2

I have a SIM800L module and I want to send SMS. But this module is not connect to network. I am from Sri Lanka.

I am using 3G SIM card and I think it is not issue because if it 3G SIM it can shift to 2G. Am I right? I put this SIM card to my iPhone and change setting to 2G then also get signals "E".

When SIM card is in the module and call to this SIM number(Module), it says Phone off. Not showing ring ring in AT terminal.

Signal LED also blinking faster not slowly.

Module

I get AT commands response. I tied following commands. 

AT+CSQ

+CSQ: 0,0

Thant means no signals but..

AT+COPS=?

Call Ready

SMS Ready

+COPS: (1,"Hutchison Lanka (Pvt)","Hutch","41308"),(3,"Mobitel","MOBITEL","41301"),(3,"CELLTEL INFINITI","CELLTEL","41303"),(3,"41305","41305","41305"),(1,"DIALOG","DIALOG","41302"),,(0-4),(0-2)

OK

I can get networks. My sim card is Hutch. That means Antenna also working fine right? How to check Antenna also (Specific bandwidth)? 

AT+CSCS?

+CSCS: "IRA"

OK

How to sole this problem? Is there have any AT command to set or check?

saji indra
  • 57
  • 1
  • 1
  • 9

3 Answers3

1

The CSQ command returning 0 means something is not right and you cannot ignore that. So that needs to be looked into.

To begin with, in your post you have provided the result of AT + COPS=? command. This will only give the list of available network operators. With this you cannot assume that your sim is actually registered to one of these operators. To know that, you can try AT + COPS? command. This will tell you with which network operator your sim is registered with. If this is not giving you the expected results, try AT + CREG? command and check the registration status of your sim. If the status is not 1, then do network registration by AT + CREG=1

Ramya Baladhandapani
  • 21
  • 4
0

I had exactly this same problem.

I found out the board was restarting usign this script:

import time, serial
s = serial.Serial('/dev/ttyUSB0')
while True:
    time.sleep(1)
    string_read = s.read(s.inWaiting())
    if string_read:
        print(string_read)

Each 6 or 7 seconds i got this output:

b'\x00'

Everywhere I read they said it was a power issue. So I bough a better converter with no success.

Then I realized I was using bad quality cables, and it didn't matter how much capacitance I put in the other end the issue continued.

What I finally did was getting good quality cables and solder them directly in the sim800l board.

Now the board is not restarting anymore

Alejo Dev
  • 2,290
  • 4
  • 29
  • 45
0

I soldered 1000 uF capacitor to VCC/GND pins and it helped to this problem. Firstly I was powering it with 4.2 V from 5A lab power supply, now it's powered frim LM2506 step down converter and still works.

Piotr Smarzyński
  • 23
  • 3