I'm getting Sim 808 init error

[deluxen123]

I recently bought a SIM 808 EVB-V3.2 module and I wanted to do a basic test.

I made use of an example code from the DFRobot_sim808.h library

From the following code I want to recieve a call from the sim 808 module

#include <DFRobot_sim808.h>
#include <SoftwareSerial.h>

#define PIN_TX    10
#define PIN_RX    11
SoftwareSerial mySerial(PIN_TX,PIN_RX);
DFRobot_SIM808 sim808(&mySerial);//Connect RX,TX,PWR,

//Mobile phone number,need to change
#define PHONE_NUMBER  "8116***186"   

//DFRobot_SIM808 sim808(&Serial);

void setup() {
  mySerial.begin(9600);
  Serial.begin(9600);
  //********Initialize sim808 module*************
  while(!sim808.init()) { 
      delay(1000);
      Serial.print("Sim808 init error\r\n");
  }
  Serial.println("Sim808 init success");
  Serial.println("Start to call ...");

  //*********Call specified number***************
  sim808.callUp(PHONE_NUMBER);
}
void loop() {
  //nothing to do
}

but when I run my program I am getting the "sim 808 init error"

I am powering the module with 9V 2A, and my connections are like this:

Physical connections:

I don't know why I am getting that error, the module seems it's recognizing the Sim card because the second led is blinking every 3 seconds.

Any suggestion would be very helpful

[horace]

have a look at car-tracking-system-with-the-sim808-module - it appears to show different Arduino <> SIM connections to your circuit

[deluxen123]

The connections are the same

pin 10(TX) -> RX
PIN 11(RX) -> TX

[horace]

I was looking at the diagram of the Mega which has pin connections 10 and 11 the other way around??
pin 11(TX) -> RX
PIN 10(RX) -> TX
maybe worth swopping the connections over?

[deluxen123]

I tried that and I'm getting the same

[horace]

maybe worth seeing if you can get basic AT commands to work with software-serial

check the voltages on Tx and Rx should be 5volts when idle

[deluxen123]

It was exactly the first thing I tried, I even made a post about that: Serial Terminal not working with AT commands - #11 by deluxen123

unfortunately I don't have a multimeter, but I tried to check the voltage with this little program:

float lectura;
float volt;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(A0,INPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  lectura = analogRead(A0);
  volt = lectura /1023 * 5.0;
  Serial.println(volt);

  delay(2000);
}

I got from both TX and RX 5 volts

I know that this is not the best way to measure the Voltage but this is all I've got

[horace]

The first thing I test with a modem is response to AT commands
If that fails you have problems, e.g. faulty modem, design or tracking error on new PCB, etc etc
if when you press the ON button LEDs light it clearly has power and a blinking LED indicates something is operational
I assume you tried different baud rates when testing AT commands

[deluxen123]

I tried with this program:

#include <SoftwareSerial.h>

SoftwareSerial softSerial(7, 8);  // Rx, Tx


uint32_t baud[] = {   
                       300,
                       600,
                      1200,
                      2400,
                      4800,
                      9600,
                     19200,
                     38400,
                     57600,
                     74880,
                    115200
                  };

void setup()
{

  Serial.begin(9600);
  
  for (uint8_t i = 0; i < sizeof(baud) / sizeof(baud[0]); i++)
  {
    softSerial.begin (baud[i]);
    
    Serial.print("Trying @ ");
    Serial.println(baud[i]);
    
    softSerial.println("AT"); 

    unsigned long start = millis();
      
    while (millis() - start < 500)
    {
      while (softSerial.available() > 0)
      {
        Serial.write(softSerial.read());
      }
    }
       
  }
}


void loop()
{}

and I got this

[deluxen123]

I was able to get basic AT commands to work with software serial!

I just added AT+IPR=9600 right before the loop

and now I'm getting a readible answer from the module

I even tried with a little program to introduce AT commands

#include <SoftwareSerial.h>
SoftwareSerial SIM808(7, 8); //Seleccionamos los pines 7 como Rx y 8 como Tx

void setup()
{
 SIM808.begin(9600);
 Serial.begin(9600);

 SIM808.println("AT+IPR=9600");

 delay(100);
}

void loop()
{
 //Envíamos y recibimos datos
 if (Serial.available() > 0)
 SIM808.write(Serial.read());
 if (SIM808.available() > 0)
 Serial.write(SIM808.read());
}

and it's working, I even was able to make a call to myself!