Spark Logic

HC-05 Classic Bluetooth serial module connection guide

HC-05 Classic Bluetooth serial module HC-05 bare module wiring guide with power, signal assignments, and bench checks.

HC-05 bare module

34 contacts Current package

Guangzhou HC / Wavesen · 34 castellated contacts and an integrated antenna.

Read the HC-05 AT response

Required

With power off, wire the UART and connect PIO11 high. Apply 3.3 V and set the terminal to 38400 bit/s, 8 data bits, no parity and one stop bit.

  • 3.3 V supply
    • VCC (12)
    • Regulated 3.3 V
    • C1.1
    • PIO11 (34)
    • R1.1
  • Ground
    • GND (13)
    • GND (21)
    • GND (22)
    • Supply return
    • Host ground
    • C1.2
  • Host to module
    • UART_RX (2)
    • Host UART TX
    • R1.2
  • Module to host
    • UART_TX (1)
    • Host UART RX
C1 100 nF between 3.3 V supply and Ground3.3 V supplyC1 100 nFGround
R1 10 kΩ between 3.3 V supply and Host to module3.3 V supplyR1 10 kΩHost to module

Bench checks

  • Send uppercase AT followed by CR and LF. Check that the reply contains OK.
  • For normal serial operation, power off and set PIO11 low before restarting. Normal UART speed follows the saved configuration.

Guangzhou HC HC-05 user instructional manual, hardware connection and command-mode instructions.

HC-05 bare module wiring map

Select a contact to inspect it.

HC-05 bare module
Component-side view with the antenna at the top. Pad 1 is at upper left. The numbering passes down the left side, across the bottom and up the right side. Scroll the map to reach all contacts.
Selected pin details

21 · GND

Return · Ground

Common return. Connect every GND contact.

Guangzhou HC HC-05 Module Data Sheet, § 3

Electrical limits · Pin in the reference

Models and documents

The 34-pad Wavesen HC-05 follows the 2011 module drawing. Breakout headers, carrier buttons and firmware command dialects are specific to their respective boards.

Wavesen HC-05
34-pad BC04 module documented in April 2011.