Crowtail NFC reader (PN532): specs and pinout
13.56 MHz NFC/RFID reader module built on the NXP PN532 controller, with a separate PCB antenna on a connector. I2C by default, UART by changing solder pads (Elecrow wiki). The facts below are for Elecrow's Crowtail-NFC, model CRT01015N. No document for a 2.0 revision is available, so the 3.3 V rating, 28 mm range and pin labels may not apply to a 2.0 board.
Specs
| Spec | Value | Source |
|---|---|---|
| Working voltage (module) | 3.3 V | source Specification |
| Default interface (module) | I2C (IIC); UART by moving solder pads on P1 | source Introduction; Usage, UART mode |
| Protocols (module) | ISO14443 type A and type B | source Specification |
| Maximum detection distance (module) | 28 mm, depends on antenna size | source Features |
| Antenna size / connector (module) | 18 x 28 x 0.8 mm, IPX port, 50 ohm | source Specification |
| Module dimensions | 40.0 x 20.0 x 9.8 mm (L x W x H) | source Specification |
| PN532 chip (not the module): supply (PN532 VBAT) | 2.7 V to 5.4 V | source Table 1 Quick reference data |
| PN532 chip (not the module): host interfaces | SPI, I2C, high speed serial UART | source Section 2 General description; Section 3 Features |
| PN532 chip (not the module): operating ambient temperature | -30 C to +85 C | source Table: operating ambient temperature (Tamb) |
| PN532 chip (not the module): typical read range | up to 50 mm depending on antenna | source Section 3 Features |
Power
| Value | Source | |
|---|---|---|
| Supply | 3.3 V (module working voltage) | source Specification |
Pinout
Labels read from the maker's board image on the Elecrow wiki page for Crowtail-NFC (model CRT01015N). The wiki page is not titled 2.0, so a 2.0 revision is not confirmed to match. The wiki text itself gives only VCC, GND, RX and TX; the IRQ label and the IIC connector labels come from the board image only.
| Pin | Function | Voltage | Notes | Source |
|---|---|---|---|---|
| IIC header: GND | GND | Label read from the maker board image only (not in the wiki text) | source Elecrow wiki board image (Dsg14.jpg), Interface section | |
| IIC header: VCC | VCC | Label read from the maker board image only (not in the wiki text) | source Elecrow wiki board image (Dsg14.jpg), Interface section | |
| IIC header: SDA | SDA | Label read from the maker board image only (not in the wiki text) | source Elecrow wiki board image (Dsg14.jpg), Interface section | |
| IIC header: SCL | SCL | Label read from the maker board image only (not in the wiki text) | source Elecrow wiki board image (Dsg14.jpg), Interface section | |
| UART header J2: GND | GND | source Interface (board image labels); Usage, UART mode | ||
| UART header J2: VCC | VCC | source Interface (board image labels); Usage, UART mode | ||
| UART header J2: IRQ | IRQ | Label read from the maker board image only (not in the wiki text) | source Elecrow wiki board image (Dsg14.jpg), Interface section | |
| UART header J2: RX | RX | Wiki wiring: module RX to board TX1 | source Interface (board image labels); Usage, UART mode | |
| UART header J2: TX | TX | Wiki wiring: module TX to board RX1 | source Interface (board image labels); Usage, UART mode |
Build with it
Project ideas for the Crowtail NFC reader (PN532). Each link opens Soldr with the prompt filled in; Soldr assigns the pins, checks power and shows how to wire every part.
- Card-tap attendance log over serial: The module is a 3.3 V I2C device, which matches the ESP32. Log lines go to the serial monitor. Only people who agree to carry a tagged card are logged; tell them what is stored.
- Tag-tap Wi-Fi notifier: The reader sits on the ESP32 I2C pins at 3.3 V (module rating per the wiki for the documented model); a green LED with a series resistor confirms a read and the ESP32 sends the tag ID over Wi-Fi to a service you run. A learning project, not a security product; only read tags you own or whose owners agree.
- Tap-to-show message display: Both the reader and the OLED are I2C devices that can share the ESP32's I2C bus at 3.3 V.
- Tag-selected LED colour switch: Card UIDs are matched in software and one GPIO per LED with a resistor shows which card was tapped.
Common mistakes
- Using the wrong interface setting: the module is I2C by default and UART needs the solder pads on P1 moved (source: link, Introduction; Usage, UART mode)
- Crossing UART wires: the wiki wires module RX to board TX1 and module TX to board RX1 (source: link, Usage, UART mode)
- Expecting more range than the module gives: the maker states a maximum detection distance of 28 mm with this antenna (source: link, Features)
Not covered by the official source
- The Elecrow wiki page is titled Crowtail- NFC (CRT01015N); no maker page for a 2.0 revision is available. Pin labels and 3.3 V rating may differ on a 2.0 board.
- Module current draw is not stated on the wiki, so no typical current is given. The PN532 sheet's current figures are chip-level only.
- I2C address is not stated on the wiki page.
- Cards and tags are limited to ISO14443 A/B (module); NTAG and MIFARE Classic support on this module is not confirmed by a maker table.