HM-TRLR-S Series 100mW LoRa Transceiver

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HM-TRLR-S series is a low cost, high performance transparent transceiver operating at 433/915MHz. It is LoRa/FSK/GFSK/OOK modulation variety. It features small size, high output power, high sensitivity, long transmission distance and most of the parameters can be set via the command. Receive and send data to automatically switch. Use generic UART interface. It is easy to realize the wireless data transmission if provided with the UART data. It is flexible for the users to set the parameters of UART baud rate, output power, data rate, frequency select, modulation mode select etc. It is your ideal choice for designing wireless data transmission products which can be widely used on wireless data transmission field.


  • Low cost, high performance, high reliability
  • LoRa/FSK/GFSK/OOK modulation, 2-way half –duplex communication, strong anti-interfere
  • 433/915MHz ISM band, globally license free.
  • Maximal output power100mW(20dBm), output power adjustable between 2-20dBm
  • LORA Sensitivity -139dBm
  • Supply current for Tx 130mA@20dBm, 35mA@13dBm
  • Supply current for Rx 16mA
  • Low current sleep mode 2uA
  • Standard UART interface, extendable to RS232 or other interface
  • Operation frequency can be configured, acceptable for several modules working in different frequency with no disturbance on each other.
  • RF parameters as needed, users can be modulated by software.
  • Easily use, auto exchange on communication & transceiver
  • Communication speed 1.2kbps -115.2kbps,can be modulated through software
  • Afford Sleep control signal,user self control work duty cycle
  • With LED indicator
  • Longer transmission distance,over 5Km in open air
  • Small size 16*20*2mm,10PIN SMD package,easy for assembly .
  • Tuning free
  • Accord FCC, ETSI standard


  • Remote control, remote measurement
  • Data collection
  • Wireless meter
  • Access control
  • IT household appliance
  • Intelligence household appliance
  • Identification system

Pin Description

433,915transceiver2 .jpg

VCC—— Power supply,2.4-3.6V DC power, recommendation 3.3V DC power

TXD—— Data transmission

GND—— Ground

RXD—— Data receiving

CONFIG——Set low for configuration mode, while set high for communication

SLEEP——Set low for normal mode for data transceiver , while back to sleep if set high


RESET——Reset trigger input, Active low

ANT—— Input/output interface with 50 ohm antenna

GND—— Ground

Maximum Specification

433,915transceiver Specification .jpg


433,915transceiverParameter.jpg 433,915transceiver Parameter02.png

Typical Application


433,915transceiver application1.jpg

As in the above Figure, connect the TXD pin of HM-TRLR-S with UART RXD Pin of MCU, connect the RXD pin of HM- TRLR-S with the UART TXD pin of MCU. Then the CONFIG/SLEEP/RESET/STATUS of HM-TRLR-S connects with GPIO of MCU.

HM-TRLR-S extends to RS232

433,915transceiver application2.jpg

You can extend the HM-TRLR-S to RS232 by adding the MAX3232, and then you can directly connect the COM to the PC.

Mechanical Dimension



Application Part

Modulation Mode

HM-TRLR series transparent transceiver module can work in the traditional FSK / GFSK modulation mode, as well as in LoRa modulation mode. According to the application requirements, users can switch the modulation mode conveniently. Using principles: use FSK / GFSK modulation when requiring large quantities of high-rate data transmission; use the LoRa modulation when long-distance data transmission is needed.

Operating Mode

HM-TRLR series transparent transceiver module has three kinds of operating mode: Running Mode、Configuration Mode and Sleep Mode. When the module is in Running Mode, users can send and receive data; when the module is in the Configuration Mode, users can change the formulation parameters according to the need via AT commands; Sleep Mode allows the module to enter into a low power consumption status.

  • Running Mode Timing Diagram

Running Mode Timing Diagram.png

Note:When the modulation pattern is LoRa and the HM - TRLR receive buffer is full, the STATUS pin will output a low level.

  • Configuration Mode Timing Diagram

Configuration Mode Timing Diagram.jpg

Note:The module enters into the Configuration Mode by pulling up the CONFIG pin. If the STATUS output is at low level, users can send AT commands to revise the parameters.

  • Sleep Mode Timing Diagram

Sleep Mode Timing Diagram.png

Note: Sleep mode is controlled by SLEEP pin

  • Reset Timing Diagram

Reset Timing Diagram.png

Channel Frequency

Different model of HM-TRLR module has different frequency band, each frequency band is divided into 16 channels, and frequency details are as below:

Channel Frequency.png

Transfer rate

When HM-TRLR module works in FSK modulation, the air rate can self-adapt to serial baud rate. Theoretically, it is able to transfer wireless data, it’s better to transmit in batches to avoid interference in the air if the data package is large. When HM-TRLR module works in LoRa modulation, the transmission rate depends on the Signal Bandwidth, the Spreading Factor, FEC coding rate and the Payload Length. The sensitivity of receiver is only related to the Signal Bandwidth and the Spreading Factor. The following table shows the relationship between the transmission rate and parameters:

Test conditions:

1. Supply voltage = 3.3 V

2. Temperature = 25° C

3. CRC on payload enabled

4. Payload length = 64 bytes

5. Coding Rate = 1


Hopping Frequency Spread Spectrum (HFSS)

When HM-TRLR module works in LoRa modulation, it has the function of HFSS, which can be applied to the occasions where the time of frequency occupancy is limited. For example, in the United States, the frequency of the ISM segments 902-928, when the data transmission time of a packet exceeds the frequency occupancy time limits, you can use frequency-hopping technology, there are two parameters need to be set: Hopping Cycle and Frequency Stepping.

Calculating Formula:

 HoppingPeriod(ms) = ( 2SF/BW) * FreqHoppingValue
 SF = SpreadingFactor
 BW = SingnalBandWidth
 FreqHoppingValue = 1~255
 FreqStep = 61Hz*FreqStepValue
 FreqStepValue = 0~65535

Node ID Function with FSK

When HM-TRLR works in FSK modulation, you can set the Node ID, when the function of the Node ID is turned on, the first byte the transmitter sends is the Node ID of the receiver, and the receiver receives only the Node ID that matches with it. When the function of Node ID is turned on, the module can start the Broadcast ID function; when the Broadcast starts, the receiver can receive data both from the Node ID and the Broadcast.

Note:When this function is on, the interval between the two frames of data is not less than the Td; the first byte of each frame of data is the Node ID or Broadcast ID.

Td (Time Delay)

TD for FSK modulation

Td is the delay of time between module 1(RXD pin received data) and module 2 (TXD pin transfer data). The time delay (Td) will change with different baud rate, as shown below:



Td for LoRa Modulation

As air data is transmitted in batches when the module is in LoRa Modulation, if the data exceeds Payload Length and the air rate is less than serial rate, the data receivered will be intermittent. In the transmitter, you can check whether the HM-TRLR buffer is full or not through the STATUS pin.

Air rate is higher than the serial rate, as shown below:


Air rate is less than the rate of the serial rate, as shown below:

Trxd 2.png

Testing Conditions:

1. Spread Factor = 9

2. Singal Band Width = 250 kHz

3. Code Rate = 1

4. PayLoad = 32 bytes

Baud rate 2.png

HM-TRLR-S AT Instruction Manual


When IO port is triggered by peripherals, the HM-TRLR-S module will enter into the Configuration Mode, you can revise the performance parameter by sending AT commands through serial ports.

Command Syntax

Command will be represented by capitalized ASCII and ending with <CR>, when the module receives the commands, it will interpret and respond to commands

Command Set Format

Command Set is used to set the parameters of peripherals for HM-TRLR-S transparent transceiver module; it is begins with capital AT, followed by the command type and parameters.

  Command Format:AT+Cmd Type=Para1, Para2…<CR>
  Command Return Succeed:  OK<CR>
  Command Return Failed:  ERROR: n<CR>

Read Command Format

Read Command is used to read the command of peripherals for HM-TRLR-S transparent transceiver module; it begins with capital AT, and followed by the command type and a question mark.

  Command Format:AT+CmdType=? <CR>
  Command Return Succeed:  CmdType: Para1, Para2…<CR>
  Command Return Failed:  ERROR: m<CR>

Parameter interpretation when an error returns

When an execution error is returned, the modules will return ERROR:m.

Execution error.png

Command Type

Baud Rate Command

Serial baud rate refers to the communication rate between the module and its peripherals, when the setup is complete, the new baud rate takes effect immediately, and the baud rate of the peripherals should be based on the new module communication.

AT+SPR (SerialPortRate) Command

AT SPR Command1.png

Parameters Table

Parameters Table.png

Serial check mode command

Modules and peripherals using UART mode, their check mode can be set, when the setup is completed, the new formulation will come into effect immediately.

AT+SPC(SerialPortCheck) Command

ATSPC Command.png

Parameters Table

Parameters Table2.png

Transmit power command

Transmitting power can be revised, when the setup is completed, it will come into effect when you exit the Configuration Mode.

AT+POWER Command

AT POWER Command.png

Parameters Table

Parameters Table 3.png

The selection of Communication Channel

Channel selection means the frequency point that RF (Radio Frequency) works, there are 16 channels available, and only modules with the same channel can communicate between each other.

ATCS Command.png

Parameters Table

Parameters Table4.png

Set up Sync Word

Module Sync word can be set with1 to 8 bytes, and the modules with the different Sync Words can’t communicate with each other.

AT+SYNW Command

ATSYNW Command.png

Parameters Table

Parameters Table5.png

Example 1: If the Sync Word is 0x12,0x34,0xAB, 0xEF, that is 4 byte, and the transmitting AT Command is “AT+SYNW=1234ABEF\r\n”.

Set up Sync Word Length

Module Sync word can be set with1 to 8 bytes, and the modules with the different Sync Words can’t communicate with each other. It is suggested to set more than 2 bytes, when it is set as 0, there will be no Sync Word.

AT+SYNL Command

AT SYNL Command.png

Parameters Table

Parameter Table6.png

Node Function

In FSK Mode, you can set the Node Function for the module

AT+NODE Command

AT NODE Command.png

Parameters Table

Parameter Table7.png

Node ID

In FSK Mode, you can set the number of Node ID of the module.

AT+NID Command

AT NID Command.png

Parameters Table

Parameter Table8.png

Broadcast ID

In FSK mode, you can set the number of Broadcast ID of the module.

AT+BID Command

AT BID Command.png

Parameters Table

Parameter Table9.png

LoRa CRC allows command

Opens Air Data transmission or closes CRC

AT+LR Command

AT LR Command.png

Parameter Table10.png

LoRa transmission frequency bandwidth selection command

When the module is working in LoRa mode, the transmitting signal bandwidth can be set according to the needs of the module, the wider the bandwidth is, the faster the air rate will be.

AT+LRSBW(SignalBandWidth) Command

AT LRSBW Command.png

Parameter Table

Parameter Table16.png

LoRa spreading factor selection command

When the module is working in LoRa Mode, the spreading factor can be set according to the needs of module, the higher the spreading factor is, the higher the reception sensitivity will be, and the slower the speed will be.

AT+LRSF (SpreadingFactor) Command

AT LRSF Command.png

Parameter Table

Parameter Table11.png

LoRa Pre-error -correction -code selection command

When the module is working in LoRa mode, data transmission adopts the pre- error-correction –coding- format; this command is set by choosing its Coding Rate.

AT+LRCR (CodingRate) Command

AT LRCR Command.png

Parameter Table

Parameter Table12.png

LoRa hopping frequency allowed command

When the module is working in LoRa mode, frequency hopping function is allowed.

AT+LRHF (HFSS) Command

AT LRHF Command.png

Parameter Table

Parameter Table13.png

LoRa Payload length setting command

When the module is working in LoRa mode, data is transmitted in batches, this command is used to set the packetlength.

AT+LRPL (PacketLenth) Command

AT LRPL Command.png

Parameter Table

Parameter Table14.png

LoRa hopping frequency cycle command

When the module is working in LoRa Mode, you can set the cycle of hopping frequency.

AT+LRHPV (HoppingPeriodValue) Command


Parameter Table

Parameter Table15.png

LoRa hopping frequency stepping command

When the module is working in LoRa Mode, you can set the stepping of hopping frequency.

AT+LRFSV (FrequencyStepValue) Command

AT LRFSV Command.png

Parameter Table

Parameter Table17.png

Mode Command

This command can change the modulation mode of HM-TRLR

AT+MODE Command

AT MODE Command.png

Parameter Table

Parameter Table18.png

Frequency Band Command

This command can change the working frequency band of HM-TRLR.

AT+BAND Command

ATBAND Command.png

Parameter Table

Parameter Table19.png

Test Command

Connection test

AT Command

AT Command.png

Save parameters

When parameters changes with the AT commands, HM-TRLR will not save the parameters to the Flash Memory automatically, HM-TRLR will read the parameters Flash Memory after reset. Therefore it is necessary for the user to save the new parameter values; you can use this command to write the parameters changed previously in Flash Memory. Warning: Due to the time of writing Flash memory is limited, Flash Memory may be damaged if you keep rewriting, and you can rewrite no more than10000 times.

AT&W Command

AT W Command.png

Default setting

  • HM-TRLR-S-433 the default value of the module

Default setting.png

  • HM-TRLR-S-915 The default value of the module

Default value.png

How to get it

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