HTTP Post with sim900a not working

Projects Programming
1

Trying to post data using sim900a with uno. here is my code below. The response is also attached below. some how the error is coming on post request.

#include <SoftwareSerial.h>
/* Create object named SIM900 of the class SoftwareSerial */
SoftwareSerial SIM900(8, 7);
void setup() {
  SIM900.begin(9600);  /* Define baud rate for software serial communication */
  Serial.begin(9600); /* Define baud rate for serial communication */
}

void loop() {
   if (SIM900.available())
    Serial.write(SIM900.read());
 
  SIM900.println("AT");
  delay(1000);
 
  SIM900.println("AT+CPIN?");
  delay(1000);
 
  SIM900.println("AT+CREG?");
  delay(1000);
 
  SIM900.println("AT+CGATT?");
  delay(1000);
 
  SIM900.println("AT+CIPSHUT");
  delay(1000);
 
  SIM900.println("AT+CIPSTATUS");
  delay(2000);
 
  SIM900.println("AT+CIPMUX=0");
  delay(2000);
 
  ShowSerialData();
 
  SIM900.println("AT+CSTT=\"ZONGWAP\"");//start task and setting the APN,
  delay(1000);
 
  ShowSerialData();
 
  SIM900.println("AT+CIICR");//bring up wireless connection
  delay(3000);
 
  ShowSerialData();
 
  SIM900.println("AT+CIFSR");//get local IP adress
  delay(2000);
 
  ShowSerialData();
 
  SIM900.println("AT+CIPSPRT=0");
  delay(3000);
 
  ShowSerialData();
  
  
   SIM900.println("GET https://api.thingspeak.com/update?api_key=546B5AHDKNTOA1DF&field1=98&field2=18");  
   
delay(5000);
  ShowSerialData();
  delay(4000);
  SIM900.println((char)26);
  SIM900.println();
  ShowSerialData();
 
  SIM900.println("AT+CIPSHUT");//close the connection
  delay(100);
  ShowSerialData();
}

void ShowSerialData()
{
  while(SIM900.available()!=0)  /* If data is available on serial port */
  Serial.write(char (SIM900.read())); /* Print character received on to the serial monitor */
}

Here is the response.

15:59:32.225 -> AT
15:59:32.225 -> 
15:59:32.225 -> OK
15:59:32.225 -> AT+CPIN?
15:59:32.225 -> 
15:59:32.225 -> +CPIN: READY
15:59:32.272 -> 
15:59:32.272 -> OK
15:59:32.272 -> AT+CREG?
15:59:32.272 -> 
15:59:32.272 -> +CREG: 0,1
15:59:32.326 -> 
15:59:32.326 -> OK
15:59:32.326 -> AT+CGATT?
15:59:32.326 -> 
15:59:32.326 -> +CGATT: 1
15:59:32.326 -> 
15:59:32.326 -> OK
15:59:32.326 -> AT+CIPSHUT
15:59:32.326 -> 
15:59:32.326 -> SHUT OK
15:59:32.326 -> AT+CIPSTATUS
15:59:32.373 -> 
15:59:32.373 -> OK
15:59:32.373 -> 
15:59:32.373 -> STATE: IP INITIAL
15:59:32.426 -> AT+CIPMUX=0
15:59:32.426 -> 
15:59:32.426 -> OK
15:59:33.427 -> AT+CSTT="ZONGWAP"
15:59:33.427 -> 
15:59:33.427 -> OK
15:59:36.396 -> AT+CIICR
15:59:36.396 -> 
15:59:36.396 -> OK
15:59:38.438 -> AT+CIFSR
15:59:38.438 -> 
15:59:38.438 -> 10.123.211.202
15:59:41.421 -> AT+CIPSPRT=0
15:59:41.421 -> 
15:59:41.421 -> OK
15:59:46.496 -> GET https://api.thingspeak.com/update?api_key=546B5AHDKNTOA1DF&field1=98&field2=18
15:59:46.599 -> 
15:59:46.599 -> ERROR
2

I cannot find an AT command to do the POST. Just sending a GET... to the SIM returns an error of course.

3

Please verify if the link is correct.

5

Yes the link is correct.

6

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