Table of Contents:

1.  Introduction

1.1 ​ What is NSPH01 Soil pH Sensor

The Dragino NSPH01 is a NB-IoT soil pH sensor for IoT of Agriculture. It is designed to measure the soil pH and soil temperature, so to send to the platform to analyze the soil acid or alkali level. The probe is IP68 waterproof.

NSPH01 probe is made by Solid AgCl reference electrode and Pure metal pH sensitive electrode. It can detect soil's pH with high accuracy and stable value. The NSPH01 probe can be buried into soil for long time use.

NarrowBand-Internet of Things (NB-IoT) is a standards-based low power wide area (LPWA) technology developed to enable a wide range of new IoT devices and services. NB-IoT significantly improves the power consumption of user devices, system capacity and spectrum efficiency, especially in deep coverage.

NSPH01 supports different uplink methods include TCP,MQTT,UDP and CoAP  for different application requirement.

NSPH01 is powered by 8500mAh Li-SOCI2 battery, It is designed for long term use up to 5 years. (Actually Battery life depends on the use environment, update period & uplink method)

To use NSPH01, user needs to check if there is NB-IoT coverage in the installation area and with the bands NSPH01 supports. If the local operator supports it, user needs to get a NB-IoT SIM card from local operator and install NSPH01 to get NB-IoT network connection.



1.2  Features

  • NB-IoT Bands: B1/B3/B8/B5/B20/B28 @H-FDD
  • Monitor soil pH with temperature compensation.
  • Monitor soil temperature
  • pH and Temperature alarm function
  • Monitor Battery Level
  • Support pH calibration by end user
  • Uplink on periodically
  • Downlink to change configure
  • IP66 Waterproof Enclosure
  • IP68 rate for the Sensor Probe
  • Ultra-Low Power consumption
  • AT Commands to change parameters
  • Micro SIM card slot
  • 8500mAh Battery for long term use

1.3  Specification

Common DC Characteristics:

  • Supply Voltage: 2.1v ~ 3.6v
  • Operating Temperature: -40 ~ 85°C

NB-IoT Spec:

  • B1 @H-FDD: 2100MHz
  • B3 @H-FDD: 1800MHz
  • B8 @H-FDD: 900MHz
  • B5 @H-FDD: 850MHz
  • B20 @H-FDD: 800MHz
  • B28 @H-FDD: 700MHz

1.4  Probe Specification

Soil pH:

  • Range: 3 ~ 10 pH 
  • Resolution: 0.01 pH
  • Accuracy: ±2% under (0~50 ℃, Accuracy will poor under 0 due to frozen)
  • Temperature Compensation Range: 0 ~ 50℃
  • IP68 Protection
  • Length: 3.5 meters

Soil Temperature:

  • Range -40℃~85℃
  • Resolution: 0.1℃
  • Accuracy: <±0.5℃(-10℃~40℃),<±0.8℃ (others)
  • IP68 Protection
  • Length: 3.5 meters

1.5  ​Applications

  • Smart Agriculture

1.6  Pin mapping and power on


2.  Use NSPH01 to communicate with IoT Server

2.1  How it works

The NSPH01 is equipped with a NB-IoT module, the pre-loaded firmware in NSPH01 will get environment data from sensors and send the value to local NB-IoT network via the NB-IoT module.  The NB-IoT network will forward this value to IoT server via the protocol defined by NSPH01.

The diagram below shows the working flow in default firmware of NSPH01:


2.2 ​ Configure the NSPH01

2.2.1  Test Requirement

To use NSPH01 in the field, make sure meet below requirements:

  • Your local operator has already distributed a NB-IoT Network there.
  • The local NB-IoT network used the band that NSPH01 supports.
  • Your operator is able to distribute the data received in their NB-IoT network to your IoT server.

Below figure shows our testing structure. Here we have NB-IoT network coverage by China Mobile, the band they use is B8.  The NSPH01 will use CoAP( or raw UDP( or MQTT( TCP( to send data to the test server.


2.2.2  Insert SIM card

User need to take out the NB-IoT module and insert the SIM card like below. ( Pay attention to the direction)


2.2.3  Connect USB – TTL to NSPH01 to configure it

User need to configure NSPH01 via serial port to set the Server Address / Uplink Topic to define where and how-to uplink packets. NSPH01 support AT Commands, user can use a USB to TTL adapter to connect to NSPH01 and use AT Commands to configure it, as below.


  USB TTL GND <---->  GND



In the PC, use below serial tool settings:

  • Baud:              9600
  • Data bits:        8
  • Stop bits:        1
  • Parity:             None
  • Flow Control: None

Make sure the switch is in FLASH position, then power on device by connecting the jumper on NSPH01. NSPH01 will output system info once power on as below, we can enter the password: 12345678 to access AT Command input.


Note: the valid AT Commands can be found at:  https://www.dropbox.com/sh/351dwor6joz8nwh/AADn1BQaAAxLF_QMyU8NkW47a?dl=0

2.2.4  Use CoAP protocol to uplink data

Note: if you don't have CoAP server, you can refer this link to set up one: http://wiki.dragino.com/xwiki/bin/view/Main/Set%20up%20CoAP%20Server/

Use below commands:

  • AT+PRO=1                                               //  Set to use CoAP protocol to uplink
  • AT+SERVADDR=,5683      //   to set CoAP server address and port
  • AT+URI=5,11,"mqtt",11,"coap",12,"0",15,"c=text1",23,"0"        //  Set COAP resource path

For parameter description, please refer to AT command set


After configure the server address and reset the device (via AT+ATZ ), NSPH01 will start to uplink sensor values to CoAP server.


2.2.5  Use UDP protocol to uplink data(Default protocol)

This feature is supported since firmware version v1.0.1

  • AT+PRO=2                                               //  Set to use UDP protocol to uplink
  • AT+SERVADDR=,5601      //   to set UDP server address and port
  • AT+CFM=1                                             //    If the server does not respond, this command is unnecessar



2.2.6  Use MQTT protocol to uplink data

This feature is supported since firmware version v110

  • AT+PRO=3                                                 // Set to use MQTT protocol to uplink
  • AT+SERVADDR=,1883         // Set MQTT server address and port
  • AT+CLIENT=CLIENT                                  // Set up the CLIENT of MQTT
  • AT+UNAME=UNAME                               // Set the username of MQTT
  • AT+PWD=PWD                                        // Set the password of MQTT
  • AT+PUBTOPIC=NSE01_PUB                    // Set the sending topic of MQTT
  • AT+SUBTOPIC=NSE01_SUB                    // Set the subscription topic of MQTT



MQTT protocol has a much higher power consumption compare vs UDP / CoAP protocol. Please check the power analyze document and adjust the uplink period to a suitable interval.

2.2.7  Use TCP protocol to uplink data

This feature is supported since firmware version v110

  • AT+PRO=4                                              // Set to use TCP protocol to uplink
  • AT+SERVADDR=,5600      // to set TCP server address and port



2.2.8  Change Update Interval

Users can use the below command to change the uplink interval.

  • AT+TDC=7200        // Set Update Interval to 7200s (2 hour)

NOTE: By default, the device will send an uplink message every 2 hours. Each Uplink Include 8 set of records in this 2 hour (15 minute interval / record).

2.3  Uplink Payload

In this mode, uplink payload includes 87 bytes in total by default.

Each time the device uploads a data package, 8 sets of recorded data will be attached. Up to 32 sets of recorded data can be uploaded.

ValueDevice IDVerBATSignal StrengthMODInterruptSoil PHSoil TemperatureTime stampSoil TemperatureSoil PHTime stamp  .....

If we use the MQTT client to subscribe to this MQTT topic, we can see the following information when the NSPH01 uplink data.


The payload is ASCII string, representative same HEX:


0x f868411056754138  0064  0c78  17  01  00  0225   010b  6315537b  010b0226631550fb  010e022663154d77  01110225631549f1  011502246315466b  01190223631542e5  011d022163153f62  011e022163153bde 011e022163153859



  • Device ID: 0xf868411056754138 = f868411056754138 
  • Version:    0x0064=100=1.0.0 
  • BAT:     0x0c78 = 3192 mV = 3.192V 
  • Singal: 0x17 = 23 
  • Mod:   0x01 = 1 
  • Interrupt: 0x00= 0
  • Soil PH:    0x0225= 549 = 5.49
  • Soil Temperature: 0x010b =267=26.7 °C
  • Soil Temperature,Soil PH,Time stamp :  010b0226631550fb
  • 8 sets of recorded data: Temperature,Soil PH,Time stamp :  010e022663154d77,.......

2.4  Payload Explanation and Sensor Interface

2.4.1  Device ID

By default, the Device ID equal to the last 15 bits of IMEI.

User can use AT+DEUI to set Device ID



The Device ID is stored in a none-erase area, Upgrade the firmware or run AT+FDR won't erase Device ID.

2.4.2  Version Info

Specify the software version: 0x64=100, means firmware version 1.00.

For example: 0x00 64 : this device is NSPH01 with firmware version 1.0.0.

2.4.3  Battery Info

Check the battery voltage for NSPH01.

Ex1: 0x0B45 = 2885mV

Ex2: 0x0B49 = 2889mV

2.4.4  Signal Strength

NB-IoT Network signal Strength.

Ex1: 0x1d = 29

0        -113dBm or less

1        -111dBm

2...30 -109dBm... -53dBm

31      -51dBm or greater

99      Not known or not detectable

2.4.5  Soil PH

Get the PH content of the soil. The value range of the register is 300-1000(Decimal), divide this value by 100 to get the percentage of PH in the soil.

For example, if the data you get from the register is 0x05 0xDC, the PH content in the soil is

0229(H) = 549(D) /100 = 5.49.

2.4.6  Soil Temperature

Get the temperature in the soil. The value range of the register is -4000 - +800(Decimal), divide this value by 100 to get the temperature in the soil. For example, if the data you get from the register is 0x09 0xEC, the temperature content in the soil is


If payload is 0105H: ((0x0105 & 0x8000)>>15 === 0),temp = 0105(H)/10 = 26.1 °C

If payload is FF7EH: ((FF7E & 0x8000)>>15 ===1),temp = (FF7E(H)-FFFF(H))/10 = -12.9 °C

2.4.7  Timestamp

Time stamp : 0x6315537b =1662342011

Convert Unix timestamp to time 2022-9-5 9:40:11.

2.4.8  Digital Interrupt

Digital Interrupt refers to pin GPIO_EXTI, and there are different trigger methods. When there is a trigger, the NSPH01 will send a packet to the server.

The command is:

AT+INTMOD=3    //(more info about INMOD please refer AT Command Manual).

The lower four bits of this data field shows if this packet is generated by interrupt or not. Click here for the hardware and software set up.


0x(00): Normal uplink packet.

0x(01): Interrupt Uplink Packet.

2.4.9  ​+5V Output

NSPH01 will enable +5V output before all sampling and disable the +5v after all sampling.  

The 5V output time can be controlled by AT Command.


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

2.5  Downlink Payload

By default, NSPH01 prints the downlink payload to console port.

Downlink Control TypeFPortType CodeDownlink payload size(bytes)
TDC (Transmit Time Interval)Any014


  •  Set TDC

If the payload=0100003C, it means set the END Node's TDC to 0x00003C=60(S), while type code is 01.

Payload:    01 00 00 1E    TDC=30S

Payload:    01 00 00 3C    TDC=60S

  •  Reset

If payload = 0x04FF, it will reset the NSPH01


Downlink Payload: 06000003, Set AT+INTMOD=3

2.6  ​LED Indicator

The NSPH01 has an internal LED which is to show the status of different state. 

  • When power on, NSPH01 will detect if sensor probe is connected, if probe detected, LED will blink four times. (no blinks in this step is no probe)
  • Then the LED will be on for 1 second means device is boot normally.
  • After NSPH01 join NB-IoT network. The LED will be ON for 3 seconds.
  • For each uplink probe, LED will be on for 500ms.

2.7  Installation and Maintain

2.7.1  Before measurement

If the NSPH01 has more than 7 days not use or just clean the pH probe. User should put the probe inside pure water for more than 24 hours for activation. If no put in water, user need to put inside soil for more than 24 hours to ensure the measurement accuracy.  

2.7.2  Measurement

Measurement the soil surface:

image-20220907154700-18.png ​

Choose the proper measuring position. Split the surface soil according to the measured deep.

Put pure water, or rainwater to make the soil of measurement point to moist mud. Remove rocks or hard things.

Slowly insert the probe to the measure point. Don't use large force which will break the probe. Make sure not shake when inserting.

Put soil over the probe after insert. And start to measure.

Measurement inside soil:

Dig a hole with diameter > 20CM.

Insert the probe inside, method like measure the surface.

2.7.3  Maintain Probe

  1. pH probe electrode is fragile and no strong. User must avoid strong force or hitting it.
  2. After long time use (3~ 6  months). The probe electrode needs to be clean; user can use high grade sandpaper to polish it or put in 5% hydrochloric acid for several minutes. After the metal probe looks like new, user can use pure water to wash it.
  3. Probe reference electrode is also no strong, need to avoid strong force or hitting.
  4. User should keep reference electrode wet while not use.
  5. Avoid the probes to touch oily matter. Which will cause issue in accuracy.
  6. The probe is IP68 can be put in water.

2.8  PH and Temperature alarm function

➢ AT Command:

AT+ PHALARM=min,max

² When min=3, and max≠0, Alarm higher than max

² When min≠0, and max=0, Alarm lower than min

² When min≠0 and max≠0, Alarm higher than max or lower than min


AT+ PHALARM =5,8       // Alarm when PH lower than 5.


² When min=0, and max≠0, Alarm higher than max

² When min≠0, and max=0, Alarm lower than min

² When min≠0 and max≠0, Alarm higher than max or lower than min


AT+ TEMPALARM=20,30     // Alarm when temperature lower than 20.

2.9  Set the number of data to be uploaded and the recording time

➢ AT Command:

  • AT+TR=900           //  The unit is seconds, and the default is to record data once every 900 seconds.( The minimum can be set to 180 seconds)
  • AT+NOUD=8       //    The device uploads 8 sets of recorded data by default. Up to 32 sets of record data can be uploaded.

 The diagram below explains the relationship between TR, NOUD, and TDC more clearly:


2.10  Read or Clear cached data

➢ AT Command:

  • AT+CDP          //  Read cached data
  • AT+CDP=0     //  Clear cached data


2.11  Calibration

User can do calibration for the probe. It is limited to use below pH buffer solution to calibrate: 4.00, 6.86, 9.18. When calibration, user need to clean the electrode and put the probe in the pH buffer solution to wait the value stable ( a new clean electrode might need max 24 hours to be stable).

After stable, user can use below command to calibrate.

pH buffer solutionAT Command to calibrateDownlink CommandRead Cal Value

0x13 04
Reply with Calibrate payload

Example 41,61,91


0x13 06
Reply with Calibrate payload


0x13 09
Reply with Calibrate payload

Factory DefaultAT+PHCAL=15

0x13 15
Reply with Calibrate payload

Example 151


2.12  ​Firmware Change Log

Download URL & Firmware Change log: https://www.dropbox.com/sh/1tv07fro2pvjqj8/AAD-2wbfGfluTZfh38fQqdA_a?dl=0

Upgrade Instruction: Upgrade Firmware

2.13 Battery & Power Consumption

NSPH01 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. ​ Access NB-IoT Module

Users can directly access the AT command set of the NB-IoT module.

The AT Command set can refer the BC35-G NB-IoT Module AT Command: https://www.dragino.com/downloads/index.php?dir=datasheet/other_vendors/BC35-G/  


4.  Using the AT Commands

4.1  Access AT Commands

See this link for detail:  https://www.dropbox.com/sh/351dwor6joz8nwh/AADn1BQaAAxLF_QMyU8NkW47a?dl=0

AT+<CMD>?                    : Help on <CMD>

AT+<CMD>                      : Run <CMD>

AT+<CMD>=<value>      : Set the value

AT+<CMD>=?                  : Get the value

General Commands       

AT                            : Attention        

AT?                           : Short Help      

ATZ                          : MCU Reset     

AT+TDC                   : Application Data Transmission Interval

AT+CFG                   : Print all configurations

AT+CFGMOD           : Working mode selection

AT+INTMOD            : Set the trigger interrupt mode

AT+5VT                     : Set extend the time of 5V power   

AT+PRO                    : Choose agreement

AT+RXDL                   : Extend the sending and receiving time

AT+SERVADDR          : Server Address

AT+TR      : Get or Set record time"

AT+APN            : Get or set the APN

AT+FBAND          : Get or Set whether to automatically modify the frequency band

AT+DNSCFG         :  Get or Set DNS Server

AT+GETSENSORVALUE   : Returns the current sensor measurement

AT+NOUD      : Get or Set the number of data to be uploaded

AT+CDP     : Read or Clear cached data

AT+TEMPALARM      : Get or Set alarm of temp

AT+PHALARM     : Get or Set alarm of PH

AT+ PHCAL   : calibrate PH value

COAP Management       

AT+URI            : Resource parameters

UDP Management

AT+CFM          : Upload confirmation mode (only valid for UDP)

MQTT Management

AT+CLIENT               : Get or Set MQTT client

AT+UNAME             : Get or Set MQTT Username

AT+PWD                  : Get or Set MQTT password

AT+PUBTOPIC          : Get or Set MQTT publish topic

AT+SUBTOPIC          : Get or Set MQTT subscription topic


AT+FDR              : Factory Data Reset

AT+PWORD       : Serial Access Password

​5.  FAQ

5.1 ​ How to Upgrade Firmware

User can upgrade the firmware for 1) bug fix, 2) new feature release.

Please see this link for how to upgrade:  http://wiki.dragino.com/xwiki/bin/view/Main/Firmware%20Upgrade%20Instruction%20for%20STM32%20base%20products/#H2.HardwareUpgradeMethodSupportList

Notice, NSPH01 and LSPH01 share the same mother board. They use the same connection and method to update.

5.2  Can I calibrate NSPH01 to different soil types?

NSPH01 is calibrated for saline-alkali soil and loamy soil. If users want to use it for other soil, they can calibrate the value in the IoT platform base on the value measured by saline-alkali soil and loamy soil. The formula can be found at this link.

6.  Trouble Shooting

6.1  ​Connection problem when uploading firmware

Please see: http://wiki.dragino.com/xwiki/bin/view/Main/Firmware%20Upgrade%20Instruction%20for%20STM32%20base%20products/#H3.3Troubleshooting

6.2  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. 

6.3  Not able to connect to NB-IoT network and keep showing "Signal Strength:99".

This means sensor is trying to join the NB-IoT network but fail. Please see this link for trouble shooting for signal strenght:99.

7. ​ Order Info

Part Number: NSPH01

8.  Packing Info

Package Includes:

  • NSPH01 NB-IoT pH Sensor x 1
  • External antenna x 1

Dimension and weight:

  • Device Size: cm
  • Device Weight: g
  • Package Size / pcs : cm
  • Weight / pcs : g

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

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