Switching on/off SIM800L module from Arduino Nano

Using Arduino Motors, Mechanics, Power and CNC
1

Hi,

I need to switch on and off the power supply of a SIM800L module from an Arduino Nano.
SIM800L has an independant power supply (4,3 V - 2 A) from the arduino, but I am using common grounds. Most of the time the module will be off.
It is for a portable project so I need a low power solution.

What would be the best idea ?

  • Transistor/MOSFET ? I need at least a 3A one I guess so is it the best thing to do ?
  • A small 5V relay with >2A capability ? Is it possible with a low power coil ?
  • Optocoupler ?

What would be the best idea ?

Thanks for help :slight_smile:

Alex

2

Does you module support sleep mode?

3

No it doesn't.

I really need to switch off the power going to the module.

4

AlexBZH:
No it doesn't.

yes it does, with AT+CFUN=0, the module goes in flight mode, pulling less than 0.5mA , assume you have on board LEDs scrapped off

on the contrary using Transistor/MOSFET, think of the:

a. quiescent current

b. voltage drop across those switchers when engaged,

5

@KASSIMSAMJI yes actually you are right.

The thing is with AT+CFUN the module is going in flight mode and then wakes up after a few minutes.

6

Some info from the datasheet for the Sim800L

“4.3. Power Saving Mode
SIM800L has two power saving modes: Minimum functionality mode and sleep mode. AT command “AT+CSCLK=1”can be used to set SIM800L into sleep mode. AT command “AT+CFUN=“ can be used to set SIM800L into minimum functionality. When SIM800L is in sleep mode and minimum functionality mode, the current of module is lowest.
4.3.1. Minimum Functionality Mode
There are three functionality modes, which could be set by AT command “AT+CFUN=“. The command provides the choice of the functionality levels =0,1,4.
AT+CFUN=0: Minimum functionality.
AT+CFUN=1: Full functionality (default).
AT+CFUN=4: Flight mode (disable RF function).

AT+CFUN=0 is 0.796mA in sleep mode.

Minimum functionality mode minimizes the current consumption to the lowest level. If SIM800L is set to minimum functionality by “AT+CFUN=0”, the RF function and SIM card function will be disabled. In this case, the serial port is still accessible, but all AT commands correlative to RF function and SIM card function will not be accessible.“

Hope this helps.

7

It does I am going to try these different modes.

Thanks a lot.