1. Introduction
1.1 Brief Introduction
The EWM201-xxxAxxS series products are brand-new long-range wireless audio transmission modules launched by Chengdu EBYTE Technology. They feature flexible configuration, convenient use, and compact size. Users can configure various parameters such as transmission power, operating channel, and serial port speed according to actual needs through commands.
The EWM201-xxxAxxS series operates based on a time-division duplex (TDD) mechanism, utilizing precise time slot control and scheduling to enable half-duplex or full-duplex wireless voice communication. It also supports unicast, multicast, and broadcast intercom functions. All models support MIC input and speaker output. The module supports point-to-point, point-to-multipoint half-duplex mode, or full-duplex mode. Simply connect an external MIC, voice amplifier, speaker, antenna, and power supply to form a full-duplex intercom system.
The following four modules are standard models, with typical transmit power of 20/30 dBm, operating in the 470 MHz to 510 MHz frequency band and the 863 MHz to 928 MHz frequency band.
1.2 Features
- Domestic chip solution, utilizing domestic narrowband IoT transmission technology.
- Parameter settings via AT commands, such as switching between half-duplex and full-duplex voice communication.
- Under ideal conditions, battery-powered operation can achieve a communication range of no less than 3.5 km/5 km (tested in open environments).
- Wide data rate range, utilizing full software-based voice compression technology.
- Cost-effective and flexible application.
- Supports unicast, multicast, and broadcast intercom functions.
- Supports power output of 20dBm/30dBm.
- Industrial-grade standard design, supporting long-term use at temperatures ranging from -40°C to +85°C.
- Dual antenna options (IPEX/pinhole), facilitating user-defined secondary development and integration.
1.3 Application
- Digital intercom
- Building intercom system
- Command and control system
- Wireless alarm security system
- Wireless audio transmission
- Intelligent voice system
- Security alarm system
2. Specifications
2.1 RF Parameters
| RF parameters | Parameter (EWM201-470A20S/900A20S) | Parameter (EWM201-470A30S/900A30S) | Notice |
|---|---|---|---|
| Operating frequency band | 470MHz~510MHz | 863MHz~928MHz | Frequency band configurable |
| Airspeed | Full duplex: ≤29.8 kbps Half duplex: ≤14.9 kbps | Full duplex: ≤29.8 kbps Half duplex: ≤14.9 kbps | Full duplex: 29.8 kbps Half duplex: 14.9 kbps |
| Receiver sensitivity | Full duplex: -121dBm Half duplex: -124dBm | Full duplex: -121dBm Half duplex: -124dBm | |
| Modulation method | DPFSK | Modulation technology | |
| Radio frequency interface | IPEX/Stamp hole | Equivalent impedance approximately 50Ω | |
2.2 Electrical Parameters
| Key parameters | Performance (EWM201-470A20S/900A20S) | Performance (EWM201-470A30S/900A30S) | Notice | ||||
|---|---|---|---|---|---|---|---|
| Minimum value | Typical value | Maximum value | Minimum value | Typical value | Maximum value | ||
| Working voltage (V) | 2.7 | 3.3 | 3.6 | 2.7 | 3.7 | 5.5 | ≥3.3V/3.7V ensures output power; exceeding 3.6V/5.5V poses a risk of burnout. |
| Transmit power (dBm) | 18 | 20 | 21 | 26 | 30 | 32 | Software adjustable, error ±1dBm |
| Operating temperature (°C) | -40 | - | +85 | -40 | - | +85 | Industrial-grade design |
| Working humidity (%) | 10 | - | 90 | 10 | - | 90 | - |
| Transmit current (mA) | 91 | 94 | 95 | 365 | 680 | 910 | Instantaneous power consumption |
| Receive current (mA) | 28 | 30 | 32 | 28 | 31 | 32 | |
2.3 Audio Parameters
| Project | Specification |
|---|---|
| Encoding algorithm | OPUS |
| Voice coding rate | 10kbps |
| Audio sampling rate | 8 kHz, 16 bits |
| Audio input | 0~708mV |
| Audio Output | 14 mW/differential output 32 Ω load |
| Intercom mode | Half-duplex/full-duplex |
2.4 Hardware Parameters
| Hardware parameters | Parameter | Notice | |
|---|---|---|---|
| EWM201-470A20S/900A20S | EWM201-470A30S/900A30S | ||
| Packaging method | SMD | - | |
| Interface method | Stamp perforation (1.27 mm spacing) | Stamp perforation (2.00 mm spacing) | - |
| Communication interface | UART | Supports AT commands | |
| Serial port configuration | 921600bps 8N1 | - | |
| External dimensions | 16 * 26 mm | 26.5 * 33 mm | - |
| Product net weight | 2.0 | 4.3 | ±0.1 |
3. Mechanical Dimensions and Pin Definitions
3.1 EWM201-470A20S & EWM201-900A20S Mechanical Dimensions and Pin Definitions
| Pin Number | Pin Name | Pin Direction | Pin Function |
|---|---|---|---|
| 1 | GND | GND | Module ground wire |
| 2 | GND | GND | Module ground wire |
| 3 | GND | GND | Module ground wire |
| 4 | TXEN | Output | Send command signal, high active |
| 5 | RXEN | Output | Receive command signal, high active |
| 6 | NC | - | Empty foot (not open for use, users do not need to be concerned) |
| 7 | NC | - | Empty foot (not open for use, users do not need to be concerned) |
| 8 | NC | - | Empty foot (not open for use, users do not need to be concerned) |
| 9 | V- | Input | Volume - Button (Low Level Trigger) |
| 10 | V+ | Input | Volume + button (low level trigger) |
| 11 | PTT | Input | PTT voice intercom button (low level trigger, trigger once, switch status once) |
| 12 | VCC | 3V3 | Power supply |
| 13 | PG | GND | Module ground wire |
| 14 | NC | - | Empty foot (not open for use, users do not need to be concerned) |
| 15 | PG | GND | Module ground wire |
| 16 | PG | GND | Module ground wire |
| 17 | RST | Input | Reset signal interface |
| 18 | VDDAC | Output | MIC power pin, dedicated power output, 2.9V |
| 19 | MICIN | Input | Microphone input jack |
| 20 | AG | AGND | Analog signal ground, external MIC input connected to this ground |
| 21 | SKP_P | Output | Speaker differential signal P terminal |
| 22 | SKP_N | Output | Speaker differential signal N terminal |
| 23 | AG | AGND | Analog signal ground |
| 24 | RXD | RXD | Configure serial port RXD |
| 25 | TXD | TXD | Configure serial port TXD |
| 26 | MUTE | Input | Silent button (low level trigger) |
| 27 | UPDATE | Input | Firmware Download Pin |
| 28 | GND | GND | Module ground wire |
| 29 | ANT | RFIO | RF antenna interface |
| 30 | GND | GND | Module ground wire |
3.2 EWM201-470A30S & EWM201-900A30S Mechanical Dimensions and Pin Definitions
| Pin Number | Pin Name | Pin Direction | Pin Function |
|---|---|---|---|
| 1 | PG | GND | Module ground wire |
| 2 | ANT | RFIO | RF antenna interface |
| 3 | PG | GND | Module ground wire |
| 4 | RXEN | Output | Receive command signal, high active |
| 5 | TXEN | Output | Send command signal, high active |
| 6 | NC | - | Empty foot (not open for use, users do not need to be concerned) |
| 7 | NC | - | Empty foot (not open for use, users do not need to be concerned) |
| 8 | NC | - | Empty foot (not open for use, users do not need to be concerned) |
| 9 | PG | GND | Module ground wire |
| 10 | PTT | Input | PTT voice intercom button (low level trigger) |
| 11 | V+ | Input | Volume + button (low level trigger) |
| 12 | V- | Input | Volume - Button (Low Level Trigger) |
| 13 | PG | GND | Module ground wire |
| 14 | 5V | VCC | Module Power Interface |
| 15 | PG | GND | Module ground wire |
| 16 | PG | GND | Module ground wire |
| 17 | RESET | Input | Reset signal interface |
| 18 | PG | GND | Module ground wire |
| 19 | VDDAC | Output | MIC power pin, dedicated power output |
| 20 | AG | AGND | Analog signal ground, external MIC input is connected here |
| 21 | MICIN | Input | Microphone input jack |
| 22 | AG | AGND | Analog signal ground |
| 23 | SPK_P | Output | Speaker differential signal P terminal |
| 24 | SPK_N | Output | Speaker differential signal N terminal |
| 25 | RXD | RXD | Configure serial port RXD |
| 26 | TXD | TXD | Configure serial port TXD |
| 27 | UPDATE | Input | Firmware Download Pin |
| 28 | MUTE | Input | Silent button (low level trigger) |
| 29 | NC | - | Empty foot (not open for use, users do not need to be concerned) |
| 30 | PG | GND | Module ground wire |
4. Setup and Installation
4.1 Application Diagram
For recommended circuit diagrams, please refer to the attached document “EWM201-xxxAxxS Recommended Schematic Diagram.”
4.2 Hardware Design Considerations
- It is recommended to use a DC regulated power supply to power this module. The power supply ripple coefficient should be as low as possible, and the module must be reliably grounded.
- Please ensure the correct connection of the power supply's positive and negative terminals. Reverse connection may cause permanent damage to the module.
- Please check the power supply voltage to ensure it falls within the recommended voltage range. Exceeding the maximum voltage may cause permanent damage to the module.
- Please check the stability of the power supply; the voltage should not fluctuate significantly or frequently.
- When designing the power supply circuit for the module, it is often recommended to leave a margin of over 30% to ensure the long-term stable operation of the entire system.
- The module should be kept as far as possible from power supplies, transformers, high-frequency traces, and other components with significant electromagnetic interference.
- High-frequency digital traces, high-frequency analog traces, and power traces must avoid passing beneath the module. If it is necessary for traces to pass beneath the module, assuming the module is soldered to the Top Layer, a ground plane (fully copper-plated and properly grounded) must be applied to the Top Layer at the module contact area, and traces must be routed on the Bottom Layer near the module's digital section.
- If the module is soldered or placed on the Top Layer, routing traces arbitrarily on the Bottom Layer or other layers is also incorrect and will adversely affect the module's spurious emissions and reception sensitivity to varying degrees.
- If there are components with significant electromagnetic interference around the module, this will also greatly affect the module's performance. Depending on the intensity of the interference, it is recommended to keep the components appropriately distant from the module. If possible, appropriate isolation and shielding measures can be implemented.
- If there are traces with significant electromagnetic interference (high-frequency digital, high-frequency analog, power traces) around the module, this will also significantly affect the module's performance. Depending on the intensity of the interference, it is recommended to keep the module at an appropriate distance. If possible, appropriate isolation and shielding should be implemented.
- If the communication line uses a 5V level, a 1k-5.1k resistor must be connected in series (not recommended, as there is still a risk of damage).
- The antenna installation structure has a significant impact on module performance. Ensure the antenna is exposed and preferably oriented vertically upward.
- When the module is installed inside the chassis, use a high-quality antenna extension cable to extend the antenna outside the chassis.
- The antenna must not be installed inside a metal chassis, as this will significantly reduce transmission distance.
4.3 Test Kit Information
| Name | Functional Description |
|---|---|
| 1 Type-C | Type-C interface, taking into account both power supply and serial communication |
| 2 3.5mm headphone jack | Support MIC input and audio output |
| 3 speaker socket | Comes with speakers connected, can connect to 2W/8Ω speakers |
| 4 Onboard microphone | - |
| 5 RX indicator | When it is always on, it is in listening mode |
| 6 TX indicator | When it is always on, it is in the sending state |
| 7 Reset button | Module restart and reset |
| 8 PTT intercom button | Press once to switch the sending and receiving status |
| 9 Antenna SMA socket | Connecting the Antenna |
| 10 Voice intercom module | Pre-soldered EWM201-470A20S/ EWM201-470A30S / EWM201-900A20S, EWM201-900A30S modules |
| 11 Volume up button | Press once to increase the volume by 1, 16 levels in total |
| 12 Volume down key | Press once to reduce the volume by 1, there are 16 levels in total |
| 13 Mute button | Not yet supported |
| 14 Power consumption test interface | Current test interface |
| 15 trumpet | - |
| 16 battery holder | DC 5V, battery powered for better communication distance |
Notice:
- Choose one power supply mode, and do not use them at the same time.
- It is recommended to use DC 5V external power supply.
5. Operating Instructions
5.1 Communication Configuration
The serial port baud rate is 921,600 bps, with 8 data bits, 1 stop bit, and no parity. The parameter settings are as follows:
| Project | Parameters |
|---|---|
| baud rate | 921600 bps |
| data bit | 8 |
| stop bit | 1 |
| check digit | None |
5.2 AT Command Format
- The module supports parameter reading and writing. The default baud rate supported by the module's serial port is 921600 bps, 8N1 format.
- AT commands end with <CR><LF>. This will not be repeated in the following description. <CR>: carriage return; <LF>: line feed.
| Command format | Description | Example |
|---|---|---|
| AT+XXX | run command | AT+RST |
| AT+XXX? | query command | AT+TXP? |
| AT+XXX=? | Query command parameter range | AT+TXP=? |
| AT+XXX=YYYY | Setup instructions | AT+TXP=15 |
5.3 AT Command List
| Serial number | Configuration command | Description |
|---|---|---|
| 1 | AT+VOICEMODE | Set/check voice mode |
| 2 | AT+FREQ | Set/query channel frequency parameters |
| 3 | AT+TXP | Set/check transmission power |
| 4 | AT+CHANNEL | Set/query work channel |
| 5 | AT+BAUDRATE | Set/query baud rate |
| 6 | AT+PANID | Set/query private network ID |
| 7 | AT+LOCALID | Set/query local address |
| 8 | AT+DESTID | Set/query communication destination address |
| 9 | AT+VOLUME | Set/check volume |
| 10 | AT+PTT | Set/check voice message status |
| 11 | AT+MUTE | Set/check mute status |
5.3.1 AT+VOICEMODE Set/query voice mode
| Instruction | Response | Example |
|---|---|---|
| AT+VOICEMODE=<mode> | AT_OK <error description> | Send: AT+VOICEMODE=51 Return: AT_OK |
| AT+VOICEMODE? | +VOICEMODE: AT_OK <error description> | Send: AT+VOICEMODE? Return: +VOICEMODE:51 AT_OK |
5.3.2 AT+FREQ Set/query channel frequency parameters
| Instruction | Response | Example |
|---|---|---|
| AT+FREQ=<param number>:<param1>,<param2>,...,<param16> | AT_OK <error description> | Send: AT+FREQ=16:471250000,471250000,471250000,...,471250000 Return: AT_OK |
| AT+FREQ? | +FREQ:<param number>:<param1>,<param2>,...,<param16> AT_OK <error description> | Send: AT+FREQ? Return: +FREQ:16:471250000,471250000,...,471250000 AT_OK |
5.3.3 AT+TXP Set/query transmission power
| Instruction | Response | Example |
|---|---|---|
| AT+TXP=<power value> | AT_OK <error description> | Send: AT+TXP=15 Return: AT_OK |
| AT+TXP? | +TXP:<power value> AT_OK <error description> | Send: AT+TXP? Return: +TXP:15 AT_OK |
5.3.4 AT+CHANNEL Set/query working channel
| Instruction | Response | Example |
|---|---|---|
| AT+CHANNEL=<channel value> | AT_OK <error description> | Send: AT+CHANNEL=1 Return: AT_OK |
| AT+CHANNEL? | +CHANNEL: <channel value> AT_OK <error description> | Send: AT+CHANNEL? Return: +CHANNEL:AT_OK |
5.3.5 AT+BAUDRATE Set/query baud rate
| Instruction | Response | Example |
|---|---|---|
| AT+BAUDRATE=<baudrate> | AT_OK <error description> | Send: AT+BAUDRATE=115200 Return: AT_OK |
| AT+BAUDRATE? | +BAUDRATE: 115200 AT_OK <error description> | Send: AT+BAUDRATE? Return: +BAUDRATE:115200 AT_OK |
5.3.6 AT+PANID Set/query private area network ID
| Instruction | Response | Example |
|---|---|---|
| AT+PANID=<id value> | AT_OK <error description> | Send: AT+PANID=1 Return: AT_OK |
| AT+PANID? | +PANID:<id value> AT_OK <error description> | Send: AT+PANID? Return: +PANID:1 AT_OK |
5.3.7 AT+LOCALID Set/query local address
| Instruction | Response | Example |
|---|---|---|
| AT+LOCALID=<id value> | AT_OK <error description> | Send: AT+LOCALID=1 Return: AT_OK |
| AT+LOCALID? | +LOCALID: <id value> AT_OK <error description> | Send: AT+LOCALID? Return: +LOCALID:1 AT_OK |
5.3.8 AT+DESTID Set/query communication destination address
| Instruction | Response | Example |
|---|---|---|
| AT+DESTID=<param number>:<param1>,<param2>,...,<param16> | AT_OK <error description> | Send: AT+DESTID=16:1,2,3,...,16 Return: AT_OK |
| AT+DESTID? | +DESTID:<param number>:<param1>,<param2>,...,<param16> AT_OK <error description> | Send: AT+DESTID? Return: +DESTID:16:1,2,...,16 AT_OK |
5.3.9 AT+VOLUME Set/query volume
| Instruction | Response | Example |
|---|---|---|
| AT+VOLUME=<volume value> | AT_OK <error description> | Send: AT+VOLUME=1 Return: AT_OK |
| AT+VOLUME? | +VOLUME:<volume value> AT_OK <error description> | Send: AT+VOLUME? Return: +VOLUME:1 AT_OK |
5.3.10 AT+PTT Set/query voice transmission status
| Instruction | Response | Example |
|---|---|---|
| AT+PTT=<value> | AT_OK <error description> | Send: AT+PTT=1 Return: AT_OK |
| AT+PTT? | +PTT:<value> AT_OK <error description> | Send: AT+PTT? Return: +PTT:1 AT_OK |
5.3.11 AT+MUTE Set/query mute status
| Instruction | Response | Example |
|---|---|---|
| AT+MUTE=<value> | AT_OK <error description> | Send: AT+MUTE=1 Return: AT_OK |
| AT+MUTE? | +MUTE:<value> AT_OK <error description> | Send: AT+MUTE? Return: +MUTE:1 AT_OK |
5.3.12 AT+SENDB Sends data in hexadecimal format
| Instruction | Response | Example |
|---|---|---|
| AT+SENDB=<hex > | AT_OK +SEND_FINISH | Send: AT+SENDB=01020304 Return: AT_OK +SEND_FINISH |
6. Maintenance
6.1 Reflow Soldering Temperature
| Reflow soldering curve characteristics | Lead-based assembly process | Lead-free assembly process | |
|---|---|---|---|
| lowest temperature (Tsmin) | 100°C | 150°C | |
| Preheating/Keeping warm | maximum temperature (Tsmax) | 150°C | 200°C |
| time (Tsmin~Tsmax) | 60-120 seconds | 60-120 seconds | |
| heating slope (TL~Tp) | 3°C/second, maximum value | 3°C/second, maximum value | |
| liquid phase temperature (TL) | 183°C | 217°C | |
| TL above holding time | 60~90 seconds | 60~90 seconds | |
| Peak temperature of the package Tp | Users must not exceed the temperature indicated on the product's "moisture sensitivity" label. | ||
| Within the specified classification temperature (Tc) of 5°C, see the figure below. | 20 seconds | 30 seconds | |
| cooling slope (Tp~TL) | 6°C/second, maximum value | 6°C/second, maximum value | |
| Time from room temperature to peak temperature | 6 minutes, maximum | 8 minutes, maximum | |
※ The tolerance definition for the peak temperature (Tp) of the temperature curve is the upper limit set by the user.
6.2 Reflow Soldering Curve Diagram
7. Troubleshooting (FAQ)
7.1 Power-up module does not respond
- Check power supply connections and voltage levels.
- Ensure the module is correctly grounded.
- Verify that the module is not damaged due to incorrect wiring or overvoltage.
7.2 Module is easily damaged
- Please check the power supply to ensure that it is within the recommended voltage range. Exceeding the maximum voltage may cause permanent damage to the module.
- Please check the stability of the power supply to ensure that the voltage does not fluctuate significantly or frequently.
- Please ensure that anti-static measures are taken during installation and use, as high-frequency components are sensitive to static electricity.
- Please ensure that the humidity is not too high during installation and use, as some components are sensitive to humidity.
- Unless there are special requirements, it is not recommended to use the product at extremely high or low temperatures.
7.3 The sound quality is too poor
- The power supply ripple is too large. Be sure to reduce the power supply ripple by adding decoupling capacitors and EMC filter circuits.
- The audio input wiring is unreasonable. Differential design is required, and the wiring should be as close to the module pins as possible.
- There may be interference from signals of the same frequency nearby. Modify the module channel usage.
7.4 Voice intercom malfunction, no sound or static
- Check the MIC input signal on the bottom board to see if the MIC is working properly.
- Check if the speaker and its amplifier are working properly.
- Check if the headset is plugged into the headphone jack, causing the onboard microphone or speaker to stop working.
- Unplug the headset or continue repairing the faulty circuit.
7.5 Intermittent voice communication
- Wireless environment changes (co-channel interference, adjacent channel interference, antenna damage): Inspect the antenna and change the channel to avoid interference.
- EMC interference module (module accessories include high-power equipment such as motors and variable frequency drives): Add shielding covers and incorporate filter circuit design.
- Module interference with MIC circuits (an uncommon cause): Add shielding covers and incorporate filter circuit design.
- Module transmission distance reaches critical threshold, new shielding factors in the environment, adjust antenna position, replace with high-gain antenna, or relocate antenna placement.
- Network communication timing issues causing air collisions. Adjust communication strategy to avoid multiple modules sending data simultaneously.
7.6 Short transmission distance/becoming shorter
- Module transmission performance deterioration (low transmission power, decreased reception sensitivity), module damage, return to factory for repair.
- Loose, corroded, or damaged antenna, tighten antenna connection, replace antenna.
- New interference sources, prioritize channel replacement, adjust/upgrade antenna.
8. User Tips
- Ensure proper power supply voltage and stability to prevent module damage and ensure optimal performance.
- Always use anti-static measures during installation and handling of the module.
- For best communication range, ensure antennas are exposed, oriented vertically, and not obstructed by metal objects.
- When integrating the module, consider electromagnetic compatibility and keep it away from high-frequency interference sources.
9. Warranty and Support
For technical support, please contact support@cdebyte.com.
Documents and RF Setting download link: www.cdebyte.com.
For any questions or suggestions, contact info@cdebyte.com.
Address: B5 Mould Industrial Park, 199# Xiqu Ave, High tech Zone, Chengdu, Sichuan, China
Copyright ©2012-2025, Chengdu Ebyte Electronic Technology Co., Ltd.
