GSM SIM800L Some Problem

Hello Again
i Got GSM Sim800l Better Then i was have Sim900 Replyced A6
So GSM SIM800l is GOod ?!
he was works fine But now i got some Issue i Connect it to USB TO Serial
So when i Enter AT Commend some Problem Happend Like :


SMS Ready
+CMGR: 1,"",24


Call Ready

SMS Ready

Every time i enter " AT " he Replay Me
Call Ready

SMS Ready "
Why ?!
And Some time when i going to Read Massage


And SOme time when im going to Make Call


i got replay
what is Meen ?!! :slight_smile:
i hope u help me and Thanks

The SMS ready and Call ready URC appear on restarts. If you are getting them repeatedly the module might be restarting.
Make sure you have proper supply connected with 4V 2A sourcing capacity and also dont use 5V USB UART lines without voltage level translator with GSM module. It can also cause restarts when AT command are being tested on 5V lines.

i Connecting
TX Of GSM RX Of Serial to USB
Rx Of GSM TX Of Serial To USB
GND Of GSM GND Of Serial To uSB

GND GND Power Supply Out Source
5V Power Of Power-Supply Out Source

This is Correct Connecting
Or Whta u Meen Of " dont use 5V USB UART lines without voltage level translator with GSM module "
Thnx For Replaying ?!
This Module is Good ?!

Module is good. But Module UART lines run at 2.8V and Converters at 5V
They cant be connected directly. It will be over voltage for module UART lines.

Ok … thnx … so i will upload AT commend library on Arduino and work with GSM with AT commend Right ? that is Better ?!! And What the meen of " NO DIAL TONE"

Can u give me tut about how can i save number of Receive Sms to EEPROm ? and Call the number again to send sms ?! thnx

Even Arduino lines are at 5V. You need level translator in between. Connecting UART lines of arduino directly to module UART lines might damage them,

Right now i don’t have such a tutorial, will make in future soon.

Look in USB to Serial Convert Name " FT232"
i Saw 3 Pin " 5V - VCCIO - 3.3V " Was Jumber between " VCCIO / 3.3 V " So i wasn got Problem So i changed it to " 5V - VCCIO " And i think Now Work`s Fine … i didnt See any Restart of Module So im My Case now is Fine OR i Makeed Something Wrong when i Change this Jumber ? !

thnx For Your Replaying And Helping

Oh, I think VCCIO should be better at 3.3V. But still 3.3V is higher than 2.8V. But if you are not getting any problem then go ahead.

i Just Using USB to serial to Test GSM … so i will not using it Alot of time … Just For Testing so USB with Jumber 5V and VCCIO From Laptop And GSM Getting Power Supply From Out Side Laptop So it`s work fine and No problem will happened right ?!

Wherever you derive , the IO levels should not exceed. You might or might not damage the lines, But it depends on your luck. :slight_smile:

But its good to go by the books.

A post was split to a new topic: GPS tracker design - GSM power supply selection