ISHTAR 1P-BLE User Manual


Thank you for choosing the ISHTAR 1P-BLE Bluetooth sensor node from DurUntash Lab. The ISHTAR 1P-BLE has a single sensor port combining digital and analog input signals. The sensor node can be used with all DurUntash Lab sensors. This online document will guide you through the most important features and specifications of the reader, and explains how to correctly operate it in a variety of applications. To understand how the ISHTAR 1P-BLE works, and to maximize its benefit, please make sure to read the contents of this user manual. We also recommend exploring the resources available on our website, and reading our blog articles





The ISHTAR 1P-BLE is a Bluetooth Low Energy-enabled sensor readout device and USB computer interface for DurUntash sensors. An ATSAMD21G18 ARM Cortex M0 processor is at the heart of the device motherboard. The Bluetooth LE module is an nRF51822 chipset from Nordic. An AP3602A chip provides just enough power (5 V @ 100 mA) to excite an external sensor connected to its port, and the ADS1115 16-bit analog to digital convertor is used to read the analog output from it. The firmware is written in C/C++ programming language and is fully compatible with Arduino boards that use the same ARM Cortex M0 processor (e.g.  Arduino Zero). A rechargeable Li-ion battery (3.7 V - 500 mAh) powers the ISHTAR 1P-BLE sensor node.


Included with the ISHTAR 1P-BLE is a micro-USB cable.

Side Panels

You can find a sensor port, an On/Off button and a micro-USB port  one on each side of the ISHTAR 1P-BLE. 

Sensor Port

The sensor port is a 3.5-mm 4-pole stereo plug connector. All DurUntash sensors come with the male version of the same connector. To connect a sensor to the ISHTAR 1P-BLE, simply plug it into the senor port. No need to press it too hard, but make sure that the connector tip is fully inserted in.


​USB Port

The micro-USB port is used for two purposes: 1) charging the node battery, and 2) communication with other devices (e.g. computer or Raspberry Pi). A micro-USB cable is provided with the product. The USB port has a protective cap that can be screwed on when not in use. With the cap on, the ISHTAR 1P-BLE will become fully weatherproof. 


On/Off Button

The ISHTAR 1P-BLE has a self-locking push button switch to turn the device on or off. Press the button to turn the device on (the head pops up). Press it again to turn the device off (the head locks in). The button has a built-in blue LED that flashes or stays on depending on the status of the device.

Handheld, Tabletop and Wall Mount Configurations

The ISHTAR 1P-BLE can be used as a handheld readout device. It also comes with all the required hardware accessories that allow it to be used in a tabletop configuration or two different wall-mount configurations as seen the pictures below. You will find the mounting hardware in a bag with the sensor node. Additional hardware (pole mounting brackets) is available upon order to mount the node securely to a pole. 

Wireless IoT Bluetooth sensor node & mobile app
Wireless IoT Bluetooth sensor node & mobile app



Wireless Communication

  • Bluetooth Module: nRF51822 chipset (Nordic)

  • Technology: Bluetooth Low Energy (BLE)

    • Note: ​BLE is available in Android v4.3 and later.

  • Range: Up to 7 m (22 ft)

Sensor Port

  • Number of Ports: 1

  • Port Type: 3.5-mm 4-pole stereo plug connector

  • Analog Input

    • Chip: ADS1115

    • Type: differential

    • Voltage Range: ±4.096 V

    • Resolution: 16 bit

  • Digital Input: 3.3 V logic level

  • Digital Output: 5.0 V pulse (external sensor power supply)


  • Enclosure Material: Polycarbonate; Weatherproof

    • Note: In the case of outdoor installation, we recommend placing the node inside an enclosure for protection.

  • Dimensions: 90 mm (L) x 80 mm (W) x 60 mm (H)

  • Operating Temperature Range: 5 to +50 °C

  • Operating Relative Humidity Range: 0 - 100%


  • Battery Type: 3.7 V - 500 mAh; rechargeable

  • Battery Life: ~500 hours per charge (more or less depending on sensor type and mode of use)

  • Charging Requirements: 100 mA @ 5.0 V (~5 h)

  • Solar Charger: compatible with standard USB solar chargers and power banks



Device Configuration

The ISHTAR 1P-BLE is ready to use out-of-the-box and almost no configurations ​are required. In this section, we will discuss possible configurations that can add to the fun of using the device. The ISHTAR 1P-BLE does not have a keypad, and therefore needs to rely on a software interface for changing device settings. New settings can be easily sent to the device using the SHUSHAN Mobile app, SHUSHAN CVI software, or the Arduino IDE. In the latter case, it is necessary to learn the easy-to-use ISHTAR 1P-BLE communication protocol and its command lines.

Connecting Sensors


The ISHTAR 1P-BLE automatically detects the type of DurUntash sensors connected to its port. Currently, the ISHTAR 1P-BLE firmware supports the APAS T1 soil moisture sensor, HITA E0 electrical conductivity sensor, and INSHU LWS leaf wetness sensor. By updating the firmware (whenever a new version is available), you will be able to read any sensor that is added to the DurUntash family.  

The ISHTAR 1P-BLE is programmed to take sensor measurements every 5 s when connected to the computer. In the Bluetooth mode, the node takes sensor measurements every 6 s, and checks the sensor port every 3 s if there no sensor is detected. There is a DS18B20 chip embedded in every DurUntash sensor with two bytes of on-board programmable ROM. Sensor-specific calibration coefficients (varies from one sensor to another) and single-byte sensor code ("100" for the APAS T1-1.8C sensor) are pre-programmed into these bytes. Every time before carrying out a measurement, the ISHTAR 1P-BLE attempts to read the memory of the DS18B20. This also allows the device to determine whether a sensor is present or not.


Connecting APAS T1 Soil Moisture Sensor

The APAS T1 sensor measures substrate water content and its temperature. Connect your APAS T1 sensor to the ISHTAR 1P-BLE by plugging it into its sensor port. The sensor is automatically detected by the ISHTAR 1P-BLE. By default, the APAS T1 soil moisture readings are in percent (%), and temperature in "°C". Please note that readings may be smaller than 0 % (negative) or greater than 100 %, which is normal.


The ISHTAR 1P-BLE has a built-in function that allows for comparing moisture measurements with upper (wet) and lower (dry) thresholds. If soil water content exceeds these thresholds, an irrigation signal is generated. This function is inactive by default.




Connecting HITA E0 Electrical Conductivity Sensor

The HITA E0 sensor measures the electrical conductivity of the substrate (bulk EC) or solution, and its temperature. Connect your HITA E0 sensor to the ISHTAR 1P-BLE by plugging it into its sensor port. The sensor is automatically detected by the datalogger. By default, electrical conductivity readings are recorded in "dS/m", total dissolved solids (TDS) in "ppm" and temperature in "°C".

Note: 1 mho/m = 1 mmho/cm = 1 mS/cm = 1 dS/m = 1000 µS/cm


Connecting INSHU Leaf Wetness Sensor (LWS)


The INSHU LWS sensor measures surface wetness (presence of water as a result of rainfall, dew, or snow) and temperature. The INSHU LWS works great with our SHINAK datalogger series, however you may use the ISHTAR 1P-BLE to check if the sensor is functional. Connect your INSHU LWS sensor to the ISHTAR 1P-BLE by plugging it into its sensor port. The sensor is automatically detected by the device. The INSHU sensor data look exactly like the APAS T1 soil moisture sensor.


Switching Between Sensors


There are scenarios in which you might need to switch between different soil moisture sensors or EC sensors, or connect both to the same device. A good example is when you need to take spot measurements using several sensors and a single handheld reader. DurUntash readout devices automatically detect sensors that are connected to their port(s). However, there is always a delay of up to 10 seconds after discounting a sensor during which the readout device remains locked to the previous sensor, and therefore cannot detect a new sensor. To make sure you device has enough time to switch from one sensor to another, always wait for at least 10 seconds before connecting a new sensor. 


Signal Conditioning


All DurUntash Lab readout devices and data acquisition hardware contain a signal processing and filtering algorithm that ensures only “good” data make it to the user. One of the filtering stages checks for sudden spikes in sensor measurements. Any given measurement that is not persistent is assumed to be a noise and therefore removed. This might appear as a lag time and you’ll notice it when you touch the sensor or irrigate (readings take time to change).  


Taking Sensor Readings via Smartphone

Bluetooth Low Energy (BLE)

The version of Bluetooth supported by the node is Low Energy (BLE).  Bluetooth Low Energy is the ultra-low power version of Bluetooth meant for low-cost, low-power sensor and IoT applications, in which continuous connection is not required, but long battery life is a priority. 


Taking everything into consideration, you will need a smartphone with Android v5.0 and later. Communication using Classic Bluetooth is not supported by the ISHTAR node.

SHUSHAN Mobile App

The ISHTAR 1P-BLE is designed to work with both smartphones and computers. You can use the SHUSHAN Mobile app for Android to connect to the the ISHTAR Bluetooth node. The SHUSHAN Mobile app can be used for easy configuration, sensor calibration, data retrieval, and even mobile-based data logging.


The SHUSHAN Mobile can collect sensor readings from multiple ISHTAR Bluetooth nodes and log geo-tagged timestamped data  manually or automatically on smartphone (mobile-based data logging). Every ISHTAR 1P-BLE node has a name (alias) that is transmitted to your phone. You can modify this name and use it to identify specific node. 


The app is provided free of charge with all compatible DurUntash Lab products. Please refer to the SHUSHAN Mobile user manual to learn more about the app.  


Connect to Computer


The ISHTAR 1P-BLE has a timeout function that disables its USB port (and stops sending data) if no computer connection is present within 60 s from powering the device up. This allows the device to save power and enter into Bluetooth mode. Turn the device on/off to reset the timer. You can connect the ISHTAR 1P-BLE to the computer using the micro-USB cable included.


The SHUSHAN CVI is Windows®-based (7, 8 or 10) graphical user interface, which can be used for data visualization, device/sensor configuration, firmware updates, and real-time data logging and monitoring. The SHUSHAN CVI is free and you can download its latest version from our website. A USB driver must be installed (in most cases, it is automatically installed) before connecting the ISHTAR 1P-BLE USB cable to the computer. 

The SHUSHAN CVI is designed to work with all DurUntash products (e.g. reader, data logger, sensor interface). Thus, some features of the software might not be available when connected to the ISHTAR 1P-BLE. Please refer to the SHUSHAN CVI page for more information about the software. Contact us if you had any troubles with the installation.

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Connect to Raspberry Pi

Connecting the ISHTAR 1P-BLE to the Raspberry Pi (any model) is very easy and straightforward. Simply use the included micro-USB cable and connect the datalogger to a Raspberry Pi USB port. The ISHTAR 1P-BLE will appear as a USB device on the Pi. The number of nodes that can be connected to a Raspberry Pi board depends on its model. For example, up to eight sensor nodes can be simultaneously connected to the Raspberry Pi 3B+. 

Port Settings

The required COM port settings to establish a connection with the ISHTAR 1P-BLE are as the following:

  • Baud Rate = N/A

  • Parity = N/A

  • Data Bits = N/A

  • Stop Bits = N/A

  • DTR Enable = True


Please note that unlike most Arduino boards (e.g. Arduino Uno), the Data Terminal Ready (DTR) is enabled here. Please continue reading to learn how to communicate with the ISHTAR 1P-BLE using simple command lines from your own custom-designed software.


Communication Protocol


The ISHTAR 1P-BLE takes care of the math required to apply sensor calibration coefficients, calculate EC / TDS, temperature compensation, etc. So in most cases it would be easier to use the ISHTAR 1P-BLE as an interface between DurUntash sensors and your application running on PC or the Raspberry Pi, or even an Arduino board. The ISHTAR 1P-BLE can also be connected to third-party data acquisition systems with a serial (must be converted to USB) or USB port.


We have developed a simple-to-use communication protocol and a number of commands to make this possible. These commands are listed in the link below:

List of Commands

Please contact us for more information if you are interested in integrating our sensors or readout devices into your monitoring system.

Command String Format​

Each string of command is sent as human-readable ASCII text followed by a carriage return character (ASCII 13, or '\r') and a newline character (ASCII 10, or '\n'). The general command format is as the following:

<[device code], [device number],[primary command number],[secondary command number / variable],[variable],[variable],[variable], [variable],

Here's what the terms in the command string mean:

  1. Device code for the ISHTAR 1P-BLE is "207" (read-only).

  2. Device number can be set to a number between 0 - 255 (0 or 255 by default).

  3. Primary command number determines what action needs to be taken by the device.

  4. Secondary command number works like the primary command number and determines what sub-action needs to be taken by the system. SCN is rarely used.

  5. Variable specifies new values or new settings to be sent to the device. A variable is always positive.

Data String Format​

To receive sensor readings from the ISHTAR 1P-BLE, no command is required. The node is programmed to make strings of data available on its USB port every 10 s (if a connection is established with the computer or other devices). A series of commands can also be used to configure the device and change the default settings. Right after a sensor is connected to the node, sensor's (if connected) read-only 64-bit digital ID (also called "serial number" here) is read and reported to the user in a separate string. 

Five series of numbers are embedded in every string that is sent via the serial port: 1) device code, 2) device number, 3) sensor channel name (if connected), 4) sensor ID (if connected), and 5) sensor code (if connected). The combination of these unique numbers creates a unique digital ID that could be used to identify specific device and sensor on the network.


Each string of data is printed to the serial port as human-readable ASCII text followed by a carriage return character (ASCII 13, or '\r') and a newline character (ASCII 10, or '\n'). The general sensor data format (same for all DurUntash products) is as the following:

>[device code], [device number],[sensor channel code],[primary sensor reading],[temperature],[battery voltage],[measurement unit], [secondary sensor reading],[sensor ID],[sensor code]

Here's what the terms in the data string mean if sent by the ISHTAR 1P-BLE:

  1. Device code is "207" (read-only).

  2. Device number can be set to a number between 0 - 255 (0 or 255 by default).

  3. Sensor channel code varies depending on the sensor type and number of sensor channels on the device. The ISHTAR 1P-BLE has one sensor channel, therefore sensor type is the only determining factor. The channel code for DurUntash sensors are as the following:

    • APAS T1-1.8C: 10 

    • APAS T1-4.5C: 300 

    • APAS T1-3.0C: 350 

    • HITA E0: 1000 

    • INSHU LWS: 400

    • No sensor connected: 100 

  4. Primary sensor reading depends on sensor type. Every reading is reported in its corresponding unit (% or dS/m) plus a constant value of 1000 (primary sensor reading = original value + 1000), which must be subtracted from the reading to obtain the correct value. For example, a soil moisture reading of 55 % would appear as 1055 (= 1000 + 55) on the serial port.

  5. Temperature is reported in degree Celsius (°C; default) or degree Fahrenheit (°F) depending on the settings, plus a constant value of 273. For example, a temperature of 25 °C is sent as 298 (= 273 + 25).

  6. Battery voltage is in volts (V).

  7. Measurement unit is "0" (default) or "1". A value of "0" means the temperature measurement unit is Metric and "1" means it is English.

  8. Secondary sensor reading depends on sensor type. For the APAS T1 soil moisture sensor and INSHU LWS, the secondary reading is raw soil moisture measurements or surface wetness from ADC after temperature compensation (no unit). For the HITA E0 electrical conductivity sensor, the secondary measurement is TDS in ppm.

  9. Sensor ID is unique to sensor.

  10. Sensor code is used to identify the type of sensor connected. It is defined as the following for different sensor types:

    • APAS T1-4.5C: 99

    • APAS T1-3.0C: 104

    • APAS T1-1.8C: 100

    • HITA E0: 101

    • INSHU LWS: 103


For example, a general string of data sent by the Bluetooth node when different sensors are connected will look like the following:

APAS T1-1.8C:



where soil moisture is calculated as 1088.00 - 1000 = 88.00 %, and the corresponding raw reading (temperature compensated) is 8513 (no unit).




where electrical conductivity is calculated as 1000.52 - 1000 = 0.52 dS/m, and TDS is 483 ppm.




where leaf wetness is calculated as 1010.00 - 1000 = 10.00 %, and the corresponding raw reading (temperature compensated) is 5222 (no unit).

If no sensor is connected, the string will look like the following (only battery voltage is reported):


Recharging the Battery

The ISHTAR 1P-BLE is equipped with a rechargeable Li-ion battery (3.7 V - 500 mAh) that can power the unit for several weeks. Any standard charger providing 5.0 V with a micro-USB cable type B (cable included) can be used to recharge the battery.  The ISHTAR 1P-BLE has a built-in charger on its motherboard that limits the current to 100 mA. It takes about 5 hours to fully recharge the battery at this rate with the device being turned off. Leaving the device turned on (not recommended) while charging might add significant number of hours to this time. This opens the door for a variety of options: 1) using computer/laptop USB port as charger, 2) USB wall charger, 3) USB power bank, or 3) solar charger. The first option is the most convenient and widely available. Any device with a USB port (type A) can do the job and it is not limited to computers. The other two options are explained below.

USB Wall Charger


USB wall chargers are widely used for charging mobile phones, tablets, etc. The same type of charger can be used for recharging the node's battery provided it has a micro-USB cable or hosts a USB port type A. Use the provided micro-USB cable to connect the device to your wall charger. 

Solar Charger

As an option, we offer a mini solar panel with micro USB cable to plug into the reader and recharge the battery whenever there is a light source. The solar charger provides much more juice than the node consumes at its peak of power usage, so the its battery stays fully charged all the time.

Alternatively, a regular USB power bank or a solar powered USB bank can recharge the battery while being used. If you are not sure of the compatibility of what you have we the ISHTAR 1P-BLE sensor node, please feel free to discuss your options with us.



Update Firmware

Currently, the SHUSHAN CVI-Wireless application supports the ISHTAR 1P-BLE firmware update. The ISHTAR 1P-BLE firmware is Arduino-compatible (written in standard Arduino-compatible C/C++ language) meaning that the Arduino IDE or Visual Studio Code  can also be used to upload a new firmware into the ISHTAR 1P-B.  

Retrieve Device Information

Please take the following steps to retrieve the device information using the SHUSHAN CVI software:  


  1. Please read this section first.

  2. Connect the ISHTAR 1P-BLE to the computer.

  3. Open the SHUSHAN CVI software.

  4. Go to the Help menu and click on "Device Information". A dialog should appear with a list of device information (name, manufacturer, product URL, firmware version, compilation date, and serial number). 

  5. Click Ok and you will be redirected to the product page on our website.



Under normal conditions, the ISHTAR 1P-BLE sensor node is maintenance-free. If your device needs maintenance with respect to its performance, please feel free to return it to us. We will conduct a thorough inspection of the device, and carry out any repairs or part replacements that are necessary. Any costs arisen from this service that is not covered by the warranty is the responsibility of the customer. This includes the cost of shipping, labor and any new parts used in the repair. Please see our terms and conditions page for more information.


Table below has summarized the most common issues that you might experience with the device and some possible fixes. If a problem persists or is not listed here, feel free to contact us.

Possible Reason and Fix


Measurement data show as 999

This is an error code. When there is a temperature measurement error, both temperature and sensor reading (e.g. water content) are reported as 999.

SHUSHAN CVI cannot connect to ISHTAR 1P-BLE

This could be a hardware or software issue. Check the following to troubleshoot:

  • Make sure that the correct device name and port are selected.

  • Check the battery level. Make sure the device is charged.

  • Check the micro-USB cable. Make sure it is securely connected to both computer (or other devices) and the datalogger.

  • Make sure the USB driver is installed. The computer must recognize the device as soon as connected.

SHUSHAN CVI loses connection with ISHTAR 1P-BLE

This might be hardware issue. Replace the micro-USB cable.

Incorrect sensor readings

If you recently updated the settings or uploaded new calibration coefficients, make sure the coefficients are correct. Please refer to the sensor user manual for more information about the calibration process.