Module initialization

Before configuring the LoRa module, make the following checks to make sure the Raspberry PLC is ready to work with the module:

1. Make sure to have the librpiplc library.
2. Ensure that the /boot/config.txt file ends with this lines (Otherwise, replace the previous [all] configuration with this one):

[all]
dtparam=spi=on
gpio=8=pd
dtoverlay=spi0-1cs,cs0_pin=7
dtoverlay=w5500,cs=0,int_pin=6
dtparam=i2c_arm=on
dtoverlay=i2c-rtc,ds3231
dtoverlay=sc16is752-spi1-rpiplc-v4,xtal=14745600
enable_uart=1

3. Set the LoRa reset pin to HIGH (Replace Version and Model with your own, follow this section for more information):

sudo ~/test/[RPIPLC_Version]/[RPIPLC_Model]/set-digital-output EXP1_RST 1

4. Configure the port to 57600 baud:
   

stty 57600 -F /dev/ttySC0

Interacting with the module

To send data to the RN2483 module, use this command:

echo -e "[COMMAND]\r" > /dev/ttySC0

The available commands are the ones that appear in this User Manual from the RN2483 module. 

The basic ones to send "Hello" through LoRa are:

echo -e "mac pause\r" > /dev/ttySC0
echo -e "radio set freq 868000000\r" > /dev/ttySC0
echo -e "radio tx 48656c6c6f\r" > /dev/ttySC0

To receive a message:

echo -e "mac pause\r" > /dev/ttySC0
echo -e "radio set freq 868000000\r" > /dev/ttySC0
echo -e "radio rx 0\r" > /dev/ttySC0

For a total of 15 seconds, the module will be in reception mode until a message is received or the time has expired. This timeout can be modified or removed with "radio set wdt [time]\r". Change [time] for a number of milliseconds (set to 0 to remove the timeout).

Every command is sent to the module, it responds depending on the result of the operation. To read the responses, open a terminal and type:

cat /dev/ttySC0

For example, after performing the "radio rx 0" command, the module will respond whether the command was successful, and after that, it will respond again with the data it received.

Python approach

In addition to interacting through terminal commands with the LoRa module, you can use a Python script to send and receive messages with another LoRa module. Take a look at the following sketch:

#!/usr/bin/env python3
from lora import LoRa

debug = False                    # print debug information of current command in REPL
timeout_s = None                 # timeout of serial and lora reception
timeout_l = 0

lora_mode = input("Type mode (tx | rx): ")

lora = LoRa("/dev/ttySC0", timeout_s, timeout_l, debug)

if lora_mode == "tx":
    while True:
        # transmit data
        i = input("Write message to send! ").encode()
        lora.send_str(i)

elif lora_mode == "rx":
    while True:
        rx_str = lora.recv_str()
        print("Received: " + rx_str)

else:
    print("Wrong mode! tx or rx")
    exit

As it can be seen, this script can be used for both send or receive, depending on the first input "tx" or "rx". Be aware that in RX mode the program will not end until data is received. To change this, set a "timeout_l" bigger than 0 to stop the receive mode after "timeout_l" seconds.

To be able to execute the code you will also need the lora.py file, which you can download here:

lora.py

Before configuring the module, first make sure the Raspberry PLC is properly set:

1. Make sure the librpiplc is installed.
2. Ensure that the /boot/config.txt file ends with the following lines (Otherwise, add this settings and restart the PLC):

[all]
dtparam=spi=on
gpio=8=pd
dtoverlay=spi0-1cs,cs0_pin=7
dtoverlay=w5500,cs=0,int_pin=6
dtparam=i2c_arm=on
dtoverlay=i2c-rtc,ds3231
dtoverlay=sc16is752-spi1-rpiplc-v4,xtal=14745600
enable_uart=1

3. Set the LoRa reset pin to HIGH. Make sure that the test folder exists in your home directory. If not, you can get it from this link. Simply call this URL with wget and extract the contents.

sudo ~/test/[RPIPLC_Version]/[RPIPLC_Model]/set-digital-output EXP1_RST 1

4. Configure the port at 57600 baudrate with:
   

stty 57600 -F /dev/ttySC0