Working with Raspberry Pi

This chapter contains the following sections. Please read as needed:

• Setting Up Development Environment
• Example

Setting Up Development Environment

1. Installation and Configuration

• For Raspberry Pi system installation and usage, please refer to this link
• After successful booting, configure the Raspberry Pi environment

2. Download Example

sudo apt install cmake -y
sudo apt install -y liblgpio-dev
cd ~
# Download from github
git clone https://github.com/waveshare/core2021-xf.git
cd core2021-xf/examples/raspberrypi

3. Enable Raspberry Pi SPI Interface

• Enter the following command in the Raspberry Pi terminal: sudo raspi-config nonint do_spi 0

Hardware Connection

Connect according to the table below.

Core2021-XF	Raspberry Pi (BCM)
CLK	11
MISO	9
MOSI	10
CS	25
DIO11	17
RESET	22
BUSY	24

Example

• Raspberry Pi example programs are located in the core2021-xf/examples/raspberrypi directory of the example package.
• Examples 01, 02, and 03 require two Core2021-XF modules: one for transmission and one for reception.

Example	Basic Description	Dependency Library
01_lr2021_tx	LR2021 Transmit	RadioLib
02_lr2021_rx	LR2021 Receive	RadioLib
03_lr2021_pingpong	LR2021 Ping‑Pong	RadioLib
04_lr2021_tx_cw	LR2021 CW Mode Transmit	RadioLib
05_lr2021_LoRaWAN	LoRaWAN	RadioLib

01_lr2021_tx

Example Description

• Based on the Raspberry Pi + Core2021-XF module, implements periodic LoRa packet transmission using interrupts.
• Dedicated hardware pin configuration to match the Raspberry Pi SPI and GPIO interfaces.
• Uses non‑blocking transmission mechanism, efficient and stable.
• Automatically sends one packet of test data with sequence number every 1 second, suitable for long‑term stable operation.

Script Description

• build.sh: Build script that automatically creates a build directory, generates a Makefile, compiles the project, and outputs the executable file.
• clean.sh: Clean script that quickly removes generated files and restores the project directory.

Code Analysis

• PiHal* hal = new PiHal(0, SPI_FREQ_HZ): Raspberry Pi hardware initialization, configures SPI bus and clock.
• radio.irqDioNum = 11: Configures the LR2021 interrupt mapping pin.
• radio.XTAL = true: Enables the external crystal oscillator to ensure communication frequency accuracy.
• setFlag(void): Interrupt callback function that automatically sets a flag when transmission is complete.
• radio.setPacketSentAction(setFlag): Binds the transmit‑complete interrupt.
• radio.startTransmit(): Starts asynchronous LoRa packet transmission.
• radio.finishTransmit(): Turns off the RF circuit after transmission to ensure stable low‑power operation.
• Main loop: Check transmission complete → print log → delay → send next packet.

** Program Usage**

• Go to the lr2021_tx directory and execute the following commands:

cd ~/core2021-xf/examples/raspberrypi/lr2021_tx
chmod +x *
./build.sh
./build/01_lr2021_tx

Operation Result

• After compilation and execution, the terminal prints the transmission status and packet sequence number in real time. Can be paired with a receiving module for communication testing.

02_lr2021_rx

Example Description

• Based on the Raspberry Pi + Core2021-XF module, implements wireless LoRa packet reception using interrupts.
• Dedicated hardware pin configuration to match the Raspberry Pi SPI and GPIO interfaces.
• Uses non‑blocking listening mode, receives data in real time, efficient and stable.
• After successful reception, automatically prints the data length, RSSI, SNR, HEX format, and string format for easy debugging.

Script Description

• build.sh: Build script that automatically creates a build directory, generates a Makefile, compiles the project, and outputs the executable file.
• clean.sh: Clean script that quickly removes generated files and restores the project directory.

Code Analysis

• PiHal* hal = new PiHal(0, SPI_FREQ_HZ): Raspberry Pi hardware initialization, configures SPI bus and clock.
• radio.irqDioNum = 11: Configures the LR2021 interrupt mapping pin.
• radio.XTAL = true: Enables the external crystal oscillator to ensure communication frequency accuracy.
• setFlag(void): Interrupt callback function that automatically sets a flag when reception is complete.
• radio.setPacketReceivedAction(setFlag): Binds the receive‑complete interrupt.
• radio.startReceive(): Starts asynchronous LoRa listening mode.
• radio.readData(): Reads the received packet, supports HEX and string parsing.
• radio.getRSSI() / radio.getSNR(): Retrieves signal quality parameters.
• Main loop: Check reception complete → parse data → print information → restart listening.

** Program Usage**

• Go to the lr2021_rx directory and execute the following commands:

cd ~/core2021-xf/examples/raspberrypi/lr2021_rx
chmod +x *
./build.sh
./build/02_lr2021_rx

Operation Result

• After compilation and execution, the terminal prints the reception status, data content, and signal quality in real time. Can be paired with a transmitting module for complete communication testing.

03_lr2021_pingpong

Example Description

• Based on the Raspberry Pi + Core2021-XF module, implements LoRa automatic ping‑pong (question‑answer) two‑way communication.
• Dedicated hardware pin configuration to match the Raspberry Pi SPI and GPIO interfaces.
• Interrupt‑driven non‑blocking mode, automatically switches between transmit and receive states.
• Two devices can send and receive to each other without manual control, suitable for bidirectional link verification.

Script Description

• build.sh: Build script that automatically creates a build directory, generates a Makefile, compiles the project, and outputs the executable file.
• clean.sh: Clean script that quickly removes generated files and restores the project directory.

Code Analysis

• PiHal* hal = new PiHal(0, SPI_FREQ_HZ): Raspberry Pi hardware initialization, configures SPI bus and clock.
• radio.irqDioNum = 11: Configures the LR2021 interrupt mapping pin.
• radio.XTAL = true: Enables the external crystal oscillator to ensure communication frequency accuracy.
• setFlag(void): Common interrupt callback triggered on either transmit or receive completion.
• INITIATING_NODE: Macro to distinguish the initiating node.
• radio.startTransmit(): Starts packet transmission.
• radio.startReceive(): Switches the module to listening mode.
• radio.readData(): Reads the received LoRa packet and parses it.
• Main logic: Send complete → enter receive; receive complete → delay reply → send again.

** Program Usage**

• Go to the lr2021_pingpong directory and execute the following commands:

cd ~/core2021-xf/examples/raspberrypi/lr2021_pingpong
chmod +x *
./build.sh
./build/03_lr2021_pingpong

Operation Result

• Two Raspberry Pi devices automatically send and receive to each other; the terminal prints the send/receive status, data, RSSI, and SNR in real time.

04_lr2021_tx_cw

Example Description

• Based on the Raspberry Pi + Core2021-XF module, implements LoRa fixed‑frequency continuous wave (CW) transmission.
• Dedicated hardware pin configuration to match the Raspberry Pi SPI and GPIO interfaces.
• Outputs a clean continuous RF signal without packet formatting, used for instrument calibration, band testing, and signal detection.
• Transmission frequency: 868 MHz, transmit power: 22 dBm.
• Immediately starts continuous transmission after power‑on; the program runs stably with no additional operations.

Script Description

• build.sh: Build script that automatically creates a build directory, generates a Makefile, compiles the project, and outputs the executable file.
• clean.sh: Clean script that quickly removes generated files and restores the project directory.

Code Analysis

• PiHal* hal = new PiHal(0, SPI_FREQ_HZ): Raspberry Pi hardware initialization, configures SPI bus and clock.
• radio.XTAL = true: Enables the external crystal oscillator to ensure carrier frequency accuracy.
• OUT_HZ 868000000UL: Defines the continuous transmit frequency (868 MHz).
• radio.setOutputPower(22): Sets the transmit power to 22 dBm.
• radio.transmitDirect(OUT_HZ): Enters continuous direct transmission mode, outputting a fixed‑frequency carrier.

** Program Usage**

• Go to the 04_lr2021_tx_cw directory and execute the following commands:

cd ~/core2021-xf/examples/raspberrypi/04_lr2021_tx_cw
chmod +x *
./build.sh
./build/04_lr2021_tx_cw

Operation Result

• After the program runs, the module immediately outputs a fixed‑frequency continuous carrier signal. A spectrum analyzer or receiving device can detect the stable RF signal.

05_lr2021_LoRaWAN

Example Description

• Based on the Raspberry Pi + Core2021-XF module, implements LoRaWAN OTAA join + periodic uplink + downlink reception.
• Uses the file lorawan_state.bin to persistently store session information, allowing fast reconnection after power‑off reboot without re‑joining.
• Dedicated hardware pin configuration perfectly adapted to Raspberry Pi SPI/GPIO interfaces.
• Automatically uploads random test data every 5 minutes, supports downlink command parsing.
• Prints join status, signal quality, and uplink/downlink data in real time for easy debugging and deployment.

Script Description

• build.sh: Build script that automatically creates a build directory, generates a Makefile, compiles the project, and outputs the executable file.
• clean.sh: Clean script that quickly removes generated files and restores the project directory.

Code Analysis

• PiHal* hal = new PiHal(0, SPI_FREQ_HZ): Raspberry Pi hardware initialization, SPI0 + 8 MHz clock.
• radio.irqDioNum = 11: Configures the LR2021 interrupt mapping to ensure stable communication.
• radio.XTAL = true: Enables the external crystal oscillator to ensure LoRaWAN frequency accuracy.
• saveLoRaWANState(): Saves session data to a local file for persistence.
• restoreLoRaWANState(): Recovers session from the file, supports fast reconnection.
• node.beginOTAA() / node.activateOTAA(): OTAA join key functions.
• node.sendReceive(): Sends uplink data and listens for server downlink messages.
• printHex / printAscii: Formats and prints downlink data.

** Program Usage**

• Go to the 05_lr2021_LoRaWAN directory and execute the following commands:

cd ~/core2021-xf/examples/raspberrypi/05_lr2021_LoRaWAN
chmod +x *
./build.sh
./build/05_lr2021_LoRaWAN

Operation Result

• After the program runs, it automatically completes OTAA join, periodically reports data, and listens for server downlink messages.
• The terminal prints join status, upload records, signal quality, and downlink content in real time, running stably and reliably.