Problem with sim800l

Hi guys,

I'm a student who is trying to make a simple project with arduino and a sim800l evb module.
I watched some videos on youtube to hunderstand the basic but i'm stuck cause my sim800l doesn't work.

I can't figure out wich is the ring of the chain that doesn't work, it could be a wrong supply or wiring, defective board, wrong sim plan or maybe the code; so i'm here to ask help.

The only things that i can see are:

  • the module's leds doesn't light up
  • the module heat up a little bit
  • if i give some at commands form serial monitor it does noting

This is what i have:

  • Arduino uno
  • Sim800L EVB
  • Powerbank 5V/3.4A
  • sim form thingsmobile

This is the wiring (board -> arduino):

  • 5VIN -> Powerbank
  • GND -> Powerbank
  • VDD -> 5V
  • TXD -> pin 2
  • RXD -> pin 3
  • GND -> GND
  • RST -> X

The tutorial video that i used is this: Impostare il modulo GSM SIM800L per utilizzarlo con Arduino - Video 563 - YouTube
It is an italian maker (i'm also italian) and it is pretty reliable, is not the first time that i use one of his video like reference.

If you need further informations tell me :slight_smile:

Thank to everyone :smiling_face_with_three_hearts:

A schematic, not a frizzy would help along with links to each of the hardware devices that show technical information. Be sure it shows all ground connections as you have wired it. You can disconnect everything and load the blink sketch into your arduino, if that works the Arduino is probably OK. It should not get warm.

Remember SIM800 is a 2G module, make sure your part of the planet still supports 2G operation.

This is an excellent tutorial and many posters to this forum have used it to get started.
https://lastminuteengineers.com/sim800l-gsm-module-arduino-tutorial/

I am a concerned about this information but I'm not clear about your connections to the sim800l

  • Powerbank 5V/3.4A
    This is the wiring (board -> arduino):
  • 5VIN -> Powerbank
  • GND -> Powerbank
  • VDD -> 5V

The referenced tutorial states

VCC supplies power for the module. This can be anywhere from 3.4V to 4.4 volts. Remember connecting it to 5V pin will likely destroy your module! It doesn’t even run on 3.3 V! An external power source like Li-Po battery or DC-DC buck converters rated 3.7V 2A would work.

Hi, thank you all for answering me so quickly :upside_down_face:

@gilshultz i'm sure that arduino is ok, i used it in another project some days ago.

@lastchancename this is what wiki say (i live in Italy):

@cattledog i have already see that site and it is done really good but that isn't my board, i have this one
homyl-1pcs-sim800l-gprs-gsm-module-con-antenna-ttl-seriale-microcontrollori
Form what i read this have a circuit that make the 5v suitable.

As schematic i followed the tutorial of the past link:


but without the capacitor cause i don't have it

Thanks for the clarification. I now understand more about the V2 module and understand the 5v power supply.

I am still unclear about the Vdd pin of the UART section. It appears that you have connected it to 5v. Many of the references found on the web for that board with a 5v Arduino show it as not connected.

This forum thread mentions the Vdd pin and talks about an internal connection to the module at 2.8v.
https://forum.arduino.cc/t/sim800l-sim800l-evb-v2-0-variations-and-wiring/505185/2

Try with Vdd not connected.

However, the lack of any blinking status lights is quite concerning and indicates to me some problem with the module.