I am on a team that is setting up an automatic irrigation system for a farmer. We are using an RFM95W by Adefruit to send information to a water source to shut off the water a mile or so away, along with some switches, sensors, LCDs, and relays, and all of this is connected to an ELAGOO MEGA 2560. One of the things we wanted to set up is a way for information to get sent to the farmer via SMS, and for the farmer to be able to send text messages to the Arduino to control the system (such as to shut it off). This is a rural area in northern Wisconsin.
The original plan was to use an Adefruit FONA 3G (Adafruit FONA 3G Cellular Breakout - American version [Without Free Ting Sim Card] : ID 2687 : $79.95 : Adafruit Industries, Unique & fun DIY electronics and kits) to send texts back and forth with the Arduino. It looked very simple to integrate with and there was an example code for it. We are on a time crunch here. However, I read that 3G and 2G services are being dropped by big cell phone services companies like TMobile, ATT, and Verizon, in the next year or two so we are opting to not use that. This leaves us with 4G LTE, however, I read on a Reddit post that it may be the case that Arduino cannot keep up with 4G LTE data transfer rates.
The TLDR of my question is this: Is it true that since 3G and 2G GSM is being dropped by cell phone services, that something like an Adefruit FONA 3G module would not work as an SMS solution for a MEGA 2560, and is it also true that Arduinos are too slow for 4G LTE?
bartosz1313:
The TLDR of my question is this: Is it true that since 3G and 2G GSM is being dropped by cell phone services,
Usually provider do not just switch off services without notifying their customers. So, I would check their web sites to see whether they issued any warnings and contact them directly. A short email to customer services cost you a couple of minutes of your time.
If this is important to your customer, design the system in a way that you can update it with a plug-in module for the mobile modem.
bartosz1313:
and is it also true that Arduinos are too slow for 4G LTE?
This is a question of how the system is set up. I suspect most of the heavy lifting will be done by a special LTE modem. If the data for the application is limited the LTE data rate does not matter too much. If you only send 10 bytes per second, the Arduino will only need to handle these 10 bytes per second.
The same is true for WiFi. There are many WiFi applications build with Arduinos even though most Arduinos cannot handle sustained >10Mbit/s.
I’ve been using SIM7600 modules for about a year - for exactly the same reasons as you.
They are generally a direct drop-in for the earlier 3G modules, but beware, they don’t support VoLTE voice channels. There are other very obscure differences that you may not use, but my SIM5320 code worked immediately on the 7600, then I checked what needed to be fine-tuned.
I suspect any speed limitations are a combination of the ‘serial’ interface to the modem, and the data throughput of the low-end Arduinos.
I'd write the code so whatever SMS hardware was independent of it. Well, actually I already did that. I figured that when the time came, the new functionality would be there. The rest of the code could turn out to be huge (Using a GUI?) Get it running with whatever you can get/use quickly. When the time runs out, swap out the hardware & driver code. And you are back up and running.