Architecture
Solution Variants
The solution will have two variants:
Variant 1: Node-RED Low-code Platform
In the second variant each board will be connected to a Raspberry Pi or a personal computer and exchange data with the Node-RED low-code platform running on the computer. Node-RED will connect to a WiFi network and exchange data with the MQTT broker on the cloud which will exchange data with the mobile IoT app. In this there will be no data exchange with the IoT app over BLE hence the ESP32 circuit will not be required.
Variant 2: Inter-board Communication
The first variant will implement inter-board communication using either the UART or the LoRa protocol between the two Nanos, Pico and the ESP32. The ESP32 will be programmed to connect to a WiFi network and exchange data with the MQTT broker on the cloud which will exchange data with the mobile IoT app. The ESP32 will also be programmed to exchange data with the mobile app over BLE.
The diagram below illustrates both variants.
