Sample code to HTTP using SIM900 and Arduino
Posted: Mon Feb 03, 2014 11:27 pm
Code: Select all
/*
* Description: This example shows how to do a GET action to a url.
* This example shows the AT commands (and the answers of the module) used
* to work with HTTP. For more information about the AT commands,
* refer to the AT command manual.
*
* Copyright (C) 2013 Libelium Comunicaciones Distribuidas S.L.
* http://www.libelium.com
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* Version 0.2
* Author: Alejandro Gallego
*/
int8_t answer;
int onModulePin= 2;
char data[512];
int data_size;
char aux_str[100];
char aux;
int x = 0;
void setup(){
pinMode(onModulePin, OUTPUT);
Serial.begin(115200);
Serial.println("Starting...");
power_on();
delay(3000);
// sets the PIN code
sendATcommand("AT+CPIN=****", "OK", 2000);
delay(3000);
while (sendATcommand2("AT+CREG?", "+CREG: 0,1", "+CREG: 0,5", 2000) == 0);
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) == 0)
{
delay(5000);
}
}
void loop(){
// Initializes HTTP service
answer = sendATcommand("AT+HTTPINIT", "OK", 10000);
if (answer == 1)
{
// Sets CID parameter
answer = sendATcommand("AT+HTTPPARA=\"CID\",1", "OK", 5000);
if (answer == 1)
{
// Sets url
answer = sendATcommand("AT+HTTPPARA=\"URL\",\"www.url.com\"", "OK", 5000);
if (answer == 1)
{
// Starts GET action
answer = sendATcommand("AT+HTTPACTION=0", "+HTTPACTION:0,200", 10000);
if (answer == 1)
{
x=0;
do{
sprintf(aux_str, "AT+HTTPREAD=%d,100", x);
if (sendATcommand2(aux_str, "+HTTPREAD:", "ERROR", 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++)
{
data[x] = Serial.read();
x++;
}
data[x] = '\0';
}
else
{
Serial.println("Download finished");
}
}
else if (answer == 2)
{
Serial.println("Error from HTTP");
}
else
{
Serial.println("Error getting the url");
data_size = 0;
}
sendATcommand("", "+HTTPACTION:0,200", 20000);
}while (data_size > 0);
Serial.print("Data received: ");
Serial.println(data);
}
else
{
Serial.println("Error getting the url");
}
}
else
{
Serial.println("Error setting the url");
}
}
else
{
Serial.println("Error setting the CID");
}
}
else
{
Serial.println("Error initializating");
}
sendATcommand("AT+HTTPTERM", "OK", 5000);
delay(5000);
}
void power_on(){
uint8_t answer=0;
// checks if the module is started
answer = sendATcommand("AT", "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 = sendATcommand("AT", "OK", 2000);
}
}
}
int8_t sendATcommand(char* ATcommand, char* expected_answer1, unsigned int timeout){
uint8_t x=0, answer=0;
char response[100];
unsigned long previous;
memset(response, '\0', 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){
response[x] = Serial.read();
x++;
// check if the desired answer is in the response of the module
if (strstr(response, expected_answer1) != 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, '\0', 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){
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;
}