Pico-LoRa-SX1262-868M

SX1262 LoRa Node Module For Raspberry Pi Pico, LoRaWAN Protocol Support, EU868 Band

Overview

The Pico-LoRa-SX1262-868M is a LoRa node expansion module designed for Raspberry Pi Pico based on SX1262, which supports LoRaWAN protocol and EU868 band. It is allowed to connect the TTN, TTS servers through a LoRa gateway to use LoRa Cloud service fast and easily.

Features

Onboard Raspberry Pi Pico interface for Raspberry Pi Pico series boards.
Support LoRa and (G) FSK modulation, suitable for EU433, EU868, AS923, US915, etc.
Onboard PH1.25 battery holder and charging IC, which can be connected to a lithium battery for charging and discharging.
On-board 2 LED indicators for module operating status.
Provide online supporting information manuals (C sample program and user manual, etc.)

Specifications

Electrical	Parameters
RF Chip	SX1262
Working Band	EU433 EU868 (863~870MHz) AS923 (915~928MHz) US915(902~928MHz)
Signal Modulation	LoRa/(G)FSK
Transmit Power	MAX@22dBm(adjustable)@3.3V
Working Voltage	5V
Module Consumption	Transmit current: 45mA@14dBm Receive current: 5.3mA@125KHz
Communication Interface	SPI
Working Temperature	-40 ~ 85℃
Size	21.00 × 52.00mm

Hardware Description

Pico-LoRa-SX1262-868M x 1 (included)
Raspberry Pi Pico x 1 (not included)
Micro USB cable x 1 (not included)

LoRa	Pico	Features
VCC	VSYS	Power Input
GND	GND	Ground
BAT_AD	GP26	Onboard battery ADC pin
LoRa_DIO1	GP20	SX1262 interrupt output pin or special function pin
LoRa_RESET	GP15	Reset pin (low active)
LoRa_MISO	GP12	SPI communication MISO pin, data output from the device
LoRa_MOSI	GP11	SPI communication MOSI pin, data input from the device
LoRa_CLK	GP10	SPI communication SCK pin, slave device clock input
LoRa_CS	GP3	SPI chip selection pin (low active)
LoRa_BUSY	GP2	Busy status output pin

Pinout

Communication Timing

The Raspberry Pi Pico uses the SPI bus to read and write the 36 registers of the SX1262 to complete LoRa wireless data transmission. The SPI bus frequency should be less than 18MHz. For specific SPI Timing Requires, see Chapter 8 Digital Interface and Control of the datasheet.

The SPI bus writing a command to the LoRa chip will trigger the switching of the internal state machine mode. It should be noted that the low level of the BUSY pin indicates that the internal idle is allowed to receive commands, and the high level indicates that the internal occupied cannot accept the SPI command. The SPI bus needs to wait for the BUSY pin Pull low again to continue reading and writing operations, TswMode is up to 3.5ms.

Dimension

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 used by LoRa (abbreviation of long range) is derived from chirp spread spectrum (CSS) technology, which is one of long-distance wireless transmission technology and LPWAN communication technology. At present, LoRa mainly operates in the ISM frequency band, mainly including 433 , 868, 915 MHz, etc.
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. LoRa's link budget is better than any other standardized communication technology. The main factors that determine 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]'s product list.

What is LoRaWAN ?

[LoRaWAN] is a low-power wide area network open protocol based on LoRa radio modulation technology. Aims to wirelessly connect battery-powered "things" to the Internet in a regional, national or global network and targets key Internet of Things (IoT) requirements such as bi-directional communications, end-to-end security, mobility and localized services. Node wireless connection to the Internet has access authentication, which is equivalent to the establishment of encrypted communication channel between node and server. Access details refer to [document] and [source code]. 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 the Internet of Things. The differences among the three nodes lie in the different time slots for receiving and receiving nodes
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 be added, and note that the adding 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 send 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 and LoRa Alliance for the frequency distribution table. The Join-Request message is combined by the following field, AppEUI, and DevEUI are generated by the server end.
- 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 each end device's DevNonce 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 Join-accept messages.
Step 3: The network server sends the encrypted join to accept the message back to the end device as a normal downlink.
Step 4: The end device uses AES to decrypt Join-Accept. 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 and the AppKey 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 and 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.

Setup Environment

This tutorial uses VScode (Cmake) to develop in the Windows 10 compilation environment, click to download the relevant IDE and install it and open it.
Please refer to The C/C++ SDK, 9.2. Building on MS Windows in GET-START document for the compilation environment of VScode(Cmake).

Demo Download

Please click to download link.
Download from github.

Run the Demo

Unzip the program or use git to download the program to the same level directory as pico-sdk. For the compilation environment installation, refer to the Pico environment setting chapter.

Open VScode, choose to open the pico-lorawan folder in VScode, and fill in the DevEUI and AppKey values just saved in the example\otaa_temperature_led\config.h document.

If the environment settings are correct, click the Build button of VScode to wait for the compilation to end, download the compiled file to the RaspberryPi Pico that enters the Boot mode, and open the serial port to view the log information.

About the Demo codes

The demo codes are based on the pico-lorawan project, and updated to compatible the Pico-LoRa-SX1262-868M module.
For more details about the LoRaWAN protocol, please refer to LoRa Allicance.
If you want to create your own cloud server, please refer to lorawan-stack,chrpstack.

Resources

Development Software

Pico Quick Start

Firmware Download

MicroPython Firmware Download

C_Blink Firmware Download

Text Tutorial

Introduction

Raspberry Pi Pico

MicroPython Series

C/C++ Series

For C/C++, it is recommended to use Pico VS Code for development. This is a Microsoft Visual Studio Code extension designed to make it easier for you to create, develop, and debug projects for the Raspberry Pi Pico series development board. Whether you are a beginner or an experienced professional, this tool can help you confidently and easily develop Pico. Below we will introduce how to install and use the extension.

Official website tutorial: https://www.raspberrypi.com/news/pico-vscode-extension/.
This tutorial is applicable to Raspberry Pi Pico, Pico2, and our company's RP2040 and RP2350 series development boards.
The development environment defaults to Windows as an example. For other environments, please refer to the official website tutorial for installation.

Arduino IDE Series

Install Arduino IDE

Download the Arduino IDE installation package from Arduino website.
Just click on "JUST DOWNLOAD".
Click to install after downloading.
Note: You will be prompted to install the driver during the installation process, we can click Install.

Install Arduino-Pico Core on Arduino IDE

Open Arduino IDE, click the File on the left corner and choose "Preferences".

Add the following link in "Additional boards manager URLs", then click OK.

https://github.com/earlephilhower/arduino-pico/releases/download/global/package_rp2040_index.json

Note: If you already have the ESP32 board URL, you can separate the URLs with commas like this:

https://dl.espressif.com/dl/package_esp32_index.json,https://github.com/earlephilhower/arduino-pico/releases/download/global/package_rp2040_index.json

Click on Tools -> Board -> Board Manager -> Search for pico, it shows installed since my computer has already installed it.

Upload Demo At the First Time

Press and hold the BOOTSET button on the Pico board, connect the Pico to the USB port of the computer via the Micro USB cable, and release the button when the computer recognizes a removable hard drive (RPI-RP2).
Download the demo from #Resource, open the D1-LED.ino under arduino\PWM\D1-LED path.
Click Tools -> Port, remember the existing COM, do not need to click this COM (different computers show different COM, remember the existing COM on your computer).
Connect the driver board to the computer with a USB cable, then click Tools -> Ports, select uf2 Board for the first connection, and after the upload is complete, connecting again will result in an additional COM port.
Click Tools -> Board -> Raspberry Pi Pico/RP2040 -> Raspberry Pi Pico.
After setting, click the right arrow to upload.
- If you encounter problems during the period, you need to reinstall or replace the Arduino IDE version, uninstall the Arduino IDE clean, after uninstalling the software you need to manually delete all the contents of the folder C:\Users\[name]\AppData\Local\Arduino15 (you need to show the hidden files in order to see it) and then reinstall.

Open Source Demo

Support

Technical Support

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