HC-12 433 MHz UART Radio Modules and Wireless Accessories

HC-12 serial-radio modules: read the selected variant first

Find HC-12-style sub-GHz UART wireless modules, SI4438/SI4463-marked revisions and HC-12-USB computer terminal boards. This assortment also contains shared product pages with HC-05/HC-06 Bluetooth alternatives, a connector cable and unrelated components with similar “HC” prefixes. A collection name is not a packing list: verify the selected variant before assuming it is a populated HC-12 radio. Its RF protocol is not Bluetooth, Wi-Fi or a generic 433 MHz remote-control protocol merely because a supplier listing uses those words.

What a genuine HC-12-style link provides

A selected HC-12 wireless serial board is an embedded endpoint: a host microcontroller exchanges bytes with its UART interface while the board's MCU and RF section implement a configured radio link. Two compatible endpoints require matching channels, air-mode and serial configuration. Transparent UART transfer simplifies an application design but does not imply universal interoperability with other 433 MHz devices. Several source descriptions explicitly note that HC-11 and HC-12 are not matched communications partners. Check the radio silicon, firmware and revision of both endpoints when adding to an existing installation. A single-module variant normally supplies only one end of the link.

Multiple HC-12 descriptions identify board supply around 3.2–5.5 V and an operating-band configuration in the vicinity of 433.4–473 MHz; newer V4.0 SI4438 listings mention a wider upper limit around 483.8 MHz. These are statements for particular products/revisions, not an electrical or legal specification for everything in this collection. A bare RF chip's pins, a USB terminal's input and an assembled module's UART I/O have different limits. Check actual product documentation and permitted frequencies/transmit power for your jurisdiction before integrating a transmitter.

Radio, USB terminal, Bluetooth option or something else?

• Standard HC-12 boards: listings include SI4438/SI4463-named UART modules, V4.0 boards, QFN and SOP/TSSOP choices, STM8S003F3P6/F3U6-labelled variants, old/new versions, antenna-equipped modules and packs from one to 20. A variant that reads “SI4438” is not automatically SI4463; “STM8S003F3U6” identifies an MCU/board selection rather than proving radio-silicon equivalence. Match the selected board pinout and firmware before substituting it.
• V4.0 SI4438 choices: listings specifically name HC-12 V4.0 SI4438 and describe multi-channel UART, half-duplex RF and FU mode settings. Their 1 km or throughput headlines are seller scenarios tied to specified modes, not universal performance guarantees. V4.0 should not be presumed identical to an earlier QFN/SOP or SI4463 module just because it uses the HC-12 name.
• HC-12-USB computer-side boards: USB 2.0 terminal versions, including one described with a CP2104 serial bridge, are assembled USB-to-radio interfaces. Their listing quotes 4.5–5.5 V input, which is not the supply rating of a loose HC-12 radio or SI4438 chip. Check the computer driver, USB connector and paired radio revision. A USB board does not automatically include a second endpoint, and a PC terminal is not a Bluetooth dongle.
• HC-05/HC-06 and other Bluetooth-labelled variants: a shared listing offers individually selected HC-05/HC-06/HC-02/HC-04/HC-08/HC-09/HC-25/HC-42 boards, SMD-only alternatives, with-baseboard options, HC-USB-T, HC-12 and an “HC Pin Port Cable.” Only its “HC-12” selection identifies the HC-12 family; cable-only, HC-05 and HC-06 selections are different deliveries. Another page sells HC-05(6PIN) versus HC-06(4PIN) in 1/5/10-piece packs; those Bluetooth serial modules have their own pairing, role and firmware behavior. Do not present an HC-06 as an HC-12 or promise every “HC-” radio is BLE.
• JDY-31 serial Bluetooth choices: a separate page offers a “Chip” bare SMD module versus “4P” and “6P” baseboard/interface formats. It is not an HC-12 sub-GHz UART radio even when marketed as an HC-05 alternative. Bare SMD and carrier boards differ in assembly and pin access.
• Other similarly named goods: HC-49S through-hole quartz crystal resonators, HC-SR501/SR505/SR602 PIR motion-sensor variants, HF46F 5/12/24 V relays and a TPA3110D2 stereo amplifier board also appear here. Their selected variants are crystals, sensors, relays or an audio amplifier, not 433 MHz transceivers. Their voltage, load, accuracy or quantity details apply solely to their actual products.

Variants that materially change what arrives

On the SI4438-versus-SI4463 page, choices explicitly read “SI4438,” “SI4463,” “2pcs SI4438,” “2pcs SI4463,” “10pcs SI4438” and “10pcs SI4463.” The headline's first chip name cannot override that selection. Other pages offer “HC-12 F3U6” versus “HC-12 F3P6” or “STM8S003F3U6” versus “STM8S003F3P6”; follow the exact controller/board revision and pack count. “HC-12 TSSOP Module,” “HC-12 QFN Module,” “HC-12 TSSOP Red Modu” and “HC-12 Pinhead” are separate options. A header-only/pinhead selection does not establish that a populated transceiver is supplied. Review images and part descriptions for that exact option.

Old/new version variants and HC-12 V4.0 variants can differ in PCB layout, RF chip, antenna fitting, pin labelling or programmed behavior. Similar silkscreen or a vendor's generic “replace Bluetooth” label is insufficient to establish drop-in compatibility. If you need a paired set, select the right module count and validate both units together, especially when sourcing from different listings. If the shared product page includes several wireless families, confirm whether your chosen variant says HC-12 rather than HC-05, HC-06, JDY-31 or cable.

Protocol boundaries worth checking before purchase

The HC-12 is typically used as a sub-GHz serial bridge. Bluetooth HC-05/HC-06 and JDY-31 variants use a different radio and pairing mechanism; selecting them will not create an HC-12 link. “Bluetooth replacement” describes an application alternative, not Bluetooth radio compliance or phone pairing. HC-12 is also not a Wi-Fi client and cannot connect to an access point. HC-49S crystal frequency choices such as 4 MHz, 16 MHz or 32.768 MHz are oscillator components, not the module's RF channel. An HC-SR501 PIR sensor detects motion and needs an appropriate host/interface to transmit data; its presence in this collection does not turn it into a radio.

Some HC-12 supplier listings claim half-duplex over the air while others refer to full-duplex serial processing. Treat UART buffering and the RF link as different layers; verify behavior under simultaneous transmissions for your particular firmware and settings. Selecting a serial port rate is not the same as selecting an RF air rate. On an embedded design, host pins, supply domain, logic thresholds and antenna placement need to match the actual board. Design for transmit-current peaks, not only the 16 mA nominal idle figure quoted on some listings; a USB terminal, SI4438 board and a different V4.0 PCB can have different power and interface requirements.

Range, antenna and safe system design

“1000M,” “1KM” and similar headings are not a guaranteed installation range. Supplier text also describes roughly 500–600 m at some default/open-field settings and a longer result with changed air-rate/mode. The usable link depends on antenna tuning and placement, obstacles, mounting height, receiver sensitivity, RF noise, cable loss, firmware parameters and local transmit-power limits. Choose the matching antenna arrangement, then measure packet success, latency and recovery at the intended installation rather than basing a safety-critical system on a headline range figure. Do not infer certification for a selected variant from another vendor's claimed approval on a similarly named listing.

For electrical integration, distinguish module supply, USB input, UART digital level, relay coil voltage and crystal load capacitance; each belongs to a different item or node. Some supplier descriptions discuss a diode in a particular long-transmit supply scenario, but that is not a universal wiring method and should not be copied blindly. Use the selected board's verified electrical specification and a reviewed regulator/level-interface design.

Engineer's purchasing checklist

1. Identify the deliverable: HC-12 UART board, HC-12-USB terminal, Bluetooth module, cable, crystal, PIR sensor, relay or amplifier.
2. Verify selected model: SI4438/SI4463, V4.0/old/new, QFN/SOP/TSSOP, STM8S003F3P6/F3U6 board and exact quantity. A combined headline is not a combined kit.
3. Plan both endpoints: matching firmware, UART settings, radio channel, air mode and antenna. Check whether one or two boards are actually ordered.
4. Confirm electrical interface: correct whole-board input, UART levels, RF transmit current, pinout, USB bridge and host driver where appropriate.
5. Validate deployment: regional RF rules, real environment range, link failure behavior and host software before production use.

Frequently asked questions

Can an HC-12 talk to an HC-05 or HC-06? No direct compatibility is established. Those are Bluetooth-family selections, whereas HC-12 uses a distinct sub-GHz radio link.

Does the HC-12-USB listing include an embedded HC-12 partner? Not by its title alone. Check the selected package contents and obtain a compatible second endpoint if needed.

Do “SI4438” and “SI4463” mean the same radio? No. They are distinct listed choices and their hardware/firmware matching must be verified.

Are the HC-49S crystals or HC-SR501 sensors radio options? No. They are separately listed components with different functions; they remain in this collection but should be evaluated on their own specifications.

Will all HC-12 variants work at 1 km? No. A distance claim on a vendor page is not a universal guarantee; test your selected paired boards under legal settings in the intended environment.