For university I have to connect multiple RFID readers to my RasPi. Ideally 8 at a time. However after weeks of testing I have not managed to make it work. I figured out that the setmode GPIO.BOARD allows me to talk to all the pins I want and set them high for example. But I have been unable to read any data from a RFID reader other then when the SDA is connected to pin 24. Any other pin even when declared in the script does not seem to work. I tried the script from Alex Berliner in this post, but without any luck. here
This is my current script which also does not seem to be working:
import RPi.GPIO as GPIO
from mfrc522 import MFRC522
import spidev
import time
class RFIDReader:
def init(self, rst_pin, cs_pin, spi_bus=0, spi_device=0):
self.rst_pin = rst_pin
self.cs_pin = cs_pin
self.spi_bus = spi_bus
self.spi_device = spi_device
GPIO.setup(rst_pin, GPIO.OUT)
print(rst_pin)
self.mfrc522 = MFRC522(self.spi_bus, self.spi_device, self.rst_pin, self.cs_pin)
def read(self):
print("reading: rst_pin")
(status, TagType) = self.mfrc522.MFRC522_Request(self.mfrc522.PICC_REQIDL)
if status == self.mfrc522.MI_OK:
(status, uid) = self.mfrc522.MFRC522_Anticoll()
if status == self.mfrc522.MI_OK:
uid_str = ".".join([str(i) for i in uid])
print(uid_str)
return uid_str
return None
Setup GPIO
GPIO.setmode(GPIO.BOARD)
Initialize readers
reader1 = RFIDReader(rst_pin=24, cs_pin=0) # CE0
reader2 = RFIDReader(rst_pin=26, cs_pin=1) # CE1
try:
while True:
uid1 = reader1.read()
if uid1:
print(f"Reader 1 detected UID: {uid1}")
uid2 = reader2.read()
if uid2:
print(f"Reader 2 detected UID: {uid2}")
time.sleep(0.1)
except KeyboardInterrupt:
GPIO.cleanup()
finally:
GPIO.cleanup()
I have another test script which also only reads from pin 24:
from mfrc522 import SimpleMFRC522
import RPi.GPIO as GPIO
import signal
import spidev
import sys
import time
class NFC():
def init(self, bus=0, device=0, spd=1000000):
self.reader = SimpleMFRC522()
self.close()
self.boards = {}
self.bus = bus
self.device = device
self.spd = spd
def reinit(self):
self.reader.READER.spi = spidev.SpiDev()
self.reader.READER.spi.open(self.bus, self.device)
self.reader.READER.spi.max_speed_hz = self.spd
self.reader.READER.MFRC522_Init()
def close(self):
self.reader.READER.spi.close()
def addBoard(self, rid, pin):
self.boards[rid] = pin
GPIO.setup(pin, GPIO.OUT)
print(pin)
print(self.boards)
def selectBoard(self, rid):
if not rid in self.boards:
print("readerid " + rid + " not found")
return False
#for loop_id in self.boards:
#GPIO.output(self.boards[loop_id], loop_id == rid)
return True
def read(self, rid):
if not self.selectBoard(rid):
return None
self.reinit()
rid, val = self.reader.read_no_block()
self.close()
return val
def write(self, rid, value):
if not self.selectBoard(rid):
return False
self.reinit()
self.reader.write_no_block(value)
self.close()
return True
clean up gpios on ctrl+c
def signal_handler(sig, frame):
GPIO.cleanup()
print()
sys.exit(0)
def main():
signal.signal(signal.SIGINT, signal_handler)
GPIO.setmode(GPIO.BOARD)
nfc = NFC()
readers = [
# rid, pin
("reader1", 24),
("reader2", 26),
]
for r in readers:
nfc.addBoard(r[0], r[1])
while True:
for r in readers:
try:
r_name = r[0]
if r[1] == 24:
GPIO.output(24, GPIO.LOW)
GPIO.output(26, GPIO.HIGH)
print("reading 24")
else:
GPIO.output(24, GPIO.HIGH)
GPIO.output(26, GPIO.LOW)
print("reading 26")
data = nfc.read(r_name)
if data:
print(f"{r_name}: {data}")
else:
print(f"No data from {r_name} {r[1]} detected")
except Exception as e:
print("e", e)
GPIO.cleanup()
if name == "main":
main()
I would really appreciate any help or hints why this is not working.
Wiring:
First MFRC522 Raspberry Pi Zero
---------------------------
VCC Pin 1 (3.3V)
GND Pin 6 (Ground)
RST Pin 22 (GPIO 25)
SDA Pin 24 (GPIO 8, CE0)
MOSI Pin 19 (GPIO 10)
MISO Pin 21 (GPIO 9)
SCK Pin 23 (GPIO 11)
Second MFRC522 Raspberry Pi Zero
VCC Pin 17 (3.3V)
GND Pin 20 (Ground)
RST Pin 15 (GPIO 22)
SDA Pin 26 (GPIO 7, CE1)
MOSI Pin 19 (GPIO 10)
MISO Pin 21 (GPIO 9)
SCK Pin 23 (GPIO 11)
