错误：SIM900无法接听。检查GSM.cp中的电源和串行引脚

Question

iam使用带有Arduino Uno的itead sim908 Gsm / Gps / Gprs模块，iam尝试通过Sms消息和gprs向互联网服务器发送Gps坐标，但是无法同时运行它，虽然它可以单独工作。

当我尝试通过短信发送GPS坐标并通过gprs发送数据到同一时间我有这个错误：

  

错误：SIM900无法接听。检查GSM.cpp中的电源和串行引脚

这是我的代码，任何人都有解决方案吗？

#include "SIM900.h"
#include 
#include "inetGSM.h"
#include "sms.h"
//#include "call.h"
#include "gps.h"
char smsbuffer2[150];
char id[]="12";
char httpbuffer[160];

InetGSM inet;
//CallGSM call;
SMSGSM sms;
GPSGSM gps;
char msg[50];
int numdata;
char lon[15];
char lat[15];
char alt[15];
char time[20];
char vel[15];
char msg1[5];
char msg2[5];
char Mobile[]="0595285486";
char stat;
char inSerial[50];
int i=0;
boolean started=false;
void setup(){
get_gps();
delay(1000);
send_server();
delay(1000);
send_sms();
}
void loop(){
}
void get_gps(){
Serial.begin(9600);
Serial.println("GSM Shield testing.");
//Start configuration of shield with baudrate.
//For http uses is raccomanded to use 4800 or slower.

 if (gsm.begin(9600)) {
      Serial.println("\nstatus=READY");
      started=true;
       gsm.forceON();
 } else Serial.println("\nstatus=IDLE");

 if(started) {
      //GPS attach
      if (gps.attachGPS())

           Serial.println("status=GPSREADY");
      else Serial.println("status=ERROR");
      delay(20000); //Time for fixing
      stat=gps.getStat();
      if(stat==1)
           Serial.println("NOT FIXED");
      else if(stat==0)
           Serial.println("GPS OFF");
      else if(stat==2)
           Serial.println("2D FIXED");
      else if(stat==3)
           Serial.println("3D FIXED");
      delay(5000);
      //Get data from GPS
      gps.getPar(lon,lat,alt,time,vel);
      Serial.println(lon);
      Serial.println(lat);
      Serial.println(alt);
      Serial.println(time);
      Serial.println(vel);
      convert2Degrees(lat);
      convert2Degrees(lon);
 }
}
void send_server(){
if (gsm.begin(9600)) {
Serial.println("\nstatus=READY");
started=true;
} else Serial.println("\nstatus=IDLE");

    if(started) {

      //GPRS attach, put in order APN, username and password.
      //If no needed auth let them blank.
      if (inet.attachGPRS("internet", "", ""))
           Serial.println("status=ATTACHED");
      else Serial.println("status=ERROR");
      delay(1000);
      //Read IP address.
      gsm.SimpleWriteln("AT+CIFSR");
      delay(5000);
      //Read until serial buffer is empty.
      gsm.WhileSimpleRead();
      //TCP Client GET, send a GET request to the server and
      //save the reply.
      /*
              httpbuffer[0]='\0';
strcat(httpbuffer,"/GetData.aspx?lat=");
strcat(httpbuffer,lat);

strcat(httpbuffer,"&&lon=");
strcat(httpbuffer,lon);
strcat(httpbuffer,"&&id");
strcat(httpbuffer,id);

        Serial.println(httpbuffer);
*/
numdata=inet.httpPOST("qou.azurewebsites.net", 80,"httpbuffer", msg, msg,12);
//Print the results.
Serial.println("\nNumber of data received:");
Serial.println(numdata);
Serial.println("\nData received:");
Serial.println(msg);
}
}
void send_sms(){

 if (gsm.begin(9600)) {
      Serial.println("\nstatus=READY");
      started=true;
 } else Serial.println("\nstatus=IDLE");
if(started){

            smsbuffer2[0]='\0';
strcat(smsbuffer2,"Vehicle Accident Occurs to Vehicle which Have ");
strcat(smsbuffer2,"ID number");
strcat(smsbuffer2,id);
strcat(smsbuffer2,"in Location :");
strcat(smsbuffer2,lat);
strcat(smsbuffer2,lon);
strcat(smsbuffer2,"Owner Name:Ayman Abd Albasit Sadq Daqah");

strcat(smsbuffer2,"Mobile :");
strcat(smsbuffer2,Mobile);
if (sms.SendSMS(Mobile, "smsbuffer2"))
Serial.println("\nSMS sent OK");
}
}