Table of Contents：

• 1.  Introduction
  • 1.1  What is LHT52 Temperature & Humidity Sensor
  • 1.2  Features
  • 1.3  Specification
  • 1.4  Power Consumption
  • 1.5  Storage & Operation Temperature
  • 1.6  Applications
• 2.  Operation Mode
  • 2.1  How it work?
  • 2.2  How to Activate LHT52?
  • 2.3  Example to join LoRaWAN network
  • 2.4  Uplink Payload
    • 2.4.1  Uplink FPORT=5, Device Status
    • 2.4.2  Uplink FPORT=2, Real time sensor value
      • Temperature & External Temperature:
      • Humidity:
      • Extension #
    • 2.4.3  Uplink FPORT=3, Datalog sensor value
    • 2.4.4  Uplink FPORT=4, DS18B20 ID
    • 2.4.5  Decoder in TTN V3
  • 2.5 Show data on Datacake
  • 2.6  Datalog Feature
    • 2.6.1  Unix TimeStamp
    • 2.6.2  Poll sensor value
    • 2.6.3  Datalog Uplink payload
  • 2.7  Alarm Mode
  • 2.8  LED Indicator
  • 2.9  Button
• 3.  Configure LHT52 via AT command or LoRaWAN downlink
  • 3.1  Downlink Command Set
  • 3.2  Set Password
• 4.  Battery & How to replace
  • 4.1  Battery Type and replace
  • 4.2  Power Consumption Analyze
• 5.  Sensors and Accessories
  • 5.1  Temperature Probe (AS-01)
  • 5.2  Program Converter (AS-02)
• 6.  FAQ
  • 6.1  How to use AT Command to configure LHT52
  • 6.2  AT Command and Downlink
  • 6.3  How to upgrade the firmware?
  • 6.4  How to change the LoRa Frequency Bands/Region?
  • 6.5 Why i see different working temperature for the device?
• 7.  Order Info
  • 7.1  Main Device
  • 7.2  Accessories
• 8.  Packing Info
• 9.  Support
• 10.  Reference material
• 11.  FCC Warning

1.  Introduction

1.1  What is LHT52 Temperature & Humidity Sensor

1.2  Features

• Wall Attachable.
• LoRaWAN v1.0.3 Class A protocol.
• Built-in Temperature & Humidity sensor
• Optional External Probe
• Frequency Bands: CN470/EU433/KR920/US915/EU868/AS923/AU915
• AT Commands to change parameters
• Remote configure parameters via LoRaWAN Downlink
• Firmware upgradable via program port
• Support 2 x AAA LR03 batteries.
• Datalog feature
• IP Rating: IP52

1.3  Specification

Built-in Temperature Sensor:

• Resolution: 0.01 °C
• Accuracy Tolerance: Typ ±0.3 °C
• Long Term Drift: < 0.02 °C/yr
• Operating Range: -10 ~ 50 °C  or -40 ~ 60 °C (depends on battery type, see FAQ)

Built-in Humidity Sensor:

• Resolution: 0.1 %RH
• Accuracy Tolerance: Typ ±3 %RH
• Long Term Drift: < 0.25 RH/yr
• Operating Range: 0 ~ 99.0 %RH(no Dew)

1.4  Power Consumption

LHT52 (without external sensor): Idle: 5uA, Transmit: max 110mA

LHT52 + External Temperature Probe (AS-01): Idle: 6uA, Transmit: max 110mA.

1.5  Storage & Operation Temperature

-10 ~ 50 °C  or -40 ~ 60 °C (depends on battery type, see FAQ)

1.6  Applications

• Smart Buildings & Home Automation
• Logistics and Supply Chain Management
• Smart Metering
• Smart Agriculture
• Smart Cities
• Smart Factory

2.  Operation Mode

2.1  How it work?

Each LHT52 is shipped with a worldwide unique set of LoRaWAN OTAA keys. To use LHT52 in a LoRaWAN network, user needs to input the OTAA keys in LoRaWAN network server. After this, if LHT52 is under this LoRaWAN network coverage, LHT52 can join the LoRaWAN network and start to transmit sensor data. The default period for each uplink is 20 minutes.

2.2  How to Activate LHT52?

 1.  Open enclosure from below position.

 2.  Insert 2 x AAA LR03 batteries.

 3.  Press the reset button to activate device.

User can check LED Status to know the working state of LHT52.

2.3  Example to join LoRaWAN network

This section shows an example for how to join the TheThingsNetwork LoRaWAN IoT server. Usages with other LoRaWAN IoT servers are of similar procedure.

Assume the DLOS8 is already set to connect to TTN V3 network . We need to add the LHT52 device in TTN V3 portal.  

Step 1:  Create a device in TTN V3 with the OTAA keys from LHT52.

Each LHT52 is shipped with a sticker with the default DEV EUI as below:

Enter these keys in the LoRaWAN Server portal. Below is TTN V3 screen shot:

Add APP EUI in the application.

choose to create the device manually.

Add APP KEY and DEV EUI 

Default mode OTAA

Step 2:  Use ACT button to activate LHT52 and it will auto join to the TTN V3 network. After join success, it will start to upload sensor data to TTN V3 and user can see in the panel.

2.4  Uplink Payload

Uplink payloads include two types: Valid Sensor Value and other status / control command.

• Valid Sensor Value: Use FPORT=2
• Other control command: Use FPORT other than 2.

2.4.1  Uplink FPORT=5, Device Status

Uplink the device configures with FPORT=5. Once LHT52 Joined the network, it will uplink this message to the server. After first uplink, LHT52 will uplink Device Status every 12 hours.

Example Payload (FPort=5):  

Sensor Model: For LHT52, this value is 0x09.

Firmware Version: 0x0100, Means: v1.0.0 version.

Frequency Band:

*0x01: EU868

*0x02: US915

*0x03: IN865

*0x04: AU915

*0x05: KZ865

*0x06: RU864

*0x07: AS923

*0x08: AS923-1

*0x09: AS923-2

*0x0a: AS923-3

Sub-Band: value 0x00 ~ 0x08(only for CN470, AU915,US915. Others are0x00)

BAT: shows the battery voltage for LHT52.

Ex1: 0x0B3A = 2874mV

Use can also get the Device Status uplink through the downlink command:

Downlink:  0x2301

2.4.2  Uplink FPORT=2, Real time sensor value

LHT52 will send this uplink after Device Status uplink once join LoRaWAN network successfully. And it will periodically send this uplink. Default interval is 20 minutes and can be changed.

Uplink uses FPORT=2 and every 20 minutes send one uplink by default.

Temperature:

Example Payload (FPort=2):   08 CD 02 20 7F FF 01 61 CD 4E DD

Temperature & External Temperature:

• Example1:  0x08CD/100=22.53℃
• Example2:  (0xF5C6-65536)/100=-26.18℃

If payload is: F5C6 :  (F5C6 & 8000 == 1) , temp = (F5C6 - 65536)/100 =-26.18℃

（F5C6 & 8000：Judge whether the highest bit is 1, when the highest bit is 1, it is negative）

Humidity:

• Humidity:    0x0220/10=54.4%

Extension #

Bytes for External Sensor:

2.4.3  Uplink FPORT=3, Datalog sensor value

LHT52 stores sensor value and user can retrieve these history value via downlink command. The Datalog sensor value are sent via FPORT=3.

• Each data entry is 11 bytes, to save airtime and battery, LHT52 will send max bytes according to the current DR and Frequency bands. 

For example, in US915 band, the max payload for different DR is:

1. DR0: max is 11 bytes so one entry of data
2. DR1: max is 53 bytes so devices will upload 4 entries of data (total 44 bytes)
3. DR2: total payload includes 11 entries of data
4. DR3: total payload includes 22 entries of data.

Notice: LHT52 will save 178 set of history data, If device doesn't have any data in the polling time. Device will uplink 11 bytes of 0.

See more info about the Datalog feature.

2.4.4  Uplink FPORT=4, DS18B20 ID

User can get external DS18B20 ID through the downlink command.

Downlink:  0x2302

Example Payload (FPort=4):  28 86 63 B2 00 00 00 9F

The External DS18B20 ID is 0x28 86 63 B2 00 00 00 9F

2.4.5  Decoder in TTN V3

In LoRaWAN protocol, the uplink payload is HEX format, user need to add a payload formatter/decoder in LoRaWAN Server to get human friendly string.

In TTN , add formatter as below: 

2.5 Show data on Datacake

Log in to DATACAKE, copy the API under the account

Copy and paste the TTN decoder here and save

Visual widgets please read the DATACAKE documentation

2.6  Datalog Feature

When user want to retrieve sensor value, he can send a poll command from the IoT platform to ask sensor to send value in the required time slot.

2.6.1  Unix TimeStamp

Unix TimeStamp shows the sampling time of uplink payload. format base on

User can get this time from link:  https://www.epochconverter.com/ :

For example: if the Unix Timestamp we got is hex 0x60137afd, we can convert it to Decimal: 1611889405. and then convert to the time: 2021 – Jan -- 29 Friday 03:03:25 (GMT)

2.6.2  Poll sensor value

2.6.3  Datalog Uplink payload

See Uplink FPORT=3, Datalog sensor value

2.7  Alarm Mode

Or use a downlink directly: AA010002000F0032 (See command info)

2.8  LED Indicator

• When the node is restarted, GREEN, RED and BLUE are sequentially lit.

• During OTAA Join:
  • For each Join Request uplink: the GREEN LED will blink once.
  • Once Join Successful: the GREEN LED will be solid on for 5 seconds.

• After joined, for each uplink, the BLUE LED or GREEN LED will blink once.
  • BLUE LED when external sensor is connected
  • GREEN LED when external sensor is not connected

• For each success downlink, the PURPLE LED will blink once

• Power off/on LHT52
• Press reset button of LHT52.
• Send an AT Command: AT+CLPM=1

2.9  Button

Press the button LHT52 will reset and join network again.

3.  Configure LHT52 via AT command or LoRaWAN downlink

Use can configure LHT52 via AT Command or LoRaWAN Downlink.

• AT Command Connection: See FAQ.

• LoRaWAN Downlink instruction for different platforms: IoT LoRaWAN Server

There are two kinds of commands to configure LHT52, they are:

• General Commands:

These commands are to configure:

• General system settings like: uplink interval.

• LoRaWAN protocol & radio-related commands.

They are the same for all Dragino Devices which supports DLWS-005 LoRaWAN Stack(Note**). These commands can be found on the wiki: End Device Downlink Command

• Commands special design for LHT52

These commands are only valid for LHT52, as below:

3.1  Downlink Command Set

3.2  Set Password

Feature: Set device password, max 9 digits.

AT Command: AT+PWORD

Downlink Command:

No downlink command for this feature.

4.  Battery & How to replace

4.1  Battery Type and replace

LHT52 uses 2 x AAA LR03(1.5v) batteries. If the batteries running low (shows 2.1v in the platform). User can buy generic AAA battery and replace it.

Note: 

1.  The LHT52 doesn't have any screw, use can use nail to open it by the middle.

2.  Make sure the direction is correct when install the AAA batteries.

4.2  Power Consumption Analyze

Dragino battery powered product are all runs in Low Power mode. We have an update battery calculator which base on the measurement of the real device. User can use this calculator to check the battery life and calculate the battery life if want to use different transmit interval.

Instruction to use as below:

Step 1:  Downlink the up-to-date DRAGINO_Battery_Life_Prediction_Table.xlsx from:

https://www.dragino.com/downloads/index.php?dir=LoRa_End_Node/Battery_Analyze/

Step 2:   Open it and choose

• Product Model
• Uplink Interval
• Working Mode

And the Life expectation in difference case will be shown on the right.

5.  Sensors and Accessories

5.1  Temperature Probe (AS-01)

External Temperature Probe base on DS18B20. (note: Default Package doesn't include AS-01)

External Temperature Probe (AS-01): 

• Resolution: 0.0625 °C
• ±0.5°C accuracy from -10°C to +85°C
• ±2°C accuracy from -55°C to +125°C
• Operating Range: -55 °C ~ 125 °C
• Cable Length: 2 meters

5.2  Program Converter (AS-02)

AS-02 is an optional accessory, it is USB Type-C converter. AS-02 provide below feature:

1. Access AT console of LHT52 when used with USB-TTL adapter. See this link.
2. Update firmware to LHT52 when used with DAP-Link adapter.  See this link.

6.  FAQ

6.1  How to use AT Command to configure LHT52

LHT52 supports AT Command set. User can use a USB to TTL adapter plus the Program Cable to connect to LHT52 for using AT command, as below.

Connection:

• USB to TTL GND <--> Program Converter GND pin
• USB to TTL RXD  <--> Program Converter D+ pin
• USB to TTL TXD  <--> Program Converter A11 pin

It is also possible to connect using DAPLink

• USB to DAP-LINK GND <--> Program Converter GND pin

• USB to DAP-LINK RXD  <--> Program Converter D+ pin

• USB to DAP-LINK TXD  <--> Program Converter A11 pin

6.2  AT Command and Downlink

6.3  How to upgrade the firmware?

LHT52 requires a program converter to upload images to LHT52, which is used to upload image to LHT52 for:

• Support new features
• For bug fix
• Change LoRaWAN bands.

6.4  How to change the LoRa Frequency Bands/Region?

User can follow the introduction for how to upgrade image. When download the images, choose the required image file for download.

6.5 Why i see different working temperature for the device?

The working temperature range of device depends on the battery user choose.

• Normal AAA Battery can support -10 ~ 50°C working range.
• Special AAA battery can support -40 ~ 60 °C working range. For example: Energizer L92

7.  Order Info

7.1  Main Device

• AS923: LoRaWAN AS923 band
• AU915: LoRaWAN AU915 band
• EU433: LoRaWAN EU433 band
• EU868: LoRaWAN EU868 band
• KR920: LoRaWAN KR920 band
• US915: LoRaWAN US915 band
• IN865:  LoRaWAN IN865 band
• CN470: LoRaWAN CN470 band

7.2  Accessories

Note: below accessories are not include in the main device package, need to order separately.

Temperature Probe: AS-01

Program Converter: AS-02

8.  Packing Info

Package Includes:

• LHT52 Temperature & Humidity Sensor x 1

9.  Support

• Support is provided Monday to Friday, from 09:00 to 18:00 GMT+8. Due to different timezones we cannot offer live support. However, your questions will be answered as soon as possible in the before-mentioned schedule.
• Provide as much information as possible regarding your enquiry (product models, accurately describe your problem and steps to replicate it etc) and send a mail to support@dragino.com.

10.  Reference material

• Datasheet, photos, decoder, firmware

11.  FCC Warning

This device complies with part 15 of the FCC Rules.Operation is subject to the following two conditions:

(1) This device may not cause harmful interference;

(2) this device must accept any interference received,including interference that may cause undesired operation.