1. ISP:     upgrade mode, device won't have any signal in this mode. but ready for upgrade firmware. LED won't work. Firmware won't run.

2. Flash:  work mode, device starts to work and send out console output for further debug

Following is an example for how to join the TTN V3 LoRaWAN Network. Below is the network structure; we use the LG308  as a LoRaWAN gateway in this example.  

​

Step 1: Create a device in TTN with the OTAA keys from LSN50.

Each LSN50 is shipped with a sticker with the default device EUI as below:

LSN50 has different working mode for the connections of different type of sensors. This section describes these modes. Use can use the AT Command AT+MOD to set LSN50 to different working modes.

For example:

 AT+MOD=2    // will set the LSN50 to work in MOD=2 distance mode which target to measure distance via Ultrasonic Sensor.

NOTE:

1. Some working modes has payload more than 12 bytes, The US915/AU915/AS923 frequency bands' definition has maximum 11 bytes in DR0. Server sides will see NULL payload while LSn50 transmit in DR0 with 12 bytes payload.

2. All modes share the same Payload Explanation from HERE.

3. By default, the device will send an uplink message every 5 minutes.

In this mode, uplink payload includes in total 11 bytes. Uplink packets use FPORT=2.

Please use firmware version > 1.6.5 when use MOD=2, in this firmware version, user can use LSn50 v1 to power the ultrasonic sensor directly and with low power consumption.

This mode is supported in firmware version since v1.6.2.  Please use v1.6.5 firmware version so user no need to use extra LDO for connection.

In this mode, the device will work in counting mode. It counts the interrupt on the interrupt pins and sends the count on TDC time.

Connection is as below. The PIR sensor is a count sensor, it will generate interrupt when people come close or go away. User can replace the PIR sensor with other counting sensors.

Note: LoRaWAN wireless transmission will infect the PIR sensor. Which cause the counting value increase +1 for every uplink. User can change PIR sensor or put sensor away of the LSN50 to avoid this happen.

           Power loss or restart will reset the count

The payload decoder function for TTN V3 are here:

LSN50 TTN V3 Payload Decoder:  https://github.com/dragino/dragino-end-node-decoder

Check the battery voltage for LSN50.

Ex1: 0x0B45 = 2885mV

Ex2: 0x0B49 = 2889mV

The ADC pins in LSN50 can measure range from 0~Vbat, it use reference voltage from STM32. If user need to measure a voltage > VBat, please use resistors to divide this voltage to lower than VBat, otherwise, it may destroy the ADC pin.

Note: minimum VBat is 2.5v, when batrrey lower than this value. Device won't be able to send LoRa Uplink.

The ADC monitors the voltage on the PA0 line, in mV.

Ex: 0x021F = 543mv,

 Example1:  Reading an Oil Sensor (Read a resistance value):

 Interrupt connection method:

Example to use with door sensor : (Requires firmware > 1.5.1)

The door sensor is shown at right. It is a two wire magnetic contact switch used for detecting the open/close status of doors or windows.

When the two pieces are close to each other, the 2 wire output will be short or open (depending on the type), while if the two pieces are away from each other, the 2 wire output will be the opposite status. So we can use LSN50 interrupt interface to detect the status for the door or window.

 Below is the installation example:

Fix one piece of the magnetic sensor to the door and connect the two pins to LSN50 as follows:

Install the other piece to the door. Find a place where the two pieces will be close to each other when the door is closed. For this particular magnetic sensor, when the door is closed, the output will be short, and PB14 will be at the VCC voltage.

Door sensors have two types:  NC (Normal close) and NO (normal open). The connection for both type sensors are the same. But the decoding for payload are reverse, user need to modify this in the IoT Server decoder.

When door sensor is shorted, there will extra power consumption in the circuit, the extra current is 3v3/R14 = 3v2/1Mohm = 0.3uA which can be ignored.

The above photos shows the two parts of the magnetic switch fitted to a door.

The command is:

AT+INTMOD=1       //(more info about INMOD please refer AT Command Manual. )

Below shows some screen captures in TTN V3:

The PB6(SCL) and PB7(SDA) are I2C interface lines. You can use these to connect to an I2C device and get the sensor data.

We have made an example to show how to use the I2C interface to connect to the SHT20 Temperature and Humidity Sensor. This is supported in the stock firmware since v1.5 with AT+MOD=1 (default value).

Notice: Different I2C sensors have different I2C commands set and initiate process, if user want to use other I2C sensors, User need to re-write the source code to support those sensors. SHT20 code in LSN50 will be a good reference.

Below is the connection to SHT20/ SHT31. The connection is as below:

The LSN50 v1.5 firmware supports ultrasonic sensor (with AT+MOD=2) such as SEN0208 from DF-Robot. This Fundamental Principles of this sensor can be found at this link: https://wiki.dfrobot.com/Weather_-_proof_Ultrasonic_Sensor_with_Separate_Probe_SKU___SEN0208

The LSN50 detects the pulse width of the sensor and converts it to mm output. The accuracy will be within 1 centimeter. The usable range (the distance between the ultrasonic probe and the measured object) is between 24cm and 600cm.

The picture below shows the connection:

Since firmware v1.6.3, The 5V output time can be controlled by AT Command.

AT+5VT=1000

Means set 5V valid time to have 1000ms. So the real 5V output will actually have 1000ms + sampling time for other sensors.

By default the AT+5VT=500. If the external sensor which require 5v and require more time to get stable state, user can use this command to increase the power ON duration for this sensor.

The working MOD info is contained in the Digital in & Digital Interrupt byte (7^th Byte).

User can use the 3^rd ~ 7^th   bit of this byte to see the working mod:

Case 7^th Byte >> 2 & 0x1f:

User can configure LSN50 via AT Commands or LoRaWAN Downlink Commands

There are two kinds of Commands:

       AT+MOD=2        // Set work MOD =2. (1: IIC mode, 2: Distance mode, 3: 3ADC mode, 4: 3DS18B20 mode, 5: weight mode)

       AT+MOD=?      //  Get current work MOD

       AT+INTMOD=2        // Set INTMOD =2. (0: Disable, 1:falling or rising, 2: falling, 3: rising)

       AT+INTMOD=?      //  Get current INTMOD

       AT+5VT=1000     // Set 5v open time to 1000ms

       AT+5VT=?          //  Check current 5v open duration

       AT+WEIGAP=403.0       // Set GAP Value =403.0  (response: Weight: xx g)

       AT+WEIGAP=?            //  Get current GAP Value

       AT+DECRYPT=1       // The payload is uploaded without encryption

       AT+DECRYPT=0       //  Encrypt when uploading payload (default)

       AT+GETSENSORVALUE=0      // The serial port gets the reading of the current sensor

       AT+GETSENSORVALUE=1      //  The serial port gets the current sensor reading and uploads it.

Resets the downlink packet count:

• AT Command:

When the limit bytes are exceeded, upload in batches:

• AT Command:

• Downlink Payload:

0x21 00 01          // Set  the DISMACANS=1

Copy downlink to uplink:

• AT Command:

Example: aa xx xx xx xx         // aa indicates whether the configuration has changed, 00 is yes, 01 is no; xx xx xx xx are the bytes sent.

For example, sending 11 22 33 44 55 66 77 will return invalid configuration 00 11 22 33 44 55 66 77.

For example, if 01 00 02 58 is issued, a valid configuration of 01 01 00 02 58 will be returned.

Query version number and frequency band 、TDC:

• Downlink: 26 01     //  Downlink 26 01 can query device upload frequency, frequency band, software version number, TDC time.

Example：

Add rejoin feature if device offline: (Since V1.8.0)

• AT Command:

AT+DDETECT=<Flag>,<ACK_Timout_1>,<ACK_Timout_2>    (Default Value: AT+DDETECT=1,1440,2880)

Flag:   1 Enable online detect, 0: Disable online detect

ACK_Timout_1:  Unit: min

ACK_Timout_2:  Unit: min

Example: AT+DDETECT=1,1440,2880

Enable Online Detect, if end node doesn't receive any downlink within ACK_Timout_1( 1440 minutes or 24 hours). End node will use confirmed uplink to send packets during ACK_Timout_1 (the 24th hour) to ACK_Timout_2 ( the 48th hour).

If from the 24th to 48th hour, end node got an downlink from server, it will switch back to unconfirmed uplink. end node will restart ACK_Timout_1.

If from the 24th to 48th hour, end node still not got any downlink, means device doesn't get ACK in 48 hours. Device will process rejoin, rejoin request interval is AT+RJTDC period. For AU915/ US915, device will use the sub-band used for last join. 

• Downlink: 0x32 01 05A0 0B40 

  0x01 : Flag

  0x05A0: ACK_Timout_1

  0x0B40: ACK_Timout_2

   

Add new feature to control NBTrans for unconfirmed uplink mode:

• AT Command:

 AT+SETMAXNBTRANS=value1,value2         // NBTrans specified how many re-transmission for each packet. If LoRaWAN LinkADR from server set NBTrans to high value. The battery will consume fast. 

AT+SETMAXNBTRANS=value1,value2    Default Value: AT+SETMAXNBTRANS=1,0

value1:  Set max NBTrans. For example, if value1(NBTrans)=1, end node set NBTrans max to 1 , even downlink LinkADR request end node to set NBTrans to higher value such as 6. 

value2:  0: uplink fcnt doesn't change for each NBTrans;  1: uplink fcnt increase by 1 for each NBTrans.

set value2 to 1 for Chirpstack server, because Chirpstack will ignore same FCNT in re-transmission.

Example: AT+SETMAXNBTRANS=2,1

Set max NBTrans to 2, fcnt will increase +1 for each NBTrans

• Downlink: 0x33 02 01

  value1=0x02

          value2=0x01

2.6  Show Data in Datacake IoT Server

Step 3: Create an account or log in Datacake.

Step 4: Search the LSN50 and add DevEUI.

2.7  ​Firmware Change Log

2.8  Use VDD or +5V to Power External Sensor

1. VDD is 2.5~3.3v from the battery + diode, the VDD is always on, so when use VDD to power external sensor, make sure the sensor has a low power consumption in sleep mode ( less 50 uA) to get a long battery life.

2. +5V output is only ON when sampling. And MCU will turn off it after sampling. So if sensor can support 5v, +5V out is the best choice. See here for more info.

2.9  Battery & Power Consumption

LSN50v2 uses ER26500 + SPC1520 battery pack. See below link for detail information about the battery info and how to replace.

Battery Info & Power Consumption Analyze .

3.  Using the AT Commands

3.1  Access AT Commands

LSN50 supports AT Command set in the stock firmware. You can use a USB to TTL adapter to connect to LSN50 for using AT command, as below.

LSN50 v1 UART connection photo

LSN50 v2 UART connection photo

3.2  Common AT Command Sequence

3.2.1  Multi-channel ABP mode (Use with SX1301/LG308)

3.2.2  Single-channel ABP mode (Use with LG01/LG02)

See Sect 6.7

4.  Upload Firmware

Notes:

• Since image v1.3, the firmware will show version info during boot. If your device doesn't show version info, you may have a very old image version.
• Always run AT+FDR to reset parameters to factory default after an update image.
  If the update is from image >= v1.3 to another image version >=v1.3, then the keys will be kept after running AT+FDR.
  Otherwise (e.g. from v1.2 to v1.3), AT+FDR may erase the keys.

4.1  Upload Firmware via Serial Port

The LSN50's AT Command port can be used for firmware upgrade. The hardware connection for upgrade firmware is as below:

Step1: Download flash loader.

Step2: Download the LSN50 Image files.

Step3: Open flashloader; choose the correct COM port to update

4.2  Upload Firmware via ST-Link V2

You can use ST-LINK to upgrade firmware into LSN50. The hardware connection for upgrade firmware is as below:

Connection:

• ST-LINK v2 GND     <--> LSN50 GND
• ST-LINK v2 SWCLK <--> LSN50 PA14
• ST-LINK v2 SWDIO <--> LSN50 PA13
• ST-LINK v2 RST      <-->  LSN50 NRST

Step1: Install ST-LINK driver first and then install ST-LINK Utility

Step2: Download the LSN50 Image files.

Step3: Open ST-LINK utility, file --> open file to select the image to be upgraded. 

Step4: Click the “Program Verify” button on ST-LINK.

5.  Developer Guide

• Software Source Code Download : https://github.com/dragino/LoRa_STM32/tree/master/STM32CubeExpansion_LRWAN

• Hardware Source Code Download: https://github.com/dragino/Lora/tree/master/LSN50

• Software Source Code: https://github.com/dragino/LoRa_STM32/tree/master/STM32CubeExpansion_LRWAN 

• Hardware Design files:  https://github.com/dragino/Lora/tree/master/LSN50

• Compile instruction:     http://wiki.dragino.com/xwiki/bin/view/Main/Firmware%20Compile%20Instruction%20--%20STM32/

1. If you want to change frequency, modify the Preprocessor Symbols.

For example, change EU868 to US915

2. Compile and build

6.  FAQ

6.1  Why there is 433/868/915 version?

6.2  What is the frequency range of LT LoRa part?

Different LT version supports different frequency range, below is the table for the working frequency and recommend bands for each model:

6.3  How to change the LoRa Frequency Bands/Region?

You can follow the instructions for how to upgrade image.
When downloading the images, choose the required image file for download.

6.4  Can I use Private LoRa protocol?

LoRa Shield + UNO:

Use the LoRa Library and upload the LoRa Receive Sketch to Arduino.

Refs:  https://www.dropbox.com/sh/u9s41qdx5yujwcb/AAAT5r4QkMaeOogWrzJt7Wn4a?dl=0

Open the serial monitor to Arduino. The device acts as a LoRa Receiver and listen on the frequency 868.3Mhz by default.

LSN50:

Use the <LoRa RAW code> . The project file is in: MDK-ARM\STM32L072CZ-Nucleo\ Lora.uvprojx

Compile it and Upload it to LSN50, the LSN50 will transfer on the frequency 868.3Mhz.

In the Arduino Console, it will see the received packets as below.

6.5  How to set up LSN50 to work in 8 channel mode

• 903.9 - SF7BW125 to SF10BW125

• 904.1 - SF7BW125 to SF10BW125

• 904.3 - SF7BW125 to SF10BW125

• 904.5 - SF7BW125 to SF10BW125

• 904.7 - SF7BW125 to SF10BW125

• 904.9 - SF7BW125 to SF10BW125

• 905.1 - SF7BW125 to SF10BW125

• 905.3 - SF7BW125 to SF10BW125

• 904.6 - SF8BW500

6.6  How to set up LSN50 to work with Single Channel Gateway such as LG01/LG02?

6.7  How to configure the EUI keys in LSN50?

7.  Trouble Shooting

7.1  Connection problem when uploading firmware.

7.2  Why I can't join TTN V3 in US915 / AU915 bands?

It is due to channel mapping. Please see the Eight Channel Mode section above for details. 

7.3  AT Command input doesn't work

In the case if user can see the console output but can't type input to the device. Please check if you already include the ENTER while sending out the command. Some serial tool doesn't send ENTER while press the send key, user need to add ENTER in their string. 

8.  Order Info

Part Number: LSN50-XX-YY  or  LSN50v2-XX-YY-ZZ

XX: The default frequency band

• 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

YY: Hole Option

• 12: With M12 waterproof cable hole
• 16: With M16 waterproof cable hole
• 20: With M20 waterproof cable hole (LSN50 v2 doesn't have this version)
• NH: No Hole

ZZ: Battery Option ( Only valid for v2 model)

• 4: with 4000mAh battery
• 8: with 8500mAg battery

9. ​ Packing Info

For LSN50:

Package Includes:

• LSN50 LoRa Sensor Node x 1

Dimension and weight:

• Device Size: 8 x 6.5 x 5 cm
• Device Weight: 137g
• Package Size / pcs : 9 x 7 x 6cm
• Weight / pcs : 160g

For LSN50 v2:

Package Includes:

• LSN50v2 LoRa Sensor Node x 1
• External antenna x 1
• Spring Antenna (evaluate purpose)

Dimension and weight:

• Device Size: 9.7 x 6.5 x 4.7 cm
• Device Weight: 150g
• Package Size / pcs : 14.0 x 8x 5 cm
• Weight / pcs : 180g

10.  ​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.

11.  References

• Product Page 
• Data Sheet, Document Base
• Image Download