WAVESHARE SX1262 LoRa Modules Instruction Manual

WAVESHARE SX1262 LoRa Modules Instruction Manual

Overview

Introduction

This series of products are LoRa modules using the new generation of SX1262 RF chip, with the features of long communication distance and strong anti-interference ability. Suitable for Sub- GHz frequency band networks, and is available in LF (410~510MHz) or HF (850~930MHz) frequency band versions. Combined with a LoRa gateway, it can be connected to servers such as TTN to build a LoRaWAN network. In addition to the basic LoRaWAN version, it also provides an optional GNSS positioning function with GPS/BD support.

Features

Common features:
Standard Raspberry Pi 40PIN GPIO header, supports Raspberry Pi series boards.
The new generation SX1262 has higher power efficiency and longer transmission distance than the SX1278.
Suitable for the Sub-GHz band, combined with LoRa gateway, can be quickly connected to a cloud server such as TTN to build a LoRaWAN network.
GNSS version features:
Onboard L76K module with GPS/BD support, provides accurate clock and location info for node module.
Onboard battery holder ,supports ML1220 rechargeable battery, for power off preserving information and hot starts.
Onboard 4 LED indicators for module operating status.
Comes with online development resources and manual(example in C)

Parameters

Hardware Description

Hardware Selection

Hardware Connection

Pinout Definition

CS MOSI MISO CLK is the SPI interface of SX1262, and BUSY is the status pin of SX1262. Use MCU’s SPI bus to communicate with SX1262 XXXM LoRaWAN/GNSS HAT. When MCU reads and writes SX1262 registers, it needs to read and write parameters in the order of Opcode + Address + Data. For more information, please refer to chapters 8, 10, 11, and 12 of the datasheet When the MCU reads and writes the SX1262 register, it needs to detect the BUSY pin first. The low level indicates that it is idle and can be read and written normally, and the high level indicates that it is busy and cannot read and write the register, as shown in the figure below.

RESET is the factory reset pin of SX1262, pull it low for 100us to restore the default parameters of the register, and keep a high level when working.
RXEN, TXEN are RF single-pole switch (SPDT
TXEN pin is connected to BCM(6), and RXEN pin is not used, which is -1 by default. Refer to the schmatic diagram
DIO1, DIO2, and DIO3 are SX1262 functional GPIO pins, which can be set as input and output to indicate various states of SX1262 (8.5 IRQ Handling in the figure below), usually, DIO1 is set as an interrupt output in the state shown in the figure below, and DIO2 is connected to RXEN and set as the control pin of the RF single-pole switch, DIO3 is set to supply power to the TCXO, for details, please refer to Datasheet 8.3.2, 8.5 summary.

Dimensions

Lora Beginner Test

If you are not familiar with Linux (or Raspberry Pi), please refer to the Raspberry Pi Documentation to set up the Raspberry Pi to turn on the SPI bus, etc., as shown in the following figure:

Demo Download

Open the Raspberry Pi terminal, and enter the “root” mode. Use the following commands to download sample demo and unzip:

sudo su

wget https://files.waveshare.com/wiki/SX1262-XXXM-LoRaWAN-GNSS-HAT/Sx126x_lorawan_hat_code.zip

unzip Sx126x_lorawan_hat_code.zip

cd cd sx126x_lorawan_hat_code/python/lora/

python3 setup.py install # If you need “sudo” privileges, add “sudo” in front of python 3, and be sure to install the libraries the first time you download the demo

cd example/SX126x/

python3 transmission.py # This sample demo requires two SX1262 XXXM LoRaWA N/GNSS HAT for send/receive tests, this command is for the transmitter module

python3 receiver_continuous.py # This sample demo requires two SX1262 XXXM Lo RaWAN/GNSS HAT transceiver tests, this command is for the receiver module

sx126x_lorawan_hat_code/python/lora/examples/network, under the directory example demo for a single-channel gateway and node

cd sx126x_lorawan_hat_code/python/lora/examples/network

python3 LoRa_simple_node.py # This sample demo requires two SX1262 XXXM Lo RaWAN/GNSS HAT for send/receive tests, this command is for the node module

python3 LoRa_simple_gateway.py # This sample demo requires two SX1262 XXXM LoRaWAN/GNSS HAT for send/receive tests, this command is for the single-channel gateway module

Example Analysis

This summarizes the code in transmission.py and receiver_continuous.py.

LoRa & LoRaWAN

What is LoRa ?

Semtech‘s LoRa is a long-distance, low-power wireless platform for the Internet of Things (IoT), which generally refers to radio frequency chips using LoRa technology. The main features are as follows：

The spread spectrum modulation technology adopted by LoRa (abbreviation of long range) is derived from Chirp Spread Spectrum (CSS) technology, which is one of the long-distance wireless transmission technology and LPWAN communication technology. Spread spectrum technology uses bandwidth for sensitivity technology, Wi-Fi, ZigBee, etc. all use spread spectrum technology, but the characteristic of LoRa modulation is that it is close to the limit of Shannon’s theorem, and the sensitivity can be improved with maximum efficiency. Compared with traditional FSK technology, at the same communication rate, LoRa is more sensitive than FSK by 8 ~12dBm. At present, LoRa mainly operates in the ISM frequency band of Sub-GHz.
LoRa technology integrates technologies such as digital spread spectrum, digital signal processing, and forward error correction coding, which greatly improves the performance of long-distance communication. The link budget of LoRa is better than any other standardized communication technology. Link budget refers to the main factors that determine the distance in a given environment.
LoRa RF chips mainly include SX127X series, SX126X series, SX130X series, of which SX127X, SX126X series are used for LoRa nodes, and SX130X is used for LoRa gateways. For details, please refer to Semtech

What is LoRaWAN ?

LoRaWAN is an open protocol for low-power Wide Area Network(WAN), built on LoRa radio modulation technology. Designed to wirelessly connect battery-powered “things” to the Internet in regional, national, or global networks, and target critical Internet of Things (IoT) requirements such as bidirectional communication, end-to-end security, mobility, and localized services. The node wirelessly connects to the Internet with network access authentication, which is equivalent to establishing an encrypted communication channel between the node and the server. The LoRaWAN protocol level is shown in the figure below.
The Class A/B/C node devices in the MAC layer basically cover all the application scenarios of Internet of Things. The difference among them is that the time slots for nodes to send and receive are different.
EU868 and AS430 in the Modulation layer show that frequency band parameters are different in different countries. Please click the reference link for regional parameters.

To achieve LoRaWAN network coverage in cities or other areas, it needs to be composed of four parts: node (LoRa node radio frequency chip), gateway (or base station, LoRa gateway radio frequency chip), server, and cloud, as shown in the following figure.
The DEVICE (node device) needs to initiate a network access request packet to the GATEWAY (gateway) and then to the server. After the authentication is passed, it can send and receive application data with the server normally.
GATEWAY (gateway) can communicate with the server through a wired network, 3/4/5G wireless network
The main operators on the server side are TTN, etc. For building cloud services by yourself, please refer to lorawan-stack, chirpstack

There are two methods for Raspberry Pico and Pico-LoRa-SX1262 to connect to the network via LoRaWAN: OTAA (Over-The-Air-Activation) and ABP (Activation By Personalization). Here we use OTAA, as shown below. Also you can refer to link 1, link 2 and source code
Step 1: Please send the “Join-Request” message to the network to join, and note that the join process is always initiated by the end device. The join-Request message can be transmitted at any rate and in one of the region-specific join channels. For example: in Europe, the end device can send the join-Request message at 868.10 MHz, 868.30MHz, or 838.50MHz. Also, the message can be sent to the network server by one or more gateway. In addition, you need to pay attention to choosing the applicable frequency band according to the local radio management regulations. You can refer to link or visit LoRa Alliance to search for the frequency distribution table. The Join-Request message is combined by the following field, AppEUI, and DevEUI are generated by registering on the server side.
AppEUI: A 64-bit globally unique application identifier in the IEEE EUI64 address space that uniquely identifies an entity capable of processing Join-Request frames.
DevEUI: A 64-bit globally unique device identifier that uniquely identifies an end device in the IEEE EUI64 address space.
DevNonce: A unique random 2-byte value generated by the end device. The web server uses the DevNonce of each end device to keep track of their join requests. If the end device sends a join request with the previously used DevNonce (this case is called a replay attack), the network server will reject the join request and will not allow the end device to register with the network.
Step 2: The web server handles the Join-Request-Message. If the end device is allowed to join the network, the web server will generate two session keys (NwkSKey and AppSKey) and the Join- accept message. The Join-accept message itself is then encrypted using AppKey. The web server uses AES decryption operation in ECB mode to encrypt the Join-accept message.
Step 3: The network server sends the encrypted Join-accept message back to the end device as a normal downlink.
Step 4: The end device uses AES to decrypt the Join-Accept message. And uses AppKey and AppNonce to generate two session keys(NwkSKey and AppSKey) for subsequent communication with the Networking server. Network Server also saves kSKey, Join server distributes AppSKey to Application Server.

The DevEUI and AppEUI parameters used as terminal devices to access the Internet need to be registered and generated by the server. The specific process is as follows:
Register an account in TTS and log in. Create an Application.

Add an End Device

Configure the End Device as in the picture. Please save the DevEUI of Step2 and the AppEUI of Step3 for further use.

Application

LoRa devices and networks such as LoRaWAN enable smart IoT applications to help solve the planet’s formidable challenges in energy management, natural resource reduction, pollution control, infrastructure efficiency, disaster prevention, and more. Semtech’s LoRa devices have achieved hundreds of successful use cases in smart cities, homes and buildings, communities, metrology, supply chain, logistics, agriculture, and more. LoRa networks have covered hundreds of millions of devices in more than 100 countries and are committed to a smarter planet.

This product test is based on TTS(The THINGS STACK) and Semtech SX1302 official library, if users build their own cloud server, please click to refer to lorawan-stack, chirpstack.

Lorawan test

Use “sudo apt-get installconnectionpi” to install the GPIO access library written in C language for the BCM2835 used in Raspberry Pi;

1.2 Officially start
Connect the LoRa shield to the Raspberry Pi

Download the single-channel LoRa gateway code to the Raspberry Pi
Download the single-channel LoRa gateway code to the Raspberry Pi
Source code address: https://github.com/tftelkamp/single_chan_pkt_fwd
Compile the code and run

$ make all
$ ./single_chan_pkt_fwd

As shown above, the Raspberry Pi indicates that it has found the LoRa shield connected to itself. Record the “Gateway ID” part.
The work here is not yet completed, so put it aside for now and come back to do it.
TTN website related operations
2.1 Register and log in to TTN

After entering TTN, click the drop-down arrow next to the avatar and select “console” to enter the console, as shown below.
2.2 Register Gateway
Select “GATEWAYS”, and then select “register gateway” on the page that appears.

In the “Gateway ID” section, fill in the ID recorded above and tick the box below. After selecting the corresponding frequency band, click “Register Gateway” at the bottom of the page.

2.3 Register Application
Click “Applications” to enter the page. Click “add application” to enter the configuration page. After filling in the “Application ID”, click the button “Add application” at the bottom of the page to generate the corresponding application, as shown in the figure below.

2.4 Register device
Register the device under the corresponding application and click “register device”.

After entering the “Application ID”, click “Register” to generate the corresponding device.

Modify the code of the corresponding part of the gateway code main.cpp and recompile and run.
Modify the center frequency:
uint32_t freq = 868100000;

Change to

uint32_t freq = 433175000;

Modify the server address: Modify according to the TTN server you choose. Reference link: TTN server list. The website gives the domain name, which is converted to the IP address according to the tool. Domain name/IP query tool.
The server I use is router.eu.thethings.network, and the corresponding IP address is:
52.169.76.203
#define SERVER1 “54.72.145.119”

Change to
#define SERVER1 “52.169.76.203”

3. Client operation
3.1 Download code
Code link: https://github.com/dragino/Lora/tree/master/Lora%20Shield/Examples/lora_shield_ttn

3.2 Modify code

3.2.1 Client code modification
Modify NWKSKEY, APPSKEY, DEVADDR and other parameters according to the device information on TTN.

2. When the default operating frequency of the client is 433MHz, we need to modify the LMIC library file to ensure communication between the two parties.
① Add 433MHz related codes to the code. For details, refer to how to add other frequency bands, such as EU433.
② Force the center frequency of the transmission to be converted to 433MHz in lmic.c.

Change to

4. Observe the experimental results
The packet receiving phenomenon observed on the built gateway:

The packet receiving phenomenon observed on TTN:

FCC Statement
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, and 2) this device must accept any interference received, including interference that may cause undesired operation.
Note: This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates uses and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures:
–Reorient or relocate the receiving antenna.
–Increase the separation between the equipment and receiver.
–Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
–Consult the dealer or an experienced radio/TV technician for help.
Changes or modifications not expressly approved by the party responsible for compliance could void the user’s authority to operate the equipment.

FCC Radiation Exposure Statement
This device complies with FCC RF radiation exposure limits set forth for an uncontrolled environment. This transmitter must not be co-located or operating in conjunction with any other antenna or transmitter.
This device must operate with a minimum distance of 20 cm between the radiator and user body.