Pinout

RFID-RC522 reader (SPI) pinout

Pins

SDA (SPI SS — also I2C data in other modes)
SCK
MOSI
MISO
IRQ (unused in most sketches)
GND
RST
3.3V supply — logic is NOT 5V tolerant per the MFRC522 datasheet: use a 3.3V MCU or level shifting
Reads 13.56MHz MIFARE cards and tags

Chip	NXP MFRC522
Frequency	13.56 MHz
Supported cards	ISO/IEC 14443 A, MIFARE Classic/Ultralight
Supply voltage	3.3 V
Logic level	3.3 V (not 5 V tolerant per datasheet)
Read distance	Up to ≈ 5 cm (antenna and tag dependent)
Interface	SPI up to 10 Mbit/s (chip also supports I2C, UART)
Size	≈ 60 × 40 mm

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NRF24L01 2.4GHz radio (2×4 header)Chip: Nordic nRF24L01+; Supply voltage: 1.9–3.6 V (use 3.3 V); Logic inputs: 5 V tolerant
LoRa module (RFM95W / SX1276-family)Transceiver: Semtech SX1276 (RFM95W); Frequency: 868 / 915 MHz (RFM95W); 433 MHz on RFM96/98W; Supply voltage: 1.8–3.7 V (no onboard regulator)
GPS NEO-6M module (GY-NEO6MV2)Receiver: u-blox NEO-6M; Signal: GPS L1, 1575.42 MHz; Channels: 50
SIM800L GSM moduleNetwork: 2G only: GSM/GPRS quad-band 850/900/1800/1900 MHz; Supply voltage: 3.4–4.4 V (≈ 4.0 V ideal, not 5 V); Peak current: Up to 2 A transmit bursts
CP2102 / CH340 USB-to-serial adapter (6-pin)Chip: Silicon Labs CP2102 or WCH CH340; USB: USB 2.0 full speed (12 Mbit/s); Baud rate: CP2102: 300 bps–1 Mbps; CH340: 50 bps–2 Mbps
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