Introduction
Applications for Radio Frequency Identification (RFID) technology are becoming more and more common, ranging from inventory management to security systems. The RC522 RFID Reader Module’s cost and simplicity of integration make it a popular component. You may build a reliable RFID-based project when you combine the flexible Raspberry Pi Pico with a microcontroller with strong processing capabilities and an intuitive development environment.
We’ll walk you through connecting the RC522 RFID Reader to a Raspberry Pi Pico in this tutorial. Regardless of your background—a student completing a project for class, or a hobbyist investigating new technologies—this comprehensive guide will assist you in configuring the hardware, installing required libraries, and writing the code to get your RFID reader up and running. By the end of this article, you will have a RFID system ready to be build your own requirements.
Hardware Requirements
Notice: There might be affiliate links to Amazon on this page. which implies that I may receive a tiny commission from the sale. This may be your way of indirectly assisting me. Regards- Raspberry Pi Pico (HERE)
- 0.96″ I2C OLED Display (HERE)
- Micro USB Cable (HERE)
- RC522 RFID with Card (HERE)
- Connecting Wires (HERE)
- Breadboard (HERE)
Software Requirements
- Thonny IDE (Download HERE)
- SSD1306 library code (Download HERE)
- OLED library code (All files are in the same folder)
- RC522 library code (All files are in the same folder)
RFID RC522 Module
. This module operates at a 13.56 MHz frequency, intended for reading and writing data to RFID tags. Based on the MFRC522 IC, it offers numerous functions suitable for a wide range of RFID applications. Operating at the globally permitted RFID communication frequency of 13.56 MHz, it supports ISO 14443A/MIFARE protocols and is compatible with various RFID tags and cards. The typical read range is up to 5 cm, depending on ambient conditions and antenna configuration.
RX522 module communicates with microcontrollers using SPI (Serial Peripheral Interface), guaranteeing dependable and quick data flow.
Energy-efficient design qualifies it for battery-powered applications. Anyone interested in learning more about RFID technology can benefit greatly from the RFID RC522 module. This low-cost, user-friendly microcontroller is compatible with popular microcontrollers, making it a great option for novice and seasoned developers alike. We’ll walk through how to connect the RC522 module to a Raspberry Pi Pico in the upcoming parts so you may use this technology for your own projects.
You can use RFID to build many applications, such as access control, attendance systems, and inventory management. In the local market, you will get mainly two types of RFID readers. One with SPI communication and the other one with serial communication.
In this tutorial we will use RC522 RFID Module.
The RC522 RFID reader typically comes with an RFID card and a key tag. It stores the tag message or tag ID in its 1KB memory. The RC522 RFID module creates an electromagnetic field at 13.6MHz to communicate with the tag or card, transmitting and receiving data. You can interface this RFID with any microcontroller, including PIC, AVR, Arduino, and Raspberry Pi, via SPI. The SPI type of UART communication protocol uses four wires, and in SPI mode, it can connect with the host at up to 10Mbps.
RC522 RFID module pinout
RC522 Pin description
- SDA and SCL are the data and clock pins.
- SS, SCK, MOSI, & MISO are the SPI communication pins.
- TX & RX are UART pins for serial communication.
- GND pin is the common ground pin and it is connected with the GND pin of Raspberry Pi Pico.
- RST is the reset pin of the module.
- VCC pin is a 3.3v supply pin of the module needed to connect with the 3.3v VCC pin of Raspberry Pi Pico.
Circuit Diagram
Circuit Explanation
To build the circuit as shown in the circuit diagram and please follow the below table for Raspberry Pi Pico and RC522 RFID modules.
| RC522 Module | Raspberry Pi Pico |
| SS | GP5 |
| SCK | GP2 |
| MOSI | GP7 |
| MISO | GP4 |
| IRQ | NC |
| GND | GND |
| RST | GP18 |
| VCC | 3.3v |
Now please follow the below table for connection between Raspberry Pi Pico and 0.96″ OLED display modules.
| OLED Module | Raspberry Pi Pico |
| SCL | GP17 |
| SDA | GP16 |
| VCC | 5v |
| GND | GND |
Source Code
To make the process easier to understand, the source code has been divided up into four different parts. Please follow the steps one after another to get the best result.
- The SSD1306 library code
- The OLED library code.
- The RC522 library code.
- The main code that runs and checks the authentication
SSD1306 library code
Now create a new file in the thony IDE and copy the below code and paste all the code in the new file and then save the file as ssd1306.py file in the Raspberry Pi Pico board memory.
import time
# import framebuf
try:
import framebuf
except:
def const(x): return x
# register definitions
SET_CONTRAST = const(0x81)
SET_ENTIRE_ON = const(0xa4)
SET_NORM_INV = const(0xa6)
SET_DISP = const(0xae)
SET_MEM_ADDR = const(0x20)
SET_COL_ADDR = const(0x21)
SET_PAGE_ADDR = const(0x22)
SET_DISP_START_LINE = const(0x40)
SET_SEG_REMAP = const(0xa0)
SET_MUX_RATIO = const(0xa8)
SET_COM_OUT_DIR = const(0xc0)
SET_DISP_OFFSET = const(0xd3)
SET_COM_PIN_CFG = const(0xda)
SET_DISP_CLK_DIV = const(0xd5)
SET_PRECHARGE = const(0xd9)
SET_VCOM_DESEL = const(0xdb)
SET_CHARGE_PUMP = const(0x8d)
class SSD1306:
def __init__(self, width, height, external_vcc):
self.width = width
self.height = height
self.external_vcc = external_vcc
self.pages = self.height // 8
# Note the subclass must initialize self.framebuf to a framebuffer.
# This is necessary because the underlying data buffer is different
# between I2C and SPI implementations (I2C needs an extra byte).
self.poweron()
self.init_display()
def init_display(self):
for cmd in (
SET_DISP | 0x00, # off
# address setting
SET_MEM_ADDR, 0x00, # horizontal
# resolution and layout
SET_DISP_START_LINE | 0x00,
SET_SEG_REMAP | 0x01, # column addr 127 mapped to SEG0
SET_MUX_RATIO, self.height - 1,
SET_COM_OUT_DIR | 0x08, # scan from COM[N] to COM0
SET_DISP_OFFSET, 0x00,
SET_COM_PIN_CFG, 0x02 if self.height == 32 else 0x12,
# timing and driving scheme
SET_DISP_CLK_DIV, 0x80,
SET_PRECHARGE, 0x22 if self.external_vcc else 0xf1,
SET_VCOM_DESEL, 0x30, # 0.83*Vcc
# display
SET_CONTRAST, 0xff, # maximum
SET_ENTIRE_ON, # output follows RAM contents
SET_NORM_INV, # not inverted
# charge pump
SET_CHARGE_PUMP, 0x10 if self.external_vcc else 0x14,
SET_DISP | 0x01): # on
self.write_cmd(cmd)
self.fill(0)
self.show()
def poweroff(self):
self.write_cmd(SET_DISP | 0x00)
def contrast(self, contrast):
self.write_cmd(SET_CONTRAST)
self.write_cmd(contrast)
def invert(self, invert):
self.write_cmd(SET_NORM_INV | (invert & 1))
def show(self):
x0 = 0
x1 = self.width - 1
if self.width == 64:
# displays with width of 64 pixels are shifted by 32
x0 += 32
x1 += 32
self.write_cmd(SET_COL_ADDR)
self.write_cmd(x0)
self.write_cmd(x1)
self.write_cmd(SET_PAGE_ADDR)
self.write_cmd(0)
self.write_cmd(self.pages - 1)
self.write_framebuf()
def fill(self, col):
self.framebuf.fill(col)
def pixel(self, x, y, col):
self.framebuf.pixel(x, y, col)
def scroll(self, dx, dy):
self.framebuf.scroll(dx, dy)
def text(self, string, x, y, col=1):
self.framebuf.text(string, x, y, col)
class SSD1306_I2C(SSD1306):
def __init__(self, width, height, i2c, addr=0x3c, external_vcc=False):
self.i2c = i2c
self.addr = addr
self.temp = bytearray(2)
# Add an extra byte to the data buffer to hold an I2C data/command byte
# to use hardware-compatible I2C transactions. A memoryview of the
# buffer is used to mask this byte from the framebuffer operations
# (without a major memory hit as memoryview doesn't copy to a separate
# buffer).
self.buffer = bytearray(((height // 8) * width) + 1)
self.buffer[0] = 0x40 # Set first byte of data buffer to Co=0, D/C=1
self.framebuf = framebuf.FrameBuffer1(memoryview(self.buffer)[1:], width, height)
super().__init__(width, height, external_vcc)
def write_cmd(self, cmd):
self.temp[0] = 0x80 # Co=1, D/C#=0
self.temp[1] = cmd
self.i2c.writeto(self.addr, self.temp)
def write_framebuf(self):
# Blast out the frame buffer using a single I2C transaction to support
# hardware I2C interfaces.
self.i2c.writeto(self.addr, self.buffer)
def poweron(self):
pass
class SSD1306_SPI(SSD1306):
def __init__(self, width, height, spi, dc, res, cs, external_vcc=False):
self.rate = 10 * 1024 * 1024
dc.init(dc.OUT, value=0)
res.init(res.OUT, value=0)
cs.init(cs.OUT, value=1)
self.spi = spi
self.dc = dc
self.res = res
self.cs = cs
self.buffer = bytearray((height // 8) * width)
self.framebuf = framebuf.FrameBuffer1(self.buffer, width, height)
super().__init__(width, height, external_vcc)
def write_cmd(self, cmd):
self.spi.init(baudrate=self.rate, polarity=0, phase=0)
self.cs.high()
self.dc.low()
self.cs.low()
self.spi.write(bytearray([cmd]))
self.cs.high()
def write_framebuf(self):
self.spi.init(baudrate=self.rate, polarity=0, phase=0)
self.cs.high()
self.dc.high()
self.cs.low()
self.spi.write(self.buffer)
self.cs.high()
def poweron(self):
self.res.high()
time.sleep_ms(1)
self.res.low()
time.sleep_ms(10)
self.res.high()OLED library code
Now oled library can be install from Thonny IDE. Please follow the procedure.
Open Thonny IDE go to Tools then got to Manage Packages and search “oled” for the library find the “micropython-oled” library from the search items by the author: Yeison Cardona and you can find an Install button below. Now just click on install button and install it. It will be installed inside the Raspberry Pi Pico automatically. So, no need to check, It will work.
RC522 library code
Now again create a new file and copy the below code and paste the code in the new file and save the file as a mfrc522.py file in the Raspberry Pi Pico board memory.
from machine import Pin, SPI
from os import uname
class MFRC522:
DEBUG = False
OK = 0
NOTAGERR = 1
ERR = 2
REQIDL = 0x26
REQALL = 0x52
AUTHENT1A = 0x60
AUTHENT1B = 0x61
PICC_ANTICOLL1 = 0x93
PICC_ANTICOLL2 = 0x95
PICC_ANTICOLL3 = 0x97
def __init__(self, sck, mosi, miso, rst, cs,baudrate=1000000,spi_id=0):
self.sck = Pin(sck, Pin.OUT)
self.mosi = Pin(mosi, Pin.OUT)
self.miso = Pin(miso)
self.rst = Pin(rst, Pin.OUT)
self.cs = Pin(cs, Pin.OUT)
self.rst.value(0)
self.cs.value(1)
board = uname()[0]
if board == 'WiPy' or board == 'LoPy' or board == 'FiPy':
self.spi = SPI(0)
self.spi.init(SPI.MASTER, baudrate=1000000, pins=(self.sck, self.mosi, self.miso))
elif (board == 'esp8266') or (board == 'esp32'):
self.spi = SPI(baudrate=100000, polarity=0, phase=0, sck=self.sck, mosi=self.mosi, miso=self.miso)
self.spi.init()
elif board == 'rp2':
self.spi = SPI(spi_id,baudrate=baudrate,sck=self.sck, mosi= self.mosi, miso= self.miso)
else:
raise RuntimeError("Unsupported platform")
self.rst.value(1)
self.init()
def _wreg(self, reg, val):
self.cs.value(0)
self.spi.write(b'%c' % int(0xff & ((reg << 1) & 0x7e)))
self.spi.write(b'%c' % int(0xff & val))
self.cs.value(1)
def _rreg(self, reg):
self.cs.value(0)
self.spi.write(b'%c' % int(0xff & (((reg << 1) & 0x7e) | 0x80)))
val = self.spi.read(1)
self.cs.value(1)
return val[0]
def _sflags(self, reg, mask):
self._wreg(reg, self._rreg(reg) | mask)
def _cflags(self, reg, mask):
self._wreg(reg, self._rreg(reg) & (~mask))
def _tocard(self, cmd, send):
recv = []
bits = irq_en = wait_irq = n = 0
stat = self.ERR
if cmd == 0x0E:
irq_en = 0x12
wait_irq = 0x10
elif cmd == 0x0C:
irq_en = 0x77
wait_irq = 0x30
self._wreg(0x02, irq_en | 0x80)
self._cflags(0x04, 0x80)
self._sflags(0x0A, 0x80)
self._wreg(0x01, 0x00)
for c in send:
self._wreg(0x09, c)
self._wreg(0x01, cmd)
if cmd == 0x0C:
self._sflags(0x0D, 0x80)
i = 2000
while True:
n = self._rreg(0x04)
i -= 1
if ~((i != 0) and ~(n & 0x01) and ~(n & wait_irq)):
break
self._cflags(0x0D, 0x80)
if i:
if (self._rreg(0x06) & 0x1B) == 0x00:
stat = self.OK
if n & irq_en & 0x01:
stat = self.NOTAGERR
elif cmd == 0x0C:
n = self._rreg(0x0A)
lbits = self._rreg(0x0C) & 0x07
if lbits != 0:
bits = (n - 1) * 8 + lbits
else:
bits = n * 8
if n == 0:
n = 1
elif n > 16:
n = 16
for _ in range(n):
recv.append(self._rreg(0x09))
else:
stat = self.ERR
return stat, recv, bits
def _crc(self, data):
self._cflags(0x05, 0x04)
self._sflags(0x0A, 0x80)
for c in data:
self._wreg(0x09, c)
self._wreg(0x01, 0x03)
i = 0xFF
while True:
n = self._rreg(0x05)
i -= 1
if not ((i != 0) and not (n & 0x04)):
break
return [self._rreg(0x22), self._rreg(0x21)]
def init(self):
self.reset()
self._wreg(0x2A, 0x8D)
self._wreg(0x2B, 0x3E)
self._wreg(0x2D, 30)
self._wreg(0x2C, 0)
self._wreg(0x15, 0x40)
self._wreg(0x11, 0x3D)
self.antenna_on()
def reset(self):
self._wreg(0x01, 0x0F)
def antenna_on(self, on=True):
if on and ~(self._rreg(0x14) & 0x03):
self._sflags(0x14, 0x03)
else:
self._cflags(0x14, 0x03)
def request(self, mode):
self._wreg(0x0D, 0x07)
(stat, recv, bits) = self._tocard(0x0C, [mode])
if (stat != self.OK) | (bits != 0x10):
stat = self.ERR
return stat, bits
def anticoll(self,anticolN):
ser_chk = 0
ser = [anticolN, 0x20]
self._wreg(0x0D, 0x00)
(stat, recv, bits) = self._tocard(0x0C, ser)
if stat == self.OK:
if len(recv) == 5:
for i in range(4):
ser_chk = ser_chk ^ recv[i]
if ser_chk != recv[4]:
stat = self.ERR
else:
stat = self.ERR
return stat, recv
def PcdSelect(self, serNum,anticolN):
backData = []
buf = []
buf.append(anticolN)
buf.append(0x70)
#i = 0
###xorsum=0;
for i in serNum:
buf.append(i)
#while i<5:
# buf.append(serNum[i])
# i = i + 1
pOut = self._crc(buf)
buf.append(pOut[0])
buf.append(pOut[1])
(status, backData, backLen) = self._tocard( 0x0C, buf)
if (status == self.OK) and (backLen == 0x18):
return 1
else:
return 0
def SelectTag(self, uid):
byte5 = 0
#(status,puid)= self.anticoll(self.PICC_ANTICOLL1)
#print("uid",uid,"puid",puid)
for i in uid:
byte5 = byte5 ^ i
puid = uid + [byte5]
if self.PcdSelect(puid,self.PICC_ANTICOLL1) == 0:
return (self.ERR,[])
return (self.OK , uid)
def tohexstring(self,v):
s="["
for i in v:
if i != v[0]:
s = s+ ", "
s=s+ "0x{:02X}".format(i)
s= s+ "]"
return s
def SelectTagSN(self):
valid_uid=[]
(status,uid)= self.anticoll(self.PICC_ANTICOLL1)
#print("Select Tag 1:",self.tohexstring(uid))
if status != self.OK:
return (self.ERR,[])
if self.DEBUG: print("anticol(1) {}".format(uid))
if self.PcdSelect(uid,self.PICC_ANTICOLL1) == 0:
return (self.ERR,[])
if self.DEBUG: print("pcdSelect(1) {}".format(uid))
#check if first byte is 0x88
if uid[0] == 0x88 :
#ok we have another type of card
valid_uid.extend(uid[1:4])
(status,uid)=self.anticoll(self.PICC_ANTICOLL2)
#print("Select Tag 2:",self.tohexstring(uid))
if status != self.OK:
return (self.ERR,[])
if self.DEBUG: print("Anticol(2) {}".format(uid))
rtn = self.PcdSelect(uid,self.PICC_ANTICOLL2)
if self.DEBUG: print("pcdSelect(2) return={} uid={}".format(rtn,uid))
if rtn == 0:
return (self.ERR,[])
if self.DEBUG: print("PcdSelect2() {}".format(uid))
#now check again if uid[0] is 0x88
if uid[0] == 0x88 :
valid_uid.extend(uid[1:4])
(status , uid) = self.anticoll(self.PICC_ANTICOLL3)
#print("Select Tag 3:",self.tohexstring(uid))
if status != self.OK:
return (self.ERR,[])
if self.DEBUG: print("Anticol(3) {}".format(uid))
if self.MFRC522_PcdSelect(uid,self.PICC_ANTICOLL3) == 0:
return (self.ERR,[])
if self.DEBUG: print("PcdSelect(3) {}".format(uid))
valid_uid.extend(uid[0:5])
# if we are here than the uid is ok
# let's remove the last BYTE whic is the XOR sum
return (self.OK , valid_uid[:len(valid_uid)-1])
#return (self.OK , valid_uid)
def auth(self, mode, addr, sect, ser):
return self._tocard(0x0E, [mode, addr] + sect + ser[:4])[0]
def authKeys(self,uid,addr,keyA=None, keyB=None):
status = self.ERR
if keyA is not None:
status = self.auth(self.AUTHENT1A, addr, keyA, uid)
elif keyB is not None:
status = self.auth(self.AUTHENT1B, addr, keyB, uid)
return status
def stop_crypto1(self):
self._cflags(0x08, 0x08)
def read(self, addr):
data = [0x30, addr]
data += self._crc(data)
(stat, recv, _) = self._tocard(0x0C, data)
return stat, recv
def write(self, addr, data):
buf = [0xA0, addr]
buf += self._crc(buf)
(stat, recv, bits) = self._tocard(0x0C, buf)
if not (stat == self.OK) or not (bits == 4) or not ((recv[0] & 0x0F) == 0x0A):
stat = self.ERR
else:
buf = []
for i in range(16):
buf.append(data[i])
buf += self._crc(buf)
(stat, recv, bits) = self._tocard(0x0C, buf)
if not (stat == self.OK) or not (bits == 4) or not ((recv[0] & 0x0F) == 0x0A):
stat = self.ERR
return stat
def writeSectorBlock(self,uid, sector, block, data, keyA=None, keyB = None):
absoluteBlock = sector * 4 + (block % 4)
if absoluteBlock > 63 :
return self.ERR
if len(data) != 16:
return self.ERR
if self.authKeys(uid,absoluteBlock,keyA,keyB) != self.ERR :
return self.write(absoluteBlock, data)
return self.ERR
def readSectorBlock(self,uid ,sector, block, keyA=None, keyB = None):
absoluteBlock = sector * 4 + (block % 4)
if absoluteBlock > 63 :
return self.ERR, None
if self.authKeys(uid,absoluteBlock,keyA,keyB) != self.ERR :
return self.read(absoluteBlock)
return self.ERR, None
def MFRC522_DumpClassic1K(self,uid, Start=0, End=64, keyA=None, keyB=None):
for absoluteBlock in range(Start,End):
status = self.authKeys(uid,absoluteBlock,keyA,keyB)
# Check if authenticated
print("{:02d} S{:02d} B{:1d}: ".format(absoluteBlock, absoluteBlock//4 , absoluteBlock % 4),end="")
if status == self.OK:
status, block = self.read(absoluteBlock)
if status == self.ERR:
break
else:
for value in block:
print("{:02X} ".format(value),end="")
print(" ",end="")
for value in block:
if (value > 0x20) and (value < 0x7f):
print(chr(value),end="")
else:
print('.',end="")
print("")
else:
break
if status == self.ERR:
print("Authentication error")
return self.ERR
return self.OKFinal Source Code
Now create a new file and copy the below code and paste the code in the file as main.py in the Raspberry Pi Pico board memory. Here we have saved the file as main.py this is to run the code automatically on raspberry pi pico bootup.
from machine import Pin, I2C
from mfrc522 import MFRC522
import utime
from ssd1306 import SSD1306_I2C
from oled import Write, GFX, SSD1306_I2C
from oled.fonts import ubuntu_mono_15, ubuntu_mono_20
rfid_reader = MFRC522(spi_id=0,sck=2,miso=4,mosi=7,cs=5,rst=18)
WIDTH = 128 # oled display width
HEIGHT = 64 # oled display height
i2c = I2C(0, scl=Pin(17), sda=Pin(16), freq=200000) # Init I2C using pins GP8 & GP9 (default I2C0 pins)
display = SSD1306_I2C(WIDTH, HEIGHT, i2c) # Init oled display
fontSize20 = Write(display, ubuntu_mono_20)
while True:
rfid_reader.init()
display.fill(0)
fontSize20.text("RC522", 40, 0)
display.text("Interfacing", 25, 22)
(card_status, card_type) = rfid_reader.request(rfid_reader.REQIDL)
if card_status == rfid_reader.OK:
(card_status, card_id) = rfid_reader.SelectTagSN()
if card_status == rfid_reader.OK:
rfid_card = int.from_bytes(bytes(card_id),"little",False)
if rfid_card == 1497986713:
display.text("Access",40,40)
display.text("Accepted",36,50)
elif rfid_card == 540378515:
display.text("Access",40,40)
display.text("Denied",40,50)
else:
print("Detected Card : "+ str(rfid_card))
display.show()
utime.sleep(1)
