Using RFID-RC522 and GrovePi Sensors Simultaneously

Archives GrovePi
1

Hi,
I am currently trying to read data from this temperature sensor and read RFID-Cards at the same time. Therefore I also bought the RC522 Reader/Writer from joy-it. When I use them in separated scripts they work fine.
Scripts:

#!/usr/bin/env python

import RPi.GPIO as GPIO
import sys
sys.path.append('/home/pi/MFRC522-python')
from mfrc522 import SimpleMFRC522

reader = SimpleMFRC522()

print("Show your card")
try:
    id,text = reader.read()
    print(id)
    print(text)
finally:
    GPIO.cleanup()

import time
import grovepi

# Connect the Grove Temperature Sensor to analog port A0
# SIG,NC,VCC,GND
TEMP1_PIN = 0


while True:
    try:
        temp1 = round(grovepi.temp(TEMP1_PIN,'1.2'))
        print(temp1)
        time.sleep(2)

    except KeyboardInterrupt:
        break
    except IOError:
        print ("Error")

But when I try to read a RFID tag and and the sensor data in the same script:

#!/usr/bin/env python

import RPi.GPIO as GPIO
import sys
sys.path.append('/home/pi/MFRC522-python')
from mfrc522 import SimpleMFRC522
import time
import grovepi

TEMP1_PIN = 0

i = 0
while i<20:
    if i%2 == 0:
        try:
            temp1 = round(grovepi.temp(TEMP1_PIN,'1.2'))
            print(temp1)
        except KeyboardInterrupt:
            print("interrupted")
    else:
        try:
            print("Show Card")
            reader = SimpleMFRC522()
            id,text = reader.read()
            del reader
            print(id)
            print(text)
        finally:
            GPIO.cleanup()
    i += 1

they seem to block each other from reading. When I start the program the output is:

23
Show Card
718099397027
hallo

So what I made of this is, that without creating an SimpleMFRC522 object it is possible to read from the sensor. But after creating such an object it just freezes while trying to receive the data from the sensor. I tried to solve this by deleting the object after the card was read, but that didn’t help. I also tried to understand the exact reason on why this is happening, but I only found out that the RFID-Reader communicates via SPI and the GrovePi via I²C (or not?) and that these communications usually don’t interfere with each other, as they are using different ports of the Pi.

My question is, if anybody knows why exactly this happens and if there is a way to solve this problem.

Greetings Joe

note: I am sorry, if some of my formatting are not correct or not fitting for this forum. I am new to using a raspberryPi and GrovePi.

2

Update:
I couldn’t find a good soluition yet.
I found out, that if you I only create the reader object like this:

import RPi.GPIO as GPIO
import sys
sys.path.append('/home/pi/MFRC522-python')
from mfrc522 import SimpleMFRC522
import time
import grovepi

reader = SimpleMFRC522()

# Connect the Grove Temperature Sensor to analog port A0
# SIG,NC,VCC,GND
TEMP1_PIN = 0


while True:
    try:
        temp1 = round(grovepi.temp(TEMP1_PIN,'1.2'))
        print(temp1)
        time.sleep(2)

    except KeyboardInterrupt:
        break
    except IOError:
        print ("Error")

the script freezes when it is trying to get the temperature. Alternatives like grovepi.analogRead() are also not working. Importing a script in that I define the function to read an RFID card doesn’t solve the problem either.

The only option that ‘worked’, was writing a shell script that opens the two scripts seperately like this:

#!/bin/bash

cd /path/to/scripts

while [ 1 ]
do
    ./ReadRFID.py
    ./ReadTemperature.py
done

But I guess that is not really efficient.