Is it possible to connect 4 or more Arduinos to a single GSM Module.? All the Arduinos need to send SMS at a specific time daily. How do I make sure thet don't time collide with each other, other than sending sms at different times for each Arduino?. I want the SMS to be queued up, and be sent one by one.

  • connect the GSM to only one arduino
    – jsotola
    Aug 20, 2020 at 2:53

1 Answer 1


You should consider connecting one Arduino to the GSM module, and connect the 4 Arduinos together using SPI, I2C, or any other inter-hardware comms protocol. Before I knew these options existed, I once wrote a bit of code to send data between Arduinos by having one pin represent the data being sent and another pin changing every time a new bit was available. You could do something similar with an extra line per pairing, so an Arduino could tell the primary that it had new data to send.

Anyway, check out the "Wire Library" - it's basically for this kind of work. I think you'll be happier trying to have one Arduino "in charge" and connected to the CSM while the rest vie for its attention.

  • At the risk of arguing with myself, give the SPI library a look-in as well. Depending upon the situation, SPI can be easier to work with. It's the simpler of the two protocols. Aug 21, 2020 at 16:29

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