HC-11 433MHz wireless RF serial UART Module CC1101 [Replacement to HC-12]

SKU: FA2098
Operating Frequency

433.4 – 439.0 MHz (20+ channels, 400KHz step)
Modulation

FSK (Frequency Shift Keying)
Supply Voltage

DC 3.3V – 5.5V
UART Baud Rate

1200 – 115200 bps (default: 9600 bps)
Transmit Power

-30dBm to +10dBm (8 levels, default: max)
Receiving Sensitivity

-112dBm to -95dBm
Communication Distance

1 – 40 meters (indoor, typical)
Operating Current (TX/RX)

3.5mA – 22mA (depending on mode)
Module Dimensions

27.8 × 14.4 × 4 mm

Description

The HC-11 433MHz Wireless RF Serial UART Module is a low-cost, high-performance FSK (Frequency Shift Keying) transceiver module designed for transparent wireless serial communication. Built around the popular CC1101 RF chip, this module is an excellent replacement for Bluetooth modules in many applications, offering longer range and more robust performance in challenging environments .

Unlike simple ASK (Amplitude Shift Keying) modules, the HC-11 uses FSK modulation, which provides superior noise immunity and more reliable data transmission . The module operates as a complete wireless serial link – data sent into the UART port of one module is automatically transmitted wirelessly and appears at the UART port of any other HC-11 module on the same channel. No additional RF programming or protocol handling is required by your microcontroller .

The HC-11 features a built-in MCU that handles all RF protocol processing internally. This means you simply connect the module to your microcontroller’s UART pins (TX and RX), and it functions just like a wired serial connection – but without the wires. The module supports a wide range of UART baud rates from 1200 bps to 115200 bps, making it compatible with virtually any microcontroller .

Multiple Operating Modes: The HC-11 offers four UART transparent transmission modes (FU1-FU4), allowing you to optimize for power consumption or speed:

Mode Idle Current Best For
FU1 (Default) ~3.5mA Balanced power/speed, general use
FU2 ~80µA Battery-powered, low data rate applications
FU3 ~22mA Low latency, high-speed communication
FU4 ~22mA Extended range (lower baud rate = longer range)

Configuration Flexibility: All module parameters are configurable via simple AT commands, including communication channel (001-127), UART baud rate, transmit power (8 levels), and operating mode. Settings are stored in non-volatile memory and retained after power loss .

Important Note: The HC-11 is not compatible with the HC-12 module . These two modules operate on different protocols and cannot communicate with each other. For best results, use HC-11 modules in pairs or multiples.

Whether you need to create a wireless sensor network, replace a wired serial connection between two microcontrollers, add remote control to a project, or build a wireless data logging system, the HC-11 provides a simple, reliable, and affordable wireless serial solution.

Key Features

  • 433MHz FSK Transceiver – Built on CC1101 chip, provides reliable, noise-immune wireless communication

  • Transparent Serial Communication – No RF programming needed; data in = data out wirelessly

  • Multiple Operating Modes – Four modes (FU1-FU4) with idle currents of 80µA, 3.5mA, or 22mA for power optimization

  • Wide Baud Rate Support – UART speeds from 1200 bps to 115200 bps (default 9600 bps)

  • AT Command Configuration – Set channel, baud rate, power level, and mode via simple text commands

  • Adjustable Transmit Power – 8 power levels from -30dBm to +10dBm (10mW max)

  • Wide Voltage Range – Operates from 3.3V to 5V DC, compatible with both 3.3V and 5V microcontrollers

  • Multiple Channels – 20+ selectable channels (001-127) with 400KHz step spacing

  • Compact Form Factor – 27.8mm × 14.4mm × 4mm with 2.54mm pin headers

  • Wide Temperature Range – -40°C to +85°C for industrial applications

Technical Parameters

Parameter Value
Operating Frequency 433.4 – 439.0 MHz (20+ channels, 400KHz step)
Modulation FSK (Frequency Shift Keying)
Supply Voltage DC 3.3V – 5.5V
UART Baud Rate 1200 – 115200 bps (default: 9600 bps)
Transmit Power -30dBm to +10dBm (8 levels, default: max)
Receiving Sensitivity -112dBm to -95dBm
Communication Distance 1 – 40 meters (indoor, typical)
Operating Current (TX/RX) 3.5mA – 22mA (depending on mode)
Module Dimensions 27.8 × 14.4 × 4 mm

Usage Guide

Hardware Overview

The HC-11 module features 9 pins, with the first 5 pins (1-5) typically used for standard 2.54mm header connection. The module includes both a UART interface for serial communication and a SET pin for entering command mode .

Key Components:

  • CC1101 RF Chip – Handles all wireless transmission and reception

  • Onboard MCU – Manages UART communication and AT command processing

  • ANT1 / ANT2 – Antenna connection points (spring antenna or external SMA)

Pinout Description

The HC-11 module uses the following pin configuration :

Pin Label Function Connection
1 VCC Power Supply (3.3V – 5.5V) Connect to 3.3V or 5V
2 GND Ground Connect to common ground
3 RXD / RX UART Receive (input) Connect to microcontroller TX pin
4 TXD / TX UART Transmit (output) Connect to microcontroller RX pin
5 SET Configuration Mode Enable Pull LOW to enter AT command mode
6-9 – Auxiliary/Reserved Not required for basic operation

Wiring Instructions

Basic Connection (Microcontroller to HC-11):

HC-11 Pin Arduino Pin ESP32/ESP8266 Pin
VCC 5V or 3.3V 5V or 3.3V
GND GND GND
RXD TX (Pin 1) TX (GPIO17 / TX2)
TXD RX (Pin 0) RX (GPIO16 / RX2)

Important: When connecting two HC-11 modules to communicate with each other, connect:

  • Module A RXD → Module B TXD (cross connection if both connected to same microcontroller)

Antenna Connection:

  • For optimal performance, connect a spring antenna to the ANT2 pad or use an external SMA antenna via ANT1 . A simple 17-20cm straight wire can also be used.

AT Command Configuration

Entering AT Command Mode:

There are two methods to enter AT command mode :

  1. Method 1 (Normal Operation): While the module is powered on and operating normally, pull the SET pin LOW. The module will enter command mode. Release SET to exit.

  2. Method 2 (Power-on): Pull SET pin LOW before applying power, then power on the module. After 1 second, the module enters command mode. Release SET to exit.

Important Notes for AT Commands:

  • In command mode, the UART format is fixed at 9600 bps, 8 data bits, no parity, 1 stop bit

  • Commands must be sent in uppercase

  • Each command must be terminated with \r\n (carriage return + line feed)

  • Characters within a command must be sent in quick succession

Available AT Commands :

Command Function Example Response
AT Test connection Send AT Returns OK
AT+Axxx Set module address (000-255) AT+A012 OK012
AT+Bxxxx Set UART baud rate AT+B9600 OK-B9600
AT+Cxxx Set RF channel (001-127) AT+C020 OK-C020
AT+FUx Set operating mode (1-4) AT+FU1 OK-FU1
AT+Px Set transmit power (1-8) AT+P8 OK-P8
AT+Rx Read configuration AT+RA A000
AT+V Get version AT+V HC-11_V1.9

Supported Baud Rates: 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200 bps

Channel Frequency Mapping:

  • Channel 001: 434.4 MHz

  • Channel 002: 434.8 MHz

  • …

  • Channel 020: 439.0 MHz

Transmit Power Levels :

Setting Power Setting Power
P1 -30dBm P5 0dBm
P2 -20dBm P6 +4dBm
P3 -14dBm P7 +8dBm
P4 -8dBm P8 (Default) +10dBm

Operating Modes (FU1-FU4)

Mode Idle Current Delay (1 byte) Best Application
FU1 ~3.5mA ~20ms General purpose, balanced power/speed (default)
FU2 ~80µA ~380ms Ultra-low power, battery devices, low data rate
FU3 ~22mA ~2ms Low latency, high-speed, continuous communication
FU4 ~22mA ~7ms Extended range (lower baud rate = longer range)

Arduino Example Code

Basic Serial Passthrough (Transparent Mode – No Code Required)

The HC-11 works in transparent mode by default. Simply connect the module to your Arduino’s hardware serial pins, and any data sent to Serial will be transmitted wirelessly to another HC-11 module.

cpp
// HC-11 Wireless Serial Communication
// Module connected to SoftwareSerial pins (to leave hardware Serial for debugging)

#include <SoftwareSerial.h>

SoftwareSerial hc11(10, 11);  // RX = pin 10, TX = pin 11

void setup() {
  Serial.begin(9600);    // Debug serial to PC
  hc11.begin(9600);      // HC-11 baud rate (must match module setting)
  
  Serial.println("HC-11 Wireless Serial Ready");
}

void loop() {
  // Forward data from PC Serial to HC-11 (wireless transmission)
  if (Serial.available()) {
    hc11.write(Serial.read());
  }
  
  // Forward data from HC-11 (wireless reception) to PC Serial
  if (hc11.available()) {
    Serial.write(hc11.read());
  }
}

Sending AT Commands from Arduino:

cpp
// Send AT commands to configure HC-11 module

#include <SoftwareSerial.h>

SoftwareSerial hc11(10, 11);  // RX = pin 10, TX = pin 11

void setup() {
  Serial.begin(9600);
  hc11.begin(9600);
  
  // Pull SET pin LOW to enter command mode
  pinMode(9, OUTPUT);
  digitalWrite(9, LOW);   // SET pin LOW
  
  delay(100);  // Wait for module to enter command mode
  
  // Send AT command
  hc11.println("AT");      // Test command
  delay(500);
  hc11.println("AT+V");    // Get version
  
  delay(500);
  
  // Read responses
  while (hc11.available()) {
    Serial.write(hc11.read());
  }
  
  // Exit command mode by releasing SET pin
  digitalWrite(9, HIGH);
}

void loop() {
  // Nothing here
}

Range Optimization Tips

  • Use a proper antenna – A spring antenna or 17-20cm wire significantly improves range

  • Select FU3 or FU4 mode – These modes provide better range at lower baud rates

  • Lower the baud rate – Slower data rates improve receiving sensitivity and range

  • Increase transmit power – Use AT+P8 for maximum power (+10dBm)

  • Avoid metal enclosures – Metal significantly attenuates RF signals

  • Keep modules at least 1 meter apart – Direct proximity can overload the receiver

Important Compatibility Note

HC-11 cannot communicate with HC-12 modules . These two modules use different protocols and are not interoperable. For wireless communication, all modules in your network must be HC-11 modules.

Q: What is the difference between HC-11 and HC-12?

The HC-11 and HC-12 are different modules and are not compatible with each other . Key differences:

  • HC-11: Shorter range (1-40m), lower power consumption (as low as 80µA idle), FSK modulation

  • HC-12: Longer range (up to 1000m), higher power consumption, different protocol

For most indoor and short-range applications, HC-11 is the better choice due to its lower power consumption.

Q: What is the maximum communication distance?

In typical indoor environments, the HC-11 provides reliable communication from 1 to 40 meters . Note that the modules cannot communicate reliably at distances less than 1 meter due to receiver overload . For maximum range, use FU3 or FU4 mode, lower baud rates, and proper antennas.

Q: Why can't I get into AT command mode?

Common issues and solutions :

  • Check baud rate: In command mode, the UART is fixed at 9600 bps, 8 data bits, no parity, 1 stop bit

  • Send commands quickly: All characters in a command must be sent in quick succession

  • Use proper line endings: Commands must end with \r\n (carriage return + line feed)

  • Check SET pin connection: Ensure SET pin is pulled LOW (connected to GND) to enter command mode

  • Try power-on method: Pull SET LOW before applying power, then power on

Q: Can I use this module with 3.3V microcontrollers (ESP32, Raspberry Pi, STM32)?

Yes. The HC-11 operates from 3.3V to 5.5V, making it directly compatible with both 3.3V and 5V logic systems . Connect VCC to 3.3V for lower power consumption.

Q: What is the default configuration?
Parameter Default Setting
Operating Mode FU1
UART Baud Rate 9600 bps
RF Channel 001 (434.4 MHz)
Module Address 000
Transmit Power P8 (+10dBm, maximum)
Q: What is the difference between FU1, FU2, FU3, and FU4 modes?
Mode Idle Current Best For
FU1 ~3.5mA General purpose, balanced power and speed (default)
FU2 ~80µA Battery-powered devices, low data rate
FU3 ~22mA Low latency, high-speed communication
FU4 ~22mA Extended range (lower baud rate = longer range)
Q: Can I use multiple HC-11 modules in the same area?

Yes. By setting different RF channels (AT+Cxxx command), you can have multiple independent wireless networks operating in the same area without interference. The module supports channels 001-127

Q: Can I use this module for both home and business applications?

Home users: Wireless sensor networks, remote temperature monitoring, garden irrigation control, wireless Arduino projects, replacing Bluetooth for longer range.

Business users: Industrial data collection, remote equipment monitoring, wireless sensor networks, building automation, prototype development for commercial wireless products.

Q: Does the module save settings after power loss?

Yes. All configuration settings (baud rate, channel, address, mode, power level) are stored in non-volatile memory and retained after power loss

Q: What is the difference between FSK and ASK modulation?

FSK (Frequency Shift Keying) – Used by HC-11 – changes frequency to represent data. Provides better noise immunity and more reliable communication in noisy environments .

ASK (Amplitude Shift Keying) – Used by simpler modules – changes signal strength to represent data. More susceptible to interference.

HC-11’s FSK modulation makes it more reliable than basic ASK modules.

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