Power toggle sim800L Module

I want to toggle sim800L module power using atmega328 how can I do that …

I am using in my project
sim800L module
Two batteries 18650 battery …

I am able to toggle HC-SR04,and I want to toggle GSM module for Power saving…

I use and try all sleep mode of sim 800L Module…
For saving battery life only option toggle 800L…

If you want tor remove power for module you need to use a Power MOSFET and control the power line by MCU.

Otherwise use the PWRKEY pin and observe GSM_STATUS pin to see if module is ON or OFF.

Hello Ravi

Have you do that, because i am not understood how I do in sim800L module…

Can you please share procedure

and operating voltage module is 3.4 to 4.4 volt and 18650 battery voltage is 4 volt that means we have only 0.7 volt for working right ?

What i am saying is pull the PWRKEY pin to GND to turn ON or turn OFF the module. If its on, it will become OFF. If its OFF it will turn ON.
To know whether the module is ON or OFF right now, you need to read the IO pin GSM_STATUS using a MCU.
If its HIGH then the GSM is ON and now if you pull PWRKEY pin LOW, it will turn off the module.

Yes all Lithium battery have that range and it takes lot of time to drop that 0.7V. Its good enough.

Thanks for replaying Ravi

But I am using this Module (Please check this image ) In This module I am unable to find power key. Please let me know where is power key or I am missing some thing.


You don’t have this pinout. There is for another board.

Hello Ravi

you are using the same module as I see on youtube so as per ALEXIS says there is no power key so how you manage power on and off of the module ???

Hi Sonu,
I use SIM800C and it has PWRKEY pin. SIM800L also has but it is below the module. SIM800C has pins outside on the edges. Your module also has but they are not accessible. But i think your breakout board might have them drawn out, you need to check the manufacturers manual for the pin out.

sir in SIM800L POWERKEY which transistor are used? and why are the used transistor in POWERKEY? Tx and Rx which transistor are used?
in SIM800L Rx and Tx TTL logic in the circuit, what is VDD?what are the uses VDD?

A BC547 transistor is used for the powerkey circuit in SIM800L?

You can use BC547 for PWRKEY pin.

For TX RX logic level translation i use TXS0102

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hello sir,

thank you, reply me. one more doubt sir, please tell me SIM800L VBAT connection and TX and RX connection circuit details? please, sir.

I dont understand your question?
There are lot of connection diagrams available with module manufacturer. What exactly you want me to provide?

Is there any firmware required for SIM800L or it is preloaded?

ESP8266-01 can we program it through wifi?

@sf750086 Please post your query in particular category.

Yes, All GSM module firmware pre-programmed. However there might be firmware update is needed if your GSM module has older firmware version. Some commands might not work with older firmware.

You can check this this tutorial.



(Please post your query in particular category.) sure sir,
and thank you sir.

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Is there requirement of switch for power key in SIM800L? and if it requires how it connect. please share a component and circuit for that.?

The connection to PWRKEY is given in datasheet. Use the same.
FIrst check if your module provider has left PWRKEY pin out. If yes then just use the transistor circuit given in hardware design guide of SIM800L. Google and you will find this doc.