Welcome in the forum!
1)The current range of RC522 RFID is around 3CM( a passive RFID). I need to improve the range of the RFID to at least 2m. Should I use a signal repeater or should I opt for a UHF reader?
That's a thing of antenna and HF, a matter I know nothing about.
2) How to interface multiple devices to the PSOC using same protocol and how should I handle priorities? The reader supports I2C, SPI and UART protocols.
A PSoC5 has got several interfaces, so that will not be a problem. How many do you need at the same time?
Priorities are handled automatically when using interrupts. Probably no conflict because the PSoC5 speed is comparably high.
The PSoC will be master in SPI or I2C communication, so you will have to poll your RFID slaves for something happening.
A UART connection could trigger the PSoC by a slave sending a byte to start a communication or just accepting the data. Though looking old fashioned, I would vote for UART. When the cables are longer than 1m I would suggest to use RS232 line drivers on both ends of the cable. This would be a star topology.
I2C is designed for shorter distances and I do not know if line drivers could extend the bus topology.
SPI bus could be extended using line drivers, but you will have probably some more wires in your cable to ss the different slaves
3) Time Stamping; Should I go for an internal timer or external clock?
There is an RTC component in the PSoC. That would require a setting of the current date/time at startup. When the system is running (more or less) continuously you might set that over hyperterm or PuTTY once a day. Needs a clock crystal 32768Hz.
Thanks for your input,
I want to handle two devices for now, and i want the devices to initiate the connection, else the PSOC will be in a continuous polling state until the reader picks up something. So I'll go for UART, since the doors will be at some considerable distance to the PSOC.
I'll look into RTC and come back.
As for the range, i'll try to utilize a battery powered tag so , it can be detected without additional hardware change, i hope.
Increasing the range could lead to the problem that the tag approaches the door and without passing through it is turned back.
i can solve that by making the plane of the door tangential to the max. detectable sphere.
How are you access the rfid? I am trying to use the adafruit API. I can read a card but having trouble writing to one.
Would love some advice if you don't mind? Did you write your own API or find one online?