Introduction

This project has as final purpose, transmitting data over a long range, to a node which is an internet gate (in this case the ESP).

Hardware

Bill of materials (BOM)

- 1 x ESP32 WROVER KIT (in this case: T18 3.0)

- 2 x Arduino board (any, just to have SPI. In this case is Uno)

- 2 x nRF24L01 modules

- 1 x Sound sensor

- 1 x 9V battery

- wires

Schematic

Experimental setup

Description of the setup

1. nRF24L01+ PA + LNA

It is a low cost wireless communication module, created by Nordic Semiconductor. There are libraries written to provide API and easy compatibility with Arduino. It's range varies from 250m to 1100m. Maybe the most helpful feature is has is that the communication range can be traded-off with the data bandwidth. Possible combinations are: 2Mbps for 250 meters, 1Mbps for 500 meters, 250kbps for 1100 meters. It's frequency in the 2.4 GHz ISM band, or more precisely, any frequency between 2.400 and 2.525 GHz (2400 to 2525 MHz). Also one channel has a bandwidth of almost 1MHz, means that it gives us 125 possible channels with a 1MHz spacing.

PA stands for Power Amplifier and LNA stands for Low-Noise Amplifier its function is to amplify an extremely weak signal received from the antenna.

Also it is worth mentioning that one device can communicate up to 8 devices.

Software

Because the nRF24L01 module is using SPI communication, first step is to assure the ESP32 TTY board supports SPI communication and find out pins of this specific module board. Easy task, just run a small script to findout SPI pinouts: 'MISO', 'MOSI', 'SS', 'CLK'.