HTTPREAD missing characters with Arduino and SIM900

Question

I am using a SIM900 module with my Arduino and it is missing characters although it is returning the right number of characters expected. I have ERROR on AT+SAPBR=1,1 and AT+HTTPINIT so I am not sure if this is the reason for it. Im not sure how to fix these issues either.

AT+CGATT?

+CGATT: 1

OK
AT+CGATT=1

OK
AT+SAPBR=3,1,"CONTYPE","GPRS"

OK
AT+SAPBR=3,1,"APN","mobile.o2.co.uk"

OK
AT+SAPBR=1,1

ERROR
AT+HTTPINIT

ERROR
AT+HTTPPARA="URL","http://www.xxxxxxxxxxx.com/temp/"

OK
AT+HTTPACTION=0

OK

+HTTPACTION:1,200,56
AT+HTTPREAD

+HTTPREAD:56
{"type":"dOK

My function that reads characters as they come in:

void whileAvailable() {
  char data;
  while (SIM900.available()) {
    data=SIM900.read();
    if (data>0) Serial.print(data);
  }
}

I believe the function is reading characters fine however I am not sure why it is failing the find the rest of the characters

Although this may highly be a buffer overflow, it is NOT the only reason. The web site answering the request causes it also (the response headers). Most probably above code works for google.com.hk but not for your site. — karanis

goddland_16 goddland_16 · Accepted Answer · 2016-05-19T06:42:16

This is due to Serial buffer overflow of arduino uno or mega you use. Increase the buffer size so that they will accommodate more bytes; and those data can be displayed.

HTTPREAD missing characters with Arduino and SIM900

2 Answers