# Radio serial communication module, 433MHz, HC-12, SI4438, 1km

> HC-12 radio transceiver module with SI4438 chip, UART/TTL interface, for bidirectional wireless communication at 433MHz. Transmission range up to 1km in open field, adjustable output power up to 20dBm, maximum speed 115200bps, configurable via AT commands. Operating voltage 3.2-5.5VDC, metal helical antenna included, dimensions 29 x 13mm. Not compatible with HC-11 or HC-06 modules.

- Page: https://sigmanortec.ro/en/radio-serial-communication-module-433mhz-hc-12-si4438-1km
- Price: 30.50 RON
- Availability: In stock; 1-2 zile
- Reference: 9587 · EAN: 5946696352601
- Category: Mechatronics and IoT > Sensors and Modules > RF and Radio Modules
- Package (shipping data): 0.002 kg
- Updated: 2026-09-23
- Shop: [Sigmanortec.ro](https://sigmanortec.ro/en/llms.txt)
- Prices: RON, VAT included; prices and stock as of 2026-10-22 04:32 (Europe/Bucharest)

## Description

Radio transceiver module with UART TTL interface for wireless communication at 433MHz, ideal for remote serial links between microcontrollers, sensors or industrial equipment. Offers bidirectional communication up to 1km in open field, adjustable transmission power up to 20dBm, speed up to 115200bps and quick configuration via AT commands, with antenna included.
The HC12 module is a wireless radio transceiver module with a serial port. It uses SI4438 technology and is able to transmit and receive radio signals in the 433MHz frequency band. Due to the long transmission distance, up to 1000m, this module is ideal for use in applications that require remote communication, such as monitoring systems, security systems, drones and others.
Specifications:
Working voltage: 3.2V - 5.5VDC ( recommended below 4.5V . If the voltage exceeds 4.5V, a 1N4007 diode is recommended to prevent overheating)
Current consumption during transmission: 100mA at 20dBm
Current consumption during reception: 22mA
Standby consumption: 16mA
Communication distance: 600 meters in the open field with the default address range, up to 1000 meters with a baud rate of 5000bps
Transmission distance: up to 1000m in environments without obstacles
Output power: up to 20dBm (adjustable)
Maximum transmission power: 100mW, adjustable
Working frequency: 433.4 - 473.0MHz, up to 100 communication channels
Maximum transmission speed: 115200bps
Communication protocol: UART / TTL
OTA Updates: Yes, supported
Communication: Bilateral, in both directions, both on transmission and on reception
Default settings: FU3, baud rate 9600bps, communication channel CH001 (433.4MHz)
Antenna: Metal helical, included
Dimensions mm: 29 x 13mm
Notes:
This module is not compatible with other products that use HC-11 or HC-06 technology. Also, in order to obtain optimal transmission performance, an external antenna better than the one included in the package is required.
AT commands:
If you use an Arduino Uno, then connect the Rx pin of the module to pin 3 of the Arduino Uno (supposed to be the same for Arduino Mega), and the Tx pin to pin 2 of the Arduino . Also, connect the SET pin of the module to the GND of the Arduino and ground to ground, but do not connect Vcc yet. You must first start Arduino and then connect Vcc.
Afterwards, in Arduino IDE, compile the following code:
\#it includes
SoftwareSerial mySerial(2, 3); // TX, RX
void setup() {
Serial.begin(9600);
Serial.println("Enter AT commands:");
mySerial.begin(9600);
}
void loop() {
if (mySerial.available())
Serial.write(mySerial.read());
if (Serial.available())
mySerial.write(Serial.read());
}
Open the serial monitor and you can enter AT commands.
Example AT commands (x is variable):
AT -> returns OK
AT +Bxxxx -> Set the desired baud rate (example AT +B9600) -> return OK +Bxxxx
Serial port baud rate | 1200 | 2400 | 4800 | 9600 | 19200 | 38400 | 57600 | 115200
Baud Rate "Over the Air" | 5000 | 15000 | 58000 | 236000
Receiver sensitivity depending on Baud Rate "In Air" | -117 dBm | -112 dBm | -107 dBm | -100dBm
AT +Cxxx -> Change the channel, between 001 and 127 (example AT +C001) -> Note: Because the sensitivity of the HC-12 wireless receiver module is relatively high, the baud rate must be higher than 58000 bps, which requires the use of an adjacent channel. If the baud rate is not higher than 58000 bps, and the communication is carried out over short distances (10 meters), five adjacent channels must be used alternately.
AT +FUx -> Change between serial mode FU1, FU2 and FU3 (default FU3) -> the two modules used to communicate must be set in the same serial communication method.
Mode | FU1 | FU2 | FU3 | FU4
Standby current | 3.6 mA | 80uA | 16mA | 16mA
delay Transmission (delay) | 15-25 ms | 500 ms | 4-80ms | 1000 ms
Maximum operating range in meters | 100 m | 100 m
600m (9600bps)
1000m (2400bps)
1800m (1200bps)
AT +Px -> Set the transmission power of the module as follows (default 8):
x value
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8
Transmission power in dBm
-1 | 2 | 5 | 8 | 11 | 14 | 17
20
Transmission power in mW
0.8 | 1.6 | 3.2 | 6.3 | 12 | 25 | 50
100
Pins:
VDC: 5V
TXD: RX Arduino
RXD: TX Arduino
GND: Arduino GND
SET: Connected to GND Arduino only to enter AT Mode . In order to work then the SET pin must be disconnected from GND.
Arduino example:
In Arduino IDE, compile the following code in both the receiver and transmitter boards:
\#it includes
SoftwareSerial HC12(10, 11); // HC-12 TX Pin, HC-12 RX Pin
void setup() {
Serial.begin(9600); // Serial port to computer
HC12.begin(9600); // Serial port to HC12
}
void loop() {
while (HC12.available()) { // If HC-12 has data
Serial.write(HC12.read()); // Send the data to Serial monitor
}
while (Serial.available()) { // If Serial monitor has data
HC12.write(Serial.read()); // Send that data to HC-12
}
The text to be transmitted will be entered in the serial monitor. Communication is bilateral, both acting as receiver and transmitter.
Note: if the same PC is used for both the transmitter and the receiver, the transmitter will be connected and compiled first, the serial monitor will be opened on the related port, then the second Arduino will be connected with the receiver, the code will be compiled in a window the new Arduino IDE on the port related to the receiver, then the COM port dedicated to the receiver will open. In the case of using two computers, the ports are separated anyway, so this is no longer valid.