The HC-12 is a configurable wireless serial bridge: connect a module to each endpoint, configure both compatibly, and exchange UART data without programming the RF circuitry yourself. Its published range figures are approximate, not guarantees; the V2.6 manual says about 500 m under its stated default setting.
What the HC-12 does—and what it does not
The HC-12 carries data between a device’s UART serial interface and a radio link. Its onboard controller handles the radio side, so a basic microcontroller project can communicate through ordinary serial data rather than directly controlling an RF transceiver. The V2.6 manual describes it as a “multi channel embedded wireless data transmission module.” HC-12 V2.6 User Manual
A working connection requires two modules—one at each endpoint. The HC-12 is best treated as a transparent serial bridge, not a complete addressed networking system. The technical guide describes no native addressing or packet framing; applications that need multiple nodes, message boundaries, sender identification, or collision handling must implement those behaviors themselves. HC-12 technical guide
Published specifications and realistic range expectations
The V2.6 manual, dated July 11, 2018, lists the following manufacturer specifications. They are documentation figures, not independent measurements of a particular installation.
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- HC-12 Power Supply Voltage: 3.2V~5.5V. (If the module is to be in the transmitting state for a long time, it is recommended to connect a 1N4007 diode in series when the power supply voltage exceeds 4.5V to avoid the built-in LDO heating of the module).
- Default Communication Distance(open field test): about 600m (the communication distance can be adjusted up to 1000m, the air baud rate is 5000bps).
- Default Idle Current: 16 mA (module operating current is different in different operating modes).
- Operating Frequency Range(433.4-473.0MHz, up to 100 communication channels), maximum 100mW transmit power (settable).
- Default Factory Setting: working mode FU3, baud rate 9600bps, communication channel CH001 (433.4M).
| Specification | HC-12 V2.6 manual |
|---|---|
| Operating frequency range | 433.4–473.0 MHz |
| Transmit power | Up to 20 dBm |
| Supply voltage | 3.2–5.5 V |
| Channels | 100 channels at 400 kHz spacing |
| Communication distance | About 500 m under the manual’s stated default setting |
The V2.4 manual copy presents distance inconsistently: it gives an approximately 1,000 m headline, while also describing roughly 500 m at an air data rate of 5,000 bps. Neither figure should be treated as a promised field range. Actual distance depends on the installation and operating conditions; verify the link in the environment where the project will be used. HC-12 V2.4 manual copy
Frequency and power settings are also subject to local rules. Permitted channels, transmit power, and duty cycle vary by jurisdiction, so check the requirements that apply where the device will operate rather than assuming every 433 MHz setting is allowed.
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- ★Module Size: 27.8mm*14.4mm*4mm; Power Supply Voltage: 3.2V~5.5V. (If the module is to be in the transmitting state for a long time, it is recommended to connect a 1N4007 diode in series when the power supply voltage exceeds 4.5V to avoid the built-in LDO heating of the module).
- ★Default Idle Current: 16 mA (module operating current is different in different operating modes).
- ★Operating Frequency Range(433.4-473.0MHz, up to 100 communication channels), maximum 100mW transmit power (settable).
- ★Default Communication Distance(open field test): about 600m (the communication distance can be adjusted up to 1000m, the air baud rate is 5000bps).
- ★Default Factory Setting: working mode FU3, baud rate 9600bps, communication channel CH001 (433.4M).
Plan the serial and radio configuration
The module’s serial interface is used for ordinary data and configuration. Its manuals describe selectable FU modes and AT-command setup. Mode choice involves tradeoffs such as power use, throughput, and range; consult the manual for the specific module revision instead of assuming settings or behavior are identical across revisions. Both endpoints must use compatible settings.
Before connecting the modules, record the configuration for each endpoint. At minimum, document the FU mode, serial baud rate, and radio channel. If the project changes any other radio or serial settings, record those too. This makes it easier to diagnose a silent or unreliable link and reproduce a working setup. HC-12 V2.6 User Manual
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- HC-12 Power Supply Voltage: 3.2V~5.5V. (If the module is to be in the transmitting state for a long time, it is recommended to connect a 1N4007 diode in series when the power supply voltage exceeds 4.5V to avoid the built-in LDO heating of the module).
- Default Communication Distance(open field test): about 600m (the communication distance can be adjusted up to 1000m, the air baud rate is 5000bps).
- Default Idle Current: 16 mA (module operating current is different in different operating modes).
- Operating Frequency Range(433.4-473.0MHz, up to 100 communication channels), maximum 100mW transmit power (settable).
- Default Factory Setting: working mode FU3, baud rate 9600bps, communication channel CH001 (433.4M).
Connect an HC-12 to a microcontroller
Use the actual module and development-board pinouts; there is no universal Arduino pin mapping established for every board and module revision. Confirm the UART voltage requirements and ensure the chosen connections are compatible.
- Provide module power. Use a supply within the manual’s specified 3.2–5.5 V range, and make sure the design can support the module’s transmit-current demand. The V2.4 manual copy reports a maximum transmit-state current of 100 mA; treat that as a figure from that manual version, not a guarantee for every board or revision.
- Connect a common ground. Join the microcontroller ground and HC-12 ground so their serial signals share a reference.
- Connect the UART. Wire the microcontroller’s transmit and receive signals to the HC-12’s corresponding serial receive and transmit pins, following the pin labels and voltage requirements for the exact hardware.
- Configure both modules. Set compatible FU modes, serial baud rates, and channels using the documented AT-command procedure for the applicable revision.
- Test a simple exchange. Send a recognizable serial message from one endpoint and check that the other receives it. Then test the intended message size, operating distance, and environment; a basic successful exchange does not establish robust delivery at all ranges.
The V2.4 manual copy also reports average idle current of 3.6 mA in FU1, 80 μA in FU2, 16 mA in FU3, and 16 mA in FU4. These values are specific to that manual copy and should not be assumed universal across all HC-12 boards. HC-12 V2.4 manual copy
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- HC-12 wireless module 1000M 433m wireless transceiver transmission and communication data transmission module serial port
Design messages for a transparent serial link
Because the link does not provide native addressing or packet framing, decide how the receiving application will recognize message boundaries. For a two-device project, that may mean choosing a delimiter or fixed-length message format. For a multi-node design, include message identifiers and implement whatever collision-management behavior the application requires. Do not assume the module itself provides addressed delivery or robust delivery guarantees. HC-12 technical guide
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Choose the module, antenna, and settings carefully
Module revisions and retail bundles can differ. Before ordering or assembling a project, check the exact board’s pinout, antenna connector, whether an antenna is included, and the supply capability required by the design. Confirm that an antenna matches the module’s frequency and connector rather than relying on a generic product photo or bundle description. HC-12 technical guide HC-12 product listing
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- Power supply voltage : 3.3V
- Default communication distance: about 1000 meters
- Default idle current: 16 ma
- Module size: 27.8mm*14.4mm*4mm
Compare configurations according to the project’s constraints, not a presumed best mode: FU modes balance power use, throughput, and range; channel, serial baud, and power settings determine the configuration to reproduce at both ends. The available documentation does not provide independent head-to-head performance measurements, so it cannot establish which mode or retail revision performs best in a particular installation.
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