Questions tagged [rfid]

Radio Frequency IDentification

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Reading multiple RFID tags within 1m range [closed]

Hello Community and RFID Enthusiasts, Could you recommend me an RFID system with the capability to read and track multiple (10-20) RFID tags simultaneously within a range of 0-120cm? My understanding ...
Barnabás Várszegi's user avatar
3 votes
3 answers
157 views

RFID PCB coil output power much lower than expected

I'm working on a PCB for RFID reading and writing however after assembling the PCB I have noticed the output field strength of the RFID coil is much lower than I anticipated. I was trying to copy the ...
Swiss Gnome's user avatar
1 vote
1 answer
65 views

ESP32-S3 SPI pins?

I am a beginner in electronics and tried to use ESP32-S3 for interfacing RFID and unable to find SPI pins in the the data-sheets. Tried Googling for pin reference but after reading so many blogs and ...
Sukhdarshan Vinayak's user avatar
1 vote
1 answer
52 views

External circuit to increase the series capacitance of a resonant circuit

I am working with a long-range reader and antenna coil for a low frequency (135 kHz) RFID application (please see the basic representation below.) The reader features some unknown source impedance, as ...
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How do I connect two RFID readers at the same time to my Arduino?

I’m making a simple door lock for my room using an Arduino uno and an RFID sensor, I made the code to unlock the door with the correct tag, but it’s only on one side, I need a way to unlock the door ...
Computer Noob's user avatar
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Can I use ultrasonic sensors to measure the distance from one specific object, in amongst other objects?

Basically, I am trying to design a modernised boule game whereby the tossed boule can automatically measure its distance from the jack via ultrasonic sensors positioned within the tossed boule, with ...
eutectic_bollock's user avatar
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MUX for RFID 13.56Mhz

Working on a project that involves an array of RFID (HF 13.56Mhz) antennas using a single RFID transceiver. In-order to switch between the antennas I'm looking for a 1:8 (or more) RF MUX. As the ...
Gilad's user avatar
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1 answer
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NFC antenna design / Simulation

I'm looking for help with my NFC (13.56MHz) antenna design. I am using a NXP-NT3H2111 NFC IC and so far I have read through the application note and other research papers available online to try ...
Ethan25's user avatar
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Receive Antenna Design Consideration in Dual Antenna LF RFID System

I am working on constructing a loop antenna pair for an LF RFID application. The antenna is quite large (4' x 6'). I was able to successfully wind a transmit (Tx) antenna and tune it such that it ...
tomhebe's user avatar
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Effective solution to detect objects on a board with "Positions and IDs"? (RFID, Capcitve Sensor touch, Optical Sensors, NFC, Magnetic Sensors)?

I have a board comprised of electromagnets array, to drive certain objects having magnets attached to them on its surface. Using a microcontroller I plan to move those objects by switching the ...
Kush_Uttam's user avatar
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RSSI measurement tool for RFID tag

I am building a prototype to measure the RSSI strength of RFID tags to get the signal strength. I tried looking for different kinds of readers but they only measure the presence of RFID tags but not ...
Abhishek Kumar's user avatar
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1 answer
90 views

SRIX4K Emulator - ASK transceiver

I'm trying to build a simple SRIX4K emulator using an ATMEGA328p, I found this circuit on the internet, and it should work as a simple ASK transceiver, using the MCU to transfer data using the SRIX4K ...
Giovanni Visentin's user avatar
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0 answers
28 views

RFID antenna and LoRa module/flex antenna on the same PCB

I need to place LoRa module on the PCB I designed. There is already an RFID antenna on this PCB that I designed before, and it is not possible to change its location. Is the distance between LoRa ...
harmonica's user avatar
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Operational Amplifier Driving Circuit

I am trying to do this circuit like screenshot. Why we need this highlighted part? What is the purpose? Is it filter or driving part of the amplifier? Please explain. image is taken from LT1994 ...
bb0667's user avatar
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MFRC522 RFID module with flat cable as antenna

I saw a commercial product that used a "hacked" MFRC522 RFID module PCB (those cheap RC522 modules that you can find everywhere) and a long flat cable as antenna (like this) to obtain a long ...
Dimitri Petrucci's user avatar
1 vote
1 answer
145 views

Calculate RF shielding property of aluminum sheet

I want to quantify the radio-frequency shielding properties of a sheet of aluminum. I have an RFID antenna shooting at 865 MHz and I want to shield the antenna so that I don't pick up tags behind the ...
nndei's user avatar
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1 vote
1 answer
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Android tablet, RFID reader module + Charging with one USBC port [closed]

I came here to ask you for some advice, comments or a completely different approach to my project. I have an Android tablet with a USB-C port and I would like to connect to the port RFID reader module ...
Thomas Frost's user avatar
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1 answer
40 views

RFID allow write operation only if authenticated

According to this page at rfidjournal.com: Microchips in RFID tags can be read-write, read-only or “write once, read many” (WORM). With read-write chips, you can add information to the tag or write ...
Muhammad Ikhwan Perwira's user avatar
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0 answers
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Device Design using RFID, Transistors, and a Wet Sensor Element

I'm seeking advice on a circuit design that I hope will function as follows: I am attempting to design an RFID device in which the Q-factor is dictated by a 'sensor-resistor' element which responds to ...
schmemical_engineer's user avatar
0 votes
1 answer
75 views

Find my keys via RFID

I'm not an electrical engineer (software guy) so I really don't know if this is possible, but I thought I'd ask some smart people before I give up. I've been missing the keys to my 2021 Toyota Sienna ...
NateW's user avatar
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PN532 RFID Reader IC taking up 4mA even when there is no power applied

I have designed a custom PCB for one of my side projects. PN532 is interfaced with ESP32 over i2c. Goal is to have the system consume current in uAmps range when in deep sleep. I put ESP32 in deep ...
Hamza's user avatar
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2 answers
141 views

How could I detect my cat from 1 meter away?

I am building an automated pet feeding system. One of the functions has to be that the system detects that the pet is near. I was thinking of using an RC-522 RFID, but the range on that is 10 cm ...
Matas's user avatar
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1 answer
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Role of secondary antenna for a UHF RFID tag

I am trying to understand the role of a secondary antenna that I have seen in some UHF RFID tags. I believe it's to increase the read range of the tag. The module seems to have an internal antenna ...
Zaffresky's user avatar
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63 views

Design grid of RFID readers with possible stacked tags

I want to get a grid of RFID readers in rather close proximity (cells should be around 45mm x 45mm -- could increase a bit if necessary). I also want to be able to detect up to at least 3 stacked tags ...
alex10791's user avatar
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1 vote
1 answer
187 views

How do I detect a Faraday bag? [closed]

How do I detect a Faraday bag coming into or leaving my store? The intention of detecting Faraday bags is to be aware of customers who have the ability to walk out of the store with an RFID-tagged ...
Michael's user avatar
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1 answer
299 views

RFID tag sensitivity values

The datasheets of the passive UHF RFID tags mentions the read and write sensitivity values in dBm. I see that the reader transmit power is usually mentioned in watts and dBm values can be converted to ...
Zaffresky's user avatar
1 vote
1 answer
193 views

RFID-based access control system

I want to make a RFID-based access control system with an ESP32 and the Arduino IDE. I found code from electronoobs and a video; it looks nice. I have tested it, and it works with the RC552. When ...
mehmet's user avatar
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1 answer
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RFID Antenna Simulation using MATLAB

I have designed a PCB with RFID antenna and I want to simulate this antenna. I know I need to use PCB Antenna Design APP in MATLAB for this. My MATLAB version is 2017b, this version only has Antenna ...
harmonica's user avatar
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2 votes
1 answer
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RFID tag performance - single frequency vs band

I am trying to understand the RFID frequency bands but have some confusion. RFID tags operate on two different frequency bands 865 to 868 MHz (European) & 902-928 MHz. Are the RFID readers ...
Zaffresky's user avatar
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1 answer
264 views

Connecting LCD I2C and RFID tag to esp 32 devkit

I want to connect LCD I2C and RFID card reader to esp32 devkit. My problem is they both have SDA pin and on esp I only see one, so how can I work on that?
Casey Ntsako's user avatar
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0 answers
159 views

Arduino isn't seeing PN532 chip

I am having an issue with the PN532 reader: I would like to use the module with an Arduino Uno, and read 13.56 MHz tags. I choose the UART connection, and soldered pin, as shown here: *EDIT, the ...
BruceWawe's user avatar
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0 answers
60 views

Powering a 1mA - 100mV amplifier with the output of an MCU without directly supplying 1mA

I'm trying to design a super low power consumption tag for RFID applications. The idea is to power all the circuitry with the I/O of the microcontroller. I am assessing two different low power ...
marclazaromarti's user avatar
1 vote
2 answers
125 views

3D RFID LF coil antenna - resonance

I'm designing a 3D 125 kHz RFID only-receiver (you can think about it as a field detector - the tag will not respond with classic field load modulation), which will have three separate coils in XYZ ...
Felix's user avatar
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0 answers
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How to decide RFID tag antenna inductance?

I know how to calculate the antenna inductance of a given RFID tag antenna but how do I decide what value of antenna inductance is needed for the design?
Arun Kumar Thawait's user avatar
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0 answers
85 views

Limits to I2C switching multiple RFID/NFC readers with Raspberry Pi and I2C switch

I am trying to set up an assembly line scenario where an item with and RFID tag is slid across an assembly line to different stations on a table. In the image below you can see ID tags A and B as they ...
nk13's user avatar
  • 65
1 vote
0 answers
104 views

1 vs. 2 balun(s) on extension cable

I am quite new to SDR and RF learning and experimenting. I am trying to build an extension cable to relay an RFID signal (125kHz) to various distances (2,5,10m). I am using 2 identical antennas at ...
gcaglion's user avatar
0 votes
0 answers
220 views

125 kHz Arduino RDM6300 read issue

I've tried to read a 125 kHz signal with an Arduino using an RDM6300 module, but it didn't work. I tried to catch the signal with Audacity. Please find attached photo with the signal. How can I catch ...
Zilvinas's user avatar
1 vote
1 answer
82 views

RFID project using STM32F446 Nucleo board, I need to feed my board with 5 V using a powerbank, is that possible?

I'm working on an RFID project using an STM32F446 Nucleo board. I need to feed my board with 5 V using a powerbank, is that possible?
electronic guy's user avatar
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0 answers
46 views

Receiver antenna design for reading PIT tags implanted in snakes and reptiles

I am talking to a local conservation outfit trying to replace active implantable radio tags with passive PIT tags (I do not know who the manufacturer is). These active tags are really tiny glass ...
user3418620's user avatar
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0 votes
1 answer
47 views

NodeMCU RF522 connection not working

I have a NodeMCU which is connected to a RF522 sensor and a LCD display. I did the connection as follows D4-SDA D5-SCK D7-MOSI D6-MISO GND-GND RST-D3 3V-3.3V LCD-I2C is connected nodeMCU as: GND-GND ...
OISHIK SENGUPTA's user avatar
3 votes
1 answer
1k views

Why does my phone's RFID UID change each time I scan it on a RFID scanning system?

I am currently playing around with RFID on my Arduino UNO using RC522 module. I have followed a code tutorial from this website https://arduinogetstarted.com/tutorials/arduino-rfid-nfc and am able to ...
scelectron's user avatar
0 votes
0 answers
1k views

mfrc522 Arduino library -> RFID ERROR: PCD_Authenticate() failed: Timeout in communication

I'm trying to do a project using RFID tags to store information to be retrieved later with another device. Kind of a storage memory. I've bougth several tags which I can write and read with several ...
Angel's user avatar
  • 1
0 votes
0 answers
262 views

Multiple antenna single rfid

I am using 134.2 kHz RFID reader module. My module has VCC pin (5V-12V), GND , TX(don't have RX pin, Module has one way communication) and reset pin. I need to use at least 4 RFID reader for my ...
mrneedshelpalot's user avatar
6 votes
3 answers
3k views

RF coils in UK roads tarmac

I'm not sure if this the right place to ask, but I think it's still related here. Increasingly, I've been noticing more and more rectangular cut-throughs in the tarmac of UK roads. Usually, they are ...
zmechanic's user avatar
  • 304
0 votes
0 answers
241 views

Antenna inductance calculation (RFID applications, inductive coupling)

Inductance of various antenna coils of different shapes can be estimated. Some examples are: A circular coil with single turn. N turn multilayer circular coil. Spiral coil. N turn squae loop coil. ...
Ethz's user avatar
  • 1
-1 votes
1 answer
311 views

How can I read an RFID tag at the back of a phone FROM THE FRONT?

I'm discovering RFID applications and I would like to be able to read an RFID card I strapped to the back of my phone (the most convenient location for me) by just putting the phone face down on the ...
user42875's user avatar
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0 votes
1 answer
70 views

Multiple Tags with RFID then play media from RPi

I was wondering if it is at all possible for an RFID reader to read an NFC tag, then ignore that tag, while still being available for other tags which are placed in sequence? The project is a board ...
Jim's user avatar
  • 1
0 votes
1 answer
411 views

How does the resonant capacitor work in an RFID antenna?

I am trying to design a custom antenna for an RFID circuit I am building. I want to make a ~20 cm circular antenna to read a tag that passes through. I still can't have success. Reading this http://...
academo's user avatar
1 vote
1 answer
938 views

125 kHz RFID antenna and read range relation

I have designed 125 kHz RFID reader circuit with which I can read regular card type tags around 4-5 cm and key tag type around 2 cm range. You can see my current circuit and antenna information from ...
U.Sim's user avatar
  • 69
0 votes
0 answers
61 views

What would be the best small signal model to the following LF RFID circuit?

I'm trying to analyse a LF RFID circuit's antenna of a TMS3705 base station using simulation. I want to estimate the frequency response and the Q factor. The intention is to do it for two different ...
Daniel's user avatar
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