Say a home IoT application to monitor water levels in basement at 4 or 5 different places and transmit that data back to a single Arduino board to be then interfaced with a GUI to do home monitoring?
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Yes this could be done using SPI (with separate slave select wires), i2c or daisy chained UART providing a wired solution.
Yes you can ... however, how you transmit the sensor data? If wireless, you need some RF communication, and possibly a microcontroller like Arduino (or ESP) within each sensor module.
With nRF24L01 (2.4GHz) you can use 6 'slaves' (sensor modules in your case) to send data to the master (monitoring module).
Do things one by one:
- First make one sensor module
- Than make the master to receive data
- Than make the GUI screen
- Than make the other five sensor modules