{"product_id":"hc-05-hc-06-bluetooth-serial-module-master-slave-6pin-4pin-uart-arduino","title":"HC-05 \/ HC-06 Bluetooth Serial Module | Master-Slave | 6-Pin \/ 4-Pin | Wireless UART Pass-Through | Arduino","description":"\u003ch2\u003eHC-05 \/ HC-06 Bluetooth Serial Module — Master-Slave | 6-Pin \/ 4-Pin | Wireless UART Pass-Through | Arduino\u003c\/h2\u003e\n\n\u003cp\u003eThe \u003cstrong\u003eHC-05 and HC-06\u003c\/strong\u003e are the most widely used Bluetooth serial modules in the Arduino and embedded systems community — providing a simple, transparent UART-to-Bluetooth bridge that makes any serial device wireless without changing the application code. Data sent to the module’s UART TX\/RX pins is transmitted wirelessly via Bluetooth 2.0 SPP (Serial Port Profile) to a paired device — a smartphone, PC, or another HC-05\/HC-06 module. The key difference between the two: the HC-05 supports both master and slave modes (can initiate connections), while the HC-06 is slave-only (waits for connections). Both are configured via AT commands and operate at 5V with a -40°C to +85°C operating range.\u003c\/p\u003e\n\n\u003ch3\u003eSpecifications\u003c\/h3\u003e\n\u003ctable\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eBluetooth Version\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eBluetooth 2.0 + EDR (SPP)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eSupply Voltage\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e5V DC\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eOperating Temperature\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e-40°C to +85°C\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003ePackage\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eDIP (through-hole, breadboard compatible)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eInterface\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eUART (TX, RX, VCC, GND)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eDefault Baud Rate\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e9600 bps (configurable via AT commands)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003ePairing PIN\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e1234 (default, configurable)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eRange\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e~10 metres (Class 2)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eApplication\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eWireless serial communication, Arduino wireless control\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eOrigin\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eMainland China\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eHC-05 vs. HC-06 — Which to Choose\u003c\/h3\u003e\n\u003ctable\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n\u003cth\u003eFeature\u003c\/th\u003e\n\u003cth\u003eHC-05\u003c\/th\u003e\n\u003cth\u003eHC-06\u003c\/th\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003eMode\u003c\/td\u003e\n\u003ctd\u003eMaster + Slave (configurable)\u003c\/td\u003e\n\u003ctd\u003eSlave only\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003eCan initiate connection\u003c\/td\u003e\n\u003ctd\u003eYes (master mode)\u003c\/td\u003e\n\u003ctd\u003eNo\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003ePins\u003c\/td\u003e\n\u003ctd\u003e6-pin (includes EN\/KEY and STATE)\u003c\/td\u003e\n\u003ctd\u003e4-pin (TX, RX, VCC, GND)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003eAT command mode\u003c\/td\u003e\n\u003ctd\u003eVia KEY pin (hold HIGH at power-on)\u003c\/td\u003e\n\u003ctd\u003eVia baud rate change\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003eModule-to-module\u003c\/td\u003e\n\u003ctd\u003eYes (one master, one slave)\u003c\/td\u003e\n\u003ctd\u003eNo (slave only)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003eBest for\u003c\/td\u003e\n\u003ctd\u003eModule-to-module wireless, master control\u003c\/td\u003e\n\u003ctd\u003eSmartphone\/PC to Arduino wireless\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003ePin Description (HC-05, 6-Pin)\u003c\/h3\u003e\n\u003ctable\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n\u003cth\u003ePin\u003c\/th\u003e\n\u003cth\u003eFunction\u003c\/th\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003eVCC\u003c\/td\u003e\n\u003ctd\u003ePower supply (5V)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003eGND\u003c\/td\u003e\n\u003ctd\u003eGround\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003eTXD\u003c\/td\u003e\n\u003ctd\u003eUART transmit (connect to Arduino RX)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003eRXD\u003c\/td\u003e\n\u003ctd\u003eUART receive (connect to Arduino TX)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003eEN \/ KEY\u003c\/td\u003e\n\u003ctd\u003eAT command mode enable (hold HIGH at power-on)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003eSTATE\u003c\/td\u003e\n\u003ctd\u003eConnection status indicator (HIGH = connected)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eKey Features\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e✅ \u003cstrong\u003eTransparent UART bridge\u003c\/strong\u003e — no protocol changes needed, data passes through as-is\u003c\/li\u003e\n  \u003cli\u003e✅ \u003cstrong\u003eHC-05 master+slave\u003c\/strong\u003e — can initiate connections to other Bluetooth devices (module-to-module wireless)\u003c\/li\u003e\n  \u003cli\u003e✅ \u003cstrong\u003eHC-06 slave\u003c\/strong\u003e — simple slave-only operation for smartphone and PC wireless control\u003c\/li\u003e\n  \u003cli\u003e✅ \u003cstrong\u003eAT command configuration\u003c\/strong\u003e — configure baud rate, device name, PIN, and mode via AT commands\u003c\/li\u003e\n  \u003cli\u003e✅ \u003cstrong\u003e5V supply\u003c\/strong\u003e — compatible with Arduino 5V systems (use voltage divider on RX for 3.3V systems)\u003c\/li\u003e\n  \u003cli\u003e✅ \u003cstrong\u003e-40°C to +85°C\u003c\/strong\u003e — suitable for industrial and outdoor applications\u003c\/li\u003e\n  \u003cli\u003e✅ \u003cstrong\u003eDIP package\u003c\/strong\u003e — breadboard and Dupont cable compatible\u003c\/li\u003e\n  \u003cli\u003e✅ \u003cstrong\u003e~10 metre range\u003c\/strong\u003e — adequate for most indoor wireless control applications\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eCommon Applications\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eArduino wireless control via smartphone app (MIT App Inventor, Bluetooth Terminal)\u003c\/li\u003e\n  \u003cli\u003eWireless serial monitor for remote debugging\u003c\/li\u003e\n  \u003cli\u003eRobot wireless control (HC-05 master on controller, HC-05 slave on robot)\u003c\/li\u003e\n  \u003cli\u003eWireless sensor data transmission to PC\u003c\/li\u003e\n  \u003cli\u003eBluetooth-controlled relay and switch\u003c\/li\u003e\n  \u003cli\u003eWireless data logger\u003c\/li\u003e\n  \u003cli\u003eRC car and drone Bluetooth control\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eArduino Wiring\u003c\/h3\u003e\n\u003col\u003e\n  \u003cli\u003eConnect HC-05\/HC-06 VCC to Arduino 5V, GND to GND.\u003c\/li\u003e\n  \u003cli\u003eConnect HC-05\/HC-06 TXD to Arduino RX (pin 0 or SoftwareSerial RX pin).\u003c\/li\u003e\n  \u003cli\u003eConnect HC-05\/HC-06 RXD to Arduino TX via a voltage divider (1kΩ + 2kΩ) to reduce 5V TX to ~3.3V for the module RX.\u003c\/li\u003e\n  \u003cli\u003ePair the module with your smartphone (PIN: 1234 default).\u003c\/li\u003e\n  \u003cli\u003eUse a Bluetooth terminal app to send and receive serial data.\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eQ: Can I use HC-05\/HC-06 with an ESP32 or Raspberry Pi?\u003c\/strong\u003e\u003cbr\u003eA: Yes, but note that ESP32 and Raspberry Pi use 3.3V logic. The HC-05\/HC-06 RX pin is 5V tolerant, but use a voltage divider or level shifter on the TX line from the module to the 3.3V device to be safe.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eQ: What is the difference between “original” and “compatible” variants?\u003c\/strong\u003e\u003cbr\u003eA: The “original” variant uses the genuine HC-05\/HC-06 module with the original firmware. The “compatible” variant uses a compatible module with equivalent functionality at a lower price point.\u003c\/p\u003e\n\n\u003ch3\u003ePackage Contents\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e1× HC-05 or HC-06 Bluetooth Serial Module (variant as selected)\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Keszoox","offers":[{"title":"HC-05 original","offer_id":46991410004203,"sku":"14:350852#HC-05 original","price":16.16,"currency_code":"USD","in_stock":true},{"title":"HC-05 compatible","offer_id":46991410036971,"sku":"14:1202#HC-05 compatible","price":7.0,"currency_code":"USD","in_stock":true},{"title":"HC-06 original","offer_id":46991410069739,"sku":"14:4044226#HC-06 original","price":16.16,"currency_code":"USD","in_stock":true},{"title":"HC-06 compatible","offer_id":46991410102507,"sku":"14:351074#HC-06 compatible","price":7.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0677\/1005\/8731\/files\/hc05-hc06-bluetooth-serial-module-master-slave-arduino.webp?v=1761968755","url":"https:\/\/keszoox.com\/products\/hc-05-hc-06-bluetooth-serial-module-master-slave-6pin-4pin-uart-arduino","provider":"Keszoox","version":"1.0","type":"link"}