I need some advice for my smart home project regarding communication between 1 master arduino and multiple slave arduinos.
I want to reduce the use of WiFi connections from smart devices in my home (+- 200 of them) and rather use wired communication. For this I plan to use 1 master Arduino per room/function which connects to the central hub via an Ethernet LAN module & MQTT. All the +-20 devices within the room will be connected to the master. Most of the devices use the esp8266 module and have the pins TX, RX, GPI0, GND and V+ available which means I2C is not an available.
My thought is that the master should send all commands to all devices simultaneously, e.g. from TX master to each RX of all devices so that the devices are synchronized. BUT my master Arduino is limited in RX input pins and cant receive all the communication from the devices simultaneously this way. What options do I have?