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Topic: Arduino plus few RFID (Read 144 times) previous topic - next topic

Wowas

Hi,

it is possible to connect few RFID readers to one Arduino?

I have Arduino Uno and RFID RC522, but I can buy something else if my components are not the best to do this.

johnwasser

The RFID RC522 uses the SPI interface.  All units will share the MOSI, MISO, and SCK pins but will each need their own SS and RST digital output pins.  Assuming the only other device you need is Serial you can fit seven RFID readers on an Arduino UNO.  You'll even have one pin to spare.  For example, one possible pin layout is:

13, 12, 11: Hardware SPI
10, 9: RFID 1  (10 is the hardware SS pin and must be an OUTPUT)
8, 7: RFID 2
6, 5: RFID 3
4, 3: RFID 4
1, 0: Serial
A0, A1: RFID 5
A2, A3: RFID 6
A4, A5: RFID 7
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Wowas

Thanks! I will check it today. So I need to for example connect together MOSI from RFID1 with MOSI from RFID2 and then connect it to MOSI on Arduino?

johnwasser

So I need to for example connect together MOSI from RFID1 with MOSI from RFID2 and then connect it to MOSI on Arduino?
Yes.  All of the slave devices use MOSI (Master Out/Slave In) to receive data from the Arduino and MISO (Master In/Slave Out) to send data to the Arduino.  They each have a separate SS (Slave Select) pin and only the slave whose SS pin is LOW talks to the Arduino.  The SCLK (Serial Clock) output provides signal clocking for whichever slave is selected.
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