SIM 800L Arduino NANO wake-up SMS

Hardware Nano Family Classic Nano
1

Hello together,

I am currently trying to develop a bee scale using an Arduino NANO, HX711 and for communication a SIM800L GSM module (the red one).

The problem is that I have already done this circuit and it works with an Arduino UNO but connected to the 12V power supply.

I want to take the circuit and make it OFF-GRID by using a 12V battery and a solar panel.

The problem which I am facing is how to put the GSM and the NANO into sleep mode in such a way that when the GSM is receiving an SMS to wake up the arduino also.

I already checked the datasheet of the GSM module and it states that with the serial command AT+CSCLK=1 the module will enter a sleep mode and after it will receive an SMS will wake up. This is clear until now. The problem is how can I wake up the NANO also by using this SMS?

How I see it function:

  1. NANO and GSM in Sleep mode
  2. GSM receives and SMS
  3. GSM wake-up the NANO (How I can do this?)
  4. NANO receives the SMS
  5. NANO does some measurements
  6. NANO send through serial the results
  7. GSM send this results to a phone number
  8. NANO and GSM goes back to sleep
  9. Rinse and repeat

Could you explain how can I do step 3? Can I wake an Arduino NANO on serial? Some kind of “Software Interrupt”?

Thanks in advance!

sim800l datasheet
sim800l datasheet1079×637 95.5 KB

2

if the SMS is automatically transferred using the Serial line to the host Arduino, then you could wake up on Serial. you'll likely loose the first byte but that could be accounted for in the SMS you send (and an extra char at the start of the message and then only the command - something like ">do this"

3

Hello J-M-L,

So if i put the NANO to sleep I can just send the SMS through serial and then the NANO will wake up? I am asking just to be sure.
There is a special command for this or?

Thanks in advance!

4

I've never done it with a SIM800 module
I know that upon receiving an SMS you can configure the module to spit out a message on the Serial line.
so IF the SIM800 module can be put to sleep (assume a light sleep where the radio still works otherwise you would not be receiving SMS) and can really be awoken by an incoming SMS then the data will get pushed to the Tx serial line.

if you configured the Rx line of your arduino to trigger an interrupt (for example using pin change interrupt) then your arduino will wake up and proceed from where you stopped it.

5

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