nRF24L01 is a wireless transceiver module that operates in the frequency of 2.4GHz, which falls under the ISM band and hence it is legal to use in almost all countries for engineering applications.
nRF24L01 – How It Works, Arduino Interface, Circuits, Codes
nRF24L01 – How It Works, Arduino Interface, Circuits, Codes
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NRF24L01 pinout - A Comprehensive Review of the NRF24L01 Module
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