The Ebyte E840-TTL (4G05-DGC) 4G/LTE wireless data transmission module operates in two modes: transparent transmission mode and AT configuration mode. The previous article introduced an introductory testing tutorial and application precautions for this wireless data transmission module. This article uses the 4G/LTE wireless data transmission module as an example to introduce the configuration and application of transparent transmission mode, AT configuration mode, and high-speed serial transmission mode, enabling the 4G/LTE wireless data transmission module to achieve bidirectional transparent data transmission from the serial port to the network server through simple settings.
1. Transparent Transmission Mode
After power-on, the module operates in transparent transmission mode by default and automatically starts network connection. Once a connection is established with the server, any data received via the serial port will be transparently transmitted to the server. It can also receive data from the server, and upon receiving data from the server, the module will directly output it through the serial port. The maximum length of a single data packet supported by this LTE wireless data transmission module is 10KB. When multiple links are simultaneously connected to the server, the data packet will be sent to all four links simultaneously. The module will transparently output data whenever any network link receives data.
2. AT Mode
In AT mode, all serial port data is treated as AT commands. In transparent transmission mode, after receiving a "+++" frame, if the RX pin receives any AT command within 3 seconds, the mode switches to AT mode. In AT mode, sending AT+EXAT<CR><LF> switches to transparent transmission mode.
3. Multi-Link Protocol Distribution
This 4G/LTE wireless data transmission module supports 4-way socket connections. Each socket can be configured as a TCP Client or UDP Client. When sending data, users can use protocol transmission or transparent transmission. In protocol mode, the maximum data packet length supported per packet is 1024 bytes.
Protocol Transmission Format (Protocol transmission mode needs to be enabled; see AT command description for details)
Send: 0x55 0xFE 0xAA ID Data
Example: 55 FE AA 00 AA BB CC // 00: SOCK0 link, AA BB CC: The actual data to be transmitted by the user
Receive: 0xAA 0xFE 0x55 ID Data Length (two bytes) Data
Example: AA FE 55 00 00 03 11 22 33 // AA FE 55: Fixed header 00: SOCK0 link 00 03: Length of valid data received this time (11 22 bytes) 33: Real Data
4. High-Speed Continuous Transmission Mode
The E840-TTL (4G05-DGC) features a dedicated high-speed continuous transmission mode. In this mode, both the network and device sides can transmit data of any packet length, easily enabling file, image, and video transmission.
The 4G/LTE wireless data transmission module can configure/query the high-speed mode status via a host computer or AT commands (AT+HSPEED). Once high-speed mode is enabled, the device can transmit data of any packet length at a serial port baud rate of 460800 and below.
5. SMS Function
The E840-TTL (4G05-DGC) supports SMS sending and receiving, and remote SMS configuration (the inserted SIM card must support SMS services).
5.1. SMS Sending
In AT mode, sending AT+SMSSEND=number,data completes the SMS sending process, where number refers to the recipient's number and data refers to the data to be sent.
Demonstration is shown below:
