Digital Communication Module MT-877

Digital Communication Module MT-877 Details

Product Overview: MT-877 Wireless Data Transmission Module

The MT-877 is a highly integrated, low-power, half-duplex wireless data transmission module. It utilizes a high-performance RF chip and a high-speed microcontroller. The module operates in a transparent transmission mode, requiring no custom configuration or transmission protocols from the user, making it suitable for transmitting data packets of any size. It features a compact form factor, wide operating voltage range, and is designed for easy integration into embedded systems.

Key Features

• Frequency Range: 430-462 MHz (ISM Band)

• Modulation: GFSK

• Transmission Power: 500mW (27dBm)

• Receiver Sensitivity: -123dBm

• Transmission Distance: Up to 3000 meters (at 1200bps)

• Channels: 16 user-configurable communication channels

• Data Interface: UART/TTL, RS-232, RS-485

• Baud Rates: 1200, 2400, 4800, 9600, 19200, 38400 bps

• Data Buffer: Large 512-byte buffer

• Transmission Mode: Transparent transmission

• Reliability: Built-in Watchdog Timer for long-term stability; supports checksum or CRC error checking with retransmission.

• Dimensions: 63mm x 43mm x 15mm (excluding antenna connector)

Applications

• Automatic meter reading systems (water, electricity, gas, heating)

• Intelligent Wireless PDA terminals

• Wireless queuing equipment

• Security and theft alarm systems

• Smart card systems

• Automation control for medical and electronic instruments

• Intelligent teaching equipment

• Smart home appliance and lighting control

• Wireless scales and electronic weighing systems with data transmission

Functional Description

1. Transparent Data Transmission
The module uses a transparent transmission method. To ensure reliability, it supports the addition of a checksum or CRC for error detection, with automatic retransmission of corrupted data packets.

2. Data Packet Length Recommendation
Although the module has a 512-byte buffer and can theoretically send long packets (especially when the air data rate is higher than the UART rate), it is strongly recommended to keep packet lengths between 60 to 100 bytes, and generally not exceeding 120 bytes.

Rationale: In conditions with a bit error rate (BER) of 10⁻⁴, sending a single large 1KB (10,000-bit) packet would almost certainly contain an error. By splitting the data into smaller packets (e.g., 10 packets of 100 bytes), only a small fraction may be affected. An Automatic Repeat Request (ARQ) protocol can then be used to retransmit only the erroneous packets, ensuring reliable data transfer with minimal efficiency loss.

3. Parameter Configuration
Unlike traditional modules that use physical jumpers, the MT-877 is configured via a serial interface. This method is more reliable (avoiding contact issues) and flexible, allowing parameters to be easily embedded into user microcontroller programs or host software.

4. Operating Modes

• Normal Mode: Upon power-up, the module enters receive mode and is ready for data transmission.

• Sleep Mode: Upon power-up, the module remains in a low-power sleep state. It must be awakened by pulling the SLE pin high before it can send or receive data.

Pin Definitions (J1 Connector)

Power Supply Requirements

• Voltage: 4.5V to 5.5V DC (for 5V module variant).

• Current: The power supply must be capable of providing >500mA.

• Quality: A high-quality power supply with low ripple is essential for stable operation.