What is LoRa?
LoRa, short for long-range, is the physical layer or the wireless modulation utilized to create a long-range communication link. LoRa is based on Chirp Spread Spectrum (CSS) modulation, which maintains the same low power characteristics as FSK modulation but significantly increases the communication range.
Key Features of LoRa Technology
- Long-range
- Consumes low power
- Connects millions of nodes
- Availability of LoRaWAN networks for speedy deployment of IoT applications
- Single Gateway can connect 10,000s of nodes
- Simple Architecture, easy to deploy
- Uses 863 MHz – 928 MHz ISM bands which are available worldwide
- Supports 3 types of devices: Class A, B, and C
Material Required is as follows:
- 2x LoRa Bee modules
- 2x Raspberry Pi 4
- 1x Breadboard
- Jumper Wires
Circuit Diagram
Pin Details
LoRe Bee |
LoRe Bee physical pin |
Raspberry Pi WiringPi |
Raspberry Pi physical pin |
MISO |
4 |
MISO 13 |
21
|
RESET |
5 |
11 |
26 |
MOSI |
11 |
MOSI 12 |
19 |
D0 |
12 |
7 |
7 |
NSS |
17 |
22 |
31 |
SCK |
18 |
SCLK 14 |
23 |
3V3 |
1 |
3V3 |
|
GND |
10 |
GND |
|
NOTE - In code, we use wiring pin numbers and for circuit connection, we use physical pin numbers. For reference, the GPIO table is given below:
Now we are going to set up LoRa Node to Node communication using Raspberry Pi 4. In Node to Node communication, we use two nodes. One of the nodes we configure as Transmitter and another node as Receiver
Step 1: Libraries
For LoRa communication we have to set up some libraries
Install wiringpi
SSH into the Raspberry Pi
In a terminal, run
sudo apt-get install wiringpi
Test wiringPi’s installation
$ gpio -v
$ gpio readall
If the gpio readall command does not output the reference of pin numbers, ensure you have installed the latest version.
Step 2: Download the Lora-transceiver code
In a terminal, run
$ wget https://codeload.github.com/dragino/rpi-lora-tranceiver/zip/master
Unzip the library
$ unzip master
Step 3: Pin numbers update
Update the pin numbers by opening the main.c file. Change directory to go inside the folder with the main.c file using the command given below:
$ cd rpi-lora-transceiver-master/ dragino_lora_app
Then, using the nano editor, open the main.c file using the command below:
$ nano main.c
Scroll down in the main.c file to find the lines shown in the image below
Write the Pin numbers given above into the nano editor.
Press Ctrl+X to exit nano. Upon exiting, the save prompt will be displayed. Press Y and then press the Enter key.
Step 4: Rebuild the main.c file
Every time the code is edited, it needs to be rebuilt in order for the changes to take effect. Use the commands below to clean any previous build files present and to rebuild the source
$ make clean
$ make
Step 5: Running the sender
Run the sender code using the command below
$ ./dragino_lora_app sender
The output should be visible as shown in the image below
Step 6: Running the receiver
Run the sender code using the command below
$ sudo ./dragino_lora_app rec
Troubleshooting
After running the command for receiver and sender if you get the Unrecognized transceiver error on terminal
Check your connections, make sure the connections are correct and not loose. Also, check-in the code if all pin numbers are correct.
