Dragino - LHT65

Manufacturer: Dragino
Product: LHT65

The LHT65 includes a built-in SHT20 temperature/humidity sensor and a jack to connect an external sensor e.g. a temperature sensor.

Specifications
Documents
Ordering Info
Adding the Device to TTN
Optional Settings
1. Change sampling interval
  1. Examples

Specifications

indoor device (external sensor placement possible)
Price ca. CHF 50.- (15.07.2020)
Built-in sensors
- Temperature, -40 … +80 [°C], ± 0.8
- relative Humidity, 0 … 99.9 [%rH], ± 10 %rH
External sensor
- Temperature, -55 … 125 [°C], ± 0.5 °C between -10 … 85 °C, ± 2 °C between -55 … 125 °C
Power Supply: 1 battery, 3.0 V, 2400 mAh (CR17450), Li-MnO₂
- Expected life time: 8 … 10 years at roomtemperature
Min voltage: 2.45 V
Size: 43 × 93 × 28 mm
Weight: 116 g

Documents

Ordering Info

Part Number: LHT65-XX-YY
- XX is frequency band
- YY is external sensor
Version with external temperature sensor: LHT65-EU868-E1
Ordering Link

Adding the Device to TTN

Handler device information

Each device is shipped with a sticker with the default keys on it:

For an OTAA (over the air activation) only the DEV EUI, APP EUI and APP KEY are required.

Device Registration

Before a device can communicate via “The Things Network” we need to register it with an application.
The dragino sensors use the so called “Over The Air Activation” (OTAA) and for a secure communication we will need to register the beforehand mentioned keys.

Log in and open the application to which you wish to add a device
Under Settings > EUIs click (+) add EUI
Click the pen symbol and paste the before copied APP EUI from the sticker and hit the button Add EUI
Click Devices > register device
- For Device ID, choose a unique ID of lower case, alphanumeric characters and nonconsecutive - and _.
- For Device EUI paste the copied “DEV EUI from the sticker
- For App Key press the pen icon and enter the APP KEY from the sticker
- Select the correct App EUI which we entered in step 3
- press the button Register
Now we have to restart the device manually by pressing the ACT button on the bottom of the device. fast press ACT 5 times -> Off , press ACT for more than 3 seconds -> On
The device should log in and you should see a green circle as Status in the tab Device Overview.

Device Configuration

Now you can see the incoming telegrams in the tab Data, but their content, the payload, is cryptic…!
We need to tell the “The Things Network” where to find e.g. the temperature etc. in these cryptic numbers and letters. We can do that with configuring a “Payload Decoder Function”.

Log in and open the application
Select the tab Payload Formats > decoder and copy/paste the following code:

function Decoder(bytes, port) {
//Payload Formats of LHT65 Device
  return {
    
       //External sensor
       Ext_sensor:
       {
         "0":"No external sensor",
         "1":"Temperature Sensor",
         "4":"Interrupt Sensor send",
         "5":"Illumination Sensor",
         "6":"ADC Sensor",
         "7":"Interrupt Sensor count",
       }[bytes[6]&0x7F],
       
       //Battery,units:V
       BatV:((bytes[0]<<8 | bytes[1]) & 0x3FFF)/1000,
       
       //SHT20,temperature,units:â„ƒ
       TempC_SHT:((bytes[2]<<24>>16 | bytes[3])/100).toFixed(2),
       
       //SHT20,Humidity,units:%
       Hum_SHT:((bytes[4]<<8 | bytes[5])/10).toFixed(1),
       
       //DS18B20,temperature,units:â„ƒ
       TempC_DS:
       {
         "1":((bytes[7]<<24>>16 | bytes[8])/100).toFixed(2),
       }[bytes[6]&0xFF],       
       
       //Exti pin level,PA4
       Exti_pin_level:
       {
         "4":bytes[7] ? "High":"Low",
       }[bytes[6]&0x7F], 
       
       //Exit pin status,PA4
       Exti_status:
       {
         "4":bytes[8] ? "True":"False",
       }[bytes[6]&0x7F],    
       
       //BH1750,illumination,units:lux
       ILL_lux:
       {
         "5":bytes[7]<<8 | bytes[8],
       }[bytes[6]&0x7F],  

        //ADC,PA4,units:V
        ADC_V:
       {
         "6":(bytes[7]<<8 | bytes[8])/1000,
       }[bytes[6]&0x7F],  
       
        //Exti count,PA4,units:times
        Exit_count:
        {
          "7":bytes[7]<<8 | bytes[8],
        }[bytes[6]&0x7F],  
        
        //Applicable to working mode 4567,and working mode 467 requires short circuit PA9 and PA10
        No_connect:
        {
          "1":"Sensor no connection",
        }[(bytes[6]&0x80)>>7],  
  };
}

Copy/Paste the following test payload into the field Payload and press Test
```
CC B7 0A 6C 03 9F 01 0A 85 7F FF
```
You should see the following result
```
{
  "BatV": 3.255,
  "Ext_sensor": "Temperature Sensor",
  "Hum_SHT": "92.7",
  "TempC_DS": "26.93",
  "TempC_SHT": "26.68"
}
```
- BatV -> battery voltage [V]
- Ext_sensor -> connected external sensor
- Hum_SHT -> Humidity internal sensor [%rH]
- TempC_DS -> Temperature external sensor [°C]
- TempC_SHT -> Temperature internal sensor [°C]
Press save payload functions

Now you should be able to see the decoded data of your sensor in the tab Data.
Trigger a new telegram by pressing the ACT-button on the dragino LHT65 for a short time (> 1s and < 3s).
The dragino LHT65 sends a telegram once every 10 minutes.

Optional Settings

Change sampling interval

To change the sampling interval, you have to send the device configuration telegrams (Downlink-Messages) The time interval in minutes at which the sensor queries the current values.

In the TTN Console on the device view, select the device and change to the tab Messaging, select Downlink
Change the FPort to 2
Copy/paste the payload, e.g. 0100012C into the Payload field to set interval to 5 minutes
Press Send
In the Data tab you should now see the scheduled telegram. The wisely sensor only receives downlink data after a transmission. Therefore start a transmission by pressing the button on the back of the sensor (push once short, green led will illuminate)

Examples

‘0100’ is an identifier, the rest represents the sampling interval in hex

5 Minutes Interval: ‘0100012C’ (300s in hex are ‘012C’)
15 Minutes Interval: ‘01000384’ (900s in hex are ‘0384’)
60 Minutes Interval: ‘01000E10’ (3600s in hex are ‘0E10’)