        Serial.println("Error openning the connection 1");
                    }

                }
                else
                {
                    Serial.println("Error getting the IP address");
                }
            }
            else
            {
                Serial.println("Error bring up wireless connection");
            }
        }
        else
        {
            Serial.println("Error setting the APN");
        }
    }
    else
    {
        Serial.println("Error setting the multi-connection");
    }

    sendATcommand2("AT+CIPSHUT", "OK", "ERROR", 10000);
    delay(10000);
}

void power_on(){

    uint8_t answer=0;

    // checks if the module is started
    answer = sendATcommand2("AT", "OK", "OK", 2000);
    if (answer == 0)
    {
        // power on pulse
        digitalWrite(onModulePin,HIGH);
        delay(3000);
        digitalWrite(onModulePin,LOW);

        // waits for an answer from the module
        while(answer == 0){     // Send AT every two seconds and wait for the answer
            answer = sendATcommand2("AT", "OK", "OK", 2000);
        }
    }

}

int8_t sendATcommand2(char* ATcommand, char* expected_answer1,
        char* expected_answer2, unsigned int timeout){

    uint8_t x=0,  answer=0;
    char response[100];
    unsigned long previous;

    memset(response, '', 100);    // Initialize the string

    delay(100);

    while( Serial.available() > 0) Serial.read();    // Clean the input buffer

    Serial.println(ATcommand);    // Send the AT command

    x = 0;
    previous = millis();

    // this loop waits for the answer
    do{
        // if there are data in the UART input buffer, reads it and checks for the asnwer
        if(Serial.available() != 0){
            response[x] = Serial.read();
            x++;
            // check if the desired answer 1  is in the response of the module
            if (strstr(response, expected_answer1) != NULL)
            {
                answer = 1;
            }
            // check if the desired answer 2 is in the response of the module
            else if (strstr(response, expected_answer2) != NULL)
            {
                answer = 2;
            }
        }
    }
    // Waits for the asnwer with time out
    while((answer == 0) && ((millis() - previous) < timeout));

    return answer;
}