I want to design an electronic safebox with 500 boxes or more. There is a central RFID reader in which every customer is given a tag. When the tag is approached to the reader, the relevant box will open. I thought I could use a reader for each box but this will become costly.
RS485 was another choice due to noise immunity and long range but it supports maximum 320 nodes:
In this scenario, a single reader is installed and all other locks are controlled via this protocol.
Wireless communication(Zigbee?) was another option but I am really afraid of using it due to high cost and complexity.
I2c again rejected as it supports 128 nodes. (AFAIK)
LAN connection? using a Wiznet W5100 and a a single attiny13a? Is it cheap and practical?
What do you think is the best option?