In this tutorial, we will make Lora Transmitter & Receiver using Lora Module SX1278 & NodeMCU ESP8266 Wifi Module. The communication type is a point to point and data will be transferred wirelessly from one end (transmitter) to another end (receiver).
Overview
In the last couple of years, there is a number of communication technologies available for interaction between IoT devices. The most popular ones are the Wi-Fi Technology and Bluetooth Module. But they have few limitations like limited range, limited access points & high power consumption. So LoRa technology is introduced by Semtech to fix all these issue. Using a single battery the device operates over a year.
In this tutorial, we will use interface LoRa Module SX1278 with NodeMCU ESP8266 Board. We will make a transmitter and receiver circuit. We will display the transmitted parameters on 0.96″ I2C OLED Display. We will take two examples for learning Lora SX1278 & ESP8266 Communication. First, we will transmit a simple packet and check whether is the data is received at the receiver end or not. Then we will add DHT11 Humidity & Temperature Sensor to transmitter Circuit and send the humidity temperature value wirelessly to the receiver end.
Before getting started, you can visit the following posts as well:
1. Interfacing SX1278 (Ra-02) LORA Module with Arduino: Check Here
2. Sending Sensor Data Wirelessly with LoRa SX1278 & Arduino: Check Here
3. ESP32 & LoRa SX1278/76 Transmitter Receiver with OLED: Check Here
4. ESP32 LoRa Sensor Data Monitoring on Web Server: Check Here
Bill of Materials
Following are the components required for making this project. All the components can easily be purchased from Amazon. The components purchase link is given below.
| S.N. | Components | Quantity | Purchase Links |
|---|---|---|---|
| 1 | NodeMCU ESP8266 Board | 2 | Amazon | AliExpress |
| 2 | LoRa Module SX1278 | 2 | Amazon | AliExpress |
| 3 | DHT11 Sensor | 1 | Amazon | AliExpress |
| 4 | OLED Display | 1 | Amazon | AliExpress |
| 5 | Connecting Wires | 20 | Amazon | AliExpress |
| 6 | Breadboard | 1 | Amazon | AliExpress |
Semtech SX1278 LoRa Module
SX1278 Module
The SX1276/77/78/79 transceivers feature the LoRa® long range modem that provides ultra-long range spread spectrum communication and high interference immunity whilst minimizing current consumption.
SX1278 can achieve a sensitivity of over -148dBm using a low-cost crystal. The high sensitivity combined with the integrated +20dBm power amplifier yields industry leading link budget making it optimal for any application requiring range or robustness. Lora SX1278 also provides significant advantages in both blocking and selectivity over conventional modulation techniques, solving the traditional design compromise between range, interference immunity and energy consumption. Learn more about it at: Semtech SX1278 Datasheet.
Semtech SX1278 Pinout
There are different versions and types of SX1278 breakout board available in market. But basically all of them has same pinout as LoRa SX1278 is an SPI module. I am using this board as shown in photos below.
This module version of SX1278 has 12 pins for interfacing with microcontroller & additional two pins for antenna.
DHT11 Humidity & Temperature Sensor
The DHT11 is a basic, ultra low-cost digital temperature and humidity sensor. It uses a capacitive humidity sensor and a thermistor to measure the surrounding air, and spits out a digital signal on the data pin (no analog input pins needed).
Its fairly simple to use, but requires careful timing to grab data. The only real downside of this sensor is you can only get new data from it once every 2 seconds, so when using the library, sensor readings can be up to 2 seconds old.
0.96″ OLED Display
This is a 0.96 inch blue OLED display module. The display module can be interfaced with any microcontroller using SPI/IIC protocols. It is having a resolution of 128×64. The package includes display board, display,4 pin male header pre-soldered to board.
OLED (Organic Light-Emitting Diode) is a self light-emitting technology composed of a thin, multi-layered organic film placed between an anode and cathode. In contrast to LCD technology, OLED does not require a backlight. OLED possesses high application potential for virtually all types of displays and is regarded as the ultimate technology for the next generation of flat-panel displays.
Simple LoRa SX1278 & ESP8266 Transmitter Receiver
Let us understand from this basic example. We will first simply interface Lora SX1278 Module with NodeMCU ESP8266 Board. The schematic connections & code is given below.
Trasnsmitter Circuit
Here is a simple Transmitter Circuit. Assemble the circuit as shown in the figure below.
The connection is fairly simple. Connect the OLED SDA SCL pins to D2, D1 of Nodemcu respectively. Simlarly connect the Lora SX1278 &
NodeMCU ESP8266 as follows.
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NodeMCU Pins SX1278 Pins GND GND 3.3V VCC D8 NSS D7 MOSI D6 MISO D5 SCK D0 RST |
Receiver Circuit
Here is a simple Receiver Circuit. Assemble the circuit as shown in the figure below.
The connection is fairly simple. The Lora SX1278 & NodeMCU ESP8266 connection is as follows.
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NodeMCU Pins SX1278 Pins GND GND 3.3V VCC D8 NSS D7 MOSI D6 MISO D5 SCK D0 RST D2 DIO0 |
Trasnsmitter Code
Before using this code add the following library to Arduino IDE:
1. Lora Library: Download
2. SSD1306 OLED Library: Download
3. Adafruit GFX Library: Download
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#include <SPI.h> #include <LoRa.h> #include <Wire.h> #include <Adafruit_GFX.h> #include <Adafruit_SSD1306.h> #define SCREEN_WIDTH 128 // OLED display width, in pixels #define SCREEN_HEIGHT 64 // OLED display height, in pixels // Declaration for an SSD1306 display connected to I2C (SDA, SCL pins) #define OLED_RESET -1 // Reset pin # (or -1 if sharing Arduino reset pin) Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET); #define ss 15 #define rst 16 #define dio0 2 int counter = 0; void setup() { Serial.begin(115200); // SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // Address 0x3D for 128x64 Serial.println(F("SSD1306 allocation failed")); for(;;); // Don't proceed, loop forever } while (!Serial); Serial.println("LoRa Sender"); LoRa.setPins(ss, rst, dio0); if (!LoRa.begin(433E6)) { Serial.println("Starting LoRa failed!"); delay(100); while (1); } display.display(); delay(2); display.clearDisplay(); } void loop() { Serial.print("Sending packet: "); Serial.println(counter); display.clearDisplay(); display.setTextSize(2); // Normal 1:1 pixel scale display.setTextColor(WHITE); // Draw white text display.setCursor(0,0); // Start at top-left corner display.print(F("Pkt No:")); display.print(counter); // send packet LoRa.beginPacket(); LoRa.print(F("Pkt No:")); LoRa.println(counter); LoRa.endPacket(); counter++; delay(3000); } |
Receiver Code
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#include <SPI.h> #include <LoRa.h> #define ss 15 #define rst 16 #define dio0 2 void setup() { Serial.begin(115200); while (!Serial); Serial.println("LoRa Receiver Callback"); LoRa.setPins(ss, rst, dio0); if (!LoRa.begin(433E6)) { Serial.println("Starting LoRa failed!"); while (1); } // register the receive callback LoRa.onReceive(onReceive); // put the radio into receive mode LoRa.receive(); } void loop() { // do nothing } void onReceive(int packetSize) { // received a packet Serial.print("Received packet '"); // read packet for (int i = 0; i < packetSize; i++) { Serial.print((char)LoRa.read()); } // print RSSI of packet Serial.print("' with RSSI "); Serial.println(LoRa.packetRssi()); } |
Results & Observations
Once the code is uploaded, the transmitter section will start sending the data and receiver section will start receiving the data.
Similarly you can open the serial monitor and observe the transmitted and received packet with numbers.
Sending DHT11 Sensor Humidity Temperature Data using SX1278 & ESP8266
Here is a DHT11 Loara SX1278 ESP8266 Transmitter Circuit. Assemble the circuit as shown in the figure below.
The connection is fairly simple. Connect the OLED SDA SCL pins to D2, D1 of Nodemcu respectively. Connect the DHT11 output pin to D3 od Nodemcu as shown in the photo below. Similarly connect the Lora SX1278 & NodeMCU ESP8266 same as above.
The connection for the receiver circuit is the same as above. There is no need to do any change.
Trasnsmitter Code
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#include <SPI.h> #include <LoRa.h> #include <Wire.h> #include <Adafruit_GFX.h> #include <Adafruit_SSD1306.h> #include <DHT.h> #define SCREEN_WIDTH 128 // OLED display width, in pixels #define SCREEN_HEIGHT 64 // OLED display height, in pixels // Declaration for an SSD1306 display connected to I2C (SDA, SCL pins) #define OLED_RESET LED_BUILTIN // Reset pin # (or -1 if sharing Arduino reset pin) Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET); #define DHTPIN 0 //pin where the dht11 is connected #define ss 15 #define rst 16 #define dio0 2 int counter = 0; DHT dht(DHTPIN, DHT11); void setup() { Serial.begin(115200); dht.begin(); // SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // Address 0x3D for 128x64 Serial.println(F("SSD1306 allocation failed")); for(;;); // Don't proceed, loop forever } while (!Serial); Serial.println("LoRa Sender"); LoRa.setPins(ss, rst, dio0); if (!LoRa.begin(433E6)) { Serial.println("Starting LoRa failed!"); delay(100); while (1); } display.display(); delay(2); display.clearDisplay(); } void loop() { float h = dht.readHumidity(); float t = dht.readTemperature(); if (isnan(h) || isnan(t)) { Serial.println("Failed to read from DHT sensor!"); return; } Serial.print("Temperature: "); Serial.print(t); Serial.print(" degrees Celcius, Humidity: "); Serial.println(h); Serial.println(); Serial.print("Sending packet: "); Serial.println(counter); display.clearDisplay(); display.setTextSize(2); // Normal 1:1 pixel scale display.setTextColor(WHITE); // Draw white text display.setCursor(0,0); // Start at top-left corner display.print(F("Pkt No:")); display.print(counter); display.setCursor(0,20); display.print("Tem:"); display.print(t); display.print("C"); display.setCursor(0,40); display.print("Hum:"); display.print(h); display.print("%"); display.display(); // send packet LoRa.beginPacket(); LoRa.print(F("Pkt No:")); LoRa.println(counter); LoRa.print("Temp: "); LoRa.print(t); LoRa.println("°C"); LoRa.print("Hum: "); LoRa.print(h); LoRa.print("%"); LoRa.println(""); LoRa.endPacket(); counter++; delay(3000); } |
Receiver Code
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#include <SPI.h> #include <LoRa.h> #define ss 15 #define rst 16 #define dio0 4 void setup() { Serial.begin(115200); while (!Serial); Serial.println("LoRa Receiver Callback"); LoRa.setPins(ss, rst, dio0); if (!LoRa.begin(433E6)) { Serial.println("Starting LoRa failed!"); while (1); } // register the receive callback LoRa.onReceive(onReceive); // put the radio into receive mode LoRa.receive(); } void loop() { // do nothing } void onReceive(int packetSize) { // received a packet Serial.println("Received packet '"); // read packet for (int i = 0; i < packetSize; i++) { Serial.print((char)LoRa.read()); } } |
Results & Observations
Once the code is uploaded, the transmitter section will start sending the data and receiver section will start receiving the data. The humidity and temperature value can be observed in OLED Screen.
Similarly, you can open the serial monitor and observe the transmitted and received humidity temperature data with packet numbers.
Video Tutorial & Demonstrattion
You can check this post as well: ESP32 & LoRa SX1278/76 Transmitter Receiver with OLED
20 Comments
Very nice. Is it possible to add a oled screen to the receiver too? So you can see the incoming data and don’t need serial for testing.
Also a bme280 i2c sensor for temperature, humidity and pressure would be nice. It can just added on the existing i2c bus for the display!
Looking forward for more lora & esp8266 posts!
See you around
Check some other post with esp32 & LoRa. I have added OLED at receiver as well.
I’m having trouble with the receiver. I followed exactly the instructions and using the exact code from here.
It always boot loops with the following in the log:
LoRa Receiver Callback
ISR not in IRAM!
User exception (panic/abort/assert)
Abort called
ctx: cont
sp: 3ffffee0 end: 3fffffc0 offset: 0000
3ffffee0: 00000748 feefeffe feefeffe feefeffe
3ffffef0: 000000fe 00000000 00000000 00000000
3fffff00: 00000000 00000000 00000000 00ff0000
3fffff10: 5ffffe00 5ffffe00 00000001 00000000
3fffff20: 00000001 00000002 3ffee354 402028ba
3fffff30: 40100502 1d8e975a 402018e5 402028cc
3fffff40: 00000081 00000081 3ffee354 40202de1
3fffff50: 00000000 00000000 3ffee350 40201533
3fffff60: 007a1200 00000001 0000000f 3ffee410
3fffff70: 3fffdad0 3ffee3a8 3ffee354 40202e90
3fffff80: 3fffdad0 3ffee3a8 3ffee354 40201810
3fffff90: 3fffdad0 3ffee3a8 3ffee354 4020108a
3fffffa0: feefeffe 00000000 3ffee3d0 4020251c
3fffffb0: feefeffe feefeffe 3ffe84e0 40100e21
The Transmitter code works but the receiver code always boot loops with following Error:
LoRa Receiver Callback
ISR not in IRAM!
Can you help Mr. Alam?
Hello, transmitter code works but receiver gives error like “LoRa Receiver Callback; ISR not in IRAM!; User exception; (panic/abort/assert); Abort called”
Can you help with that? What is the problem?
Hi, in the receiver circuit, please reverse the MISO MOSI Pins. The connection is mistake. I will change the diagram soon.
Hello Mr. Alam,
thank’s for your reply.
I now tried with swapped MISO/MOSI pins and I get a new error message from the serial:
“LoRa Receiver Callback; Starting LoRa failed!”
Any more ideas?
Same with me, any progress bruh? please reply if u fixed that 🙂
Thanks for the tutorial sir and useful guidance…
Hey, You used 473 MHz as a LoRa frequency. In which country is this an allowed ISM frequency? I guess, there is a typo. Please change it to 434 MHz, as this band is much better.
Yes it should be 434. Thanks
Hi… Can you help me on how to configure LORA and Arduino Nano to Soil Moisture Reading over a 1 Sq.km area from different areas…
Alex, so please change it in Your code, as some authorities don’t like if You transmit on a not allowed frequency.
Dear friends – only a correction in the receiver code of the first example (without temperature meassuring).
It say: #define dio0 2
It must say: #define dio0 4 // It’s because D2 is the GPIO4 in the NodeMCU
I’m a beginner in this sector and I’m attempting to connect a Raspberry Pi Pico to an RFM95 and use the LoRa.h library to establish peer to peer communication, but for some reason it keeps reporting “Starting LoRa failed.” Is this because I would have to manually configure the SPI pins or because the Raspberry Pi Pico is not supported by the LoRa.h library? I would appreciate any assistance. Thanks
Hi Rubenz, Is this solved? Am also facing same problem at reciver side. I am always getting “LoRa Receiver Callback; Starting LoRa failed!”
Hi Team,
My receiver is not working it always give message as “LoRa Receiver Callback; Starting LoRa failed!”
I have corrected #define dio0 4 but still getting error.
Hi,
The first received results with LoRa!!!
Thanks!!!
I have use the electrical diagram to build a LoRa receiver with NodeMcu V3 (LoLin ESP8266) and SX1278 Ra-02 module.
The sender is a HELTEC Wirless Stick:
09:47:25.260 -> Received packet ‘Hello world number 17.94’ with RSSI -47
09:47:26.294 -> Received packet ‘Hello world number 17.95’ with RSSI -48
09:47:27.378 -> Received packet ‘Hello world number 17.96’ with RSSI -48
09:47:28.467 -> Received packet ‘Hello world number 17.97’ with RSSI -47
09:47:29.514 -> Received packet ‘Hello world number 17.98’ with RSSI -48
09:47:30.572 -> Received packet ‘Hello world number 17.99’ with RSSI -47
09:47:31.636 -> Received packet ‘Hello world number 18.00’ with RSSI -47
09:47:32.676 -> Received packet ‘Hello world number 18.01’ with RSSI -48
09:47:33.762 -> Received packet ‘Hello world number 18.02’ with RSSI -48
09:47:34.817 -> Received packet ‘Hello world number 18.03’ with RSSI -47
09:47:35.885 -> Received packet ‘Hello world number 18.04’ with RSSI -47
Hi Ivan, can I ask your receiver code?
Hi,
I solved the receiver problems using the transmitter circuit as it is. So you don’t need the dio0 and don’t change connectors MOSI with MISO.