Reduce the Lora Sensor Power Consumption

In this project, we will learn how to reduce the Lora sensor power consumption, we aimed to make the Lora soil moisture sensor can be long-term operated.

1. Standby Current

①Default

②Sensor Power Off

③Microcontroller Sleep

④Lora Module Reset

2. Power Consumption per Communication

3. Power Consumption

① Default

④ Lora Module Reset

4. Arduino Code ④ Lora Module Reset

#include <SPI.h>
#include "RH_RF95.h"
#include <Adafruit_SleepyDog.h>
 
#include "I2C_AHT10.h"
#include <Wire.h>
AHT10 humiditySensor;
 
 
int sensorPin = A2;    // select the input pin for the potentiometer
int sensorValue = 0;  // variable to store the value coming from the sensor
int sensorPowerCtrlPin = 5;
 
void sensorPowerOn(void){
  digitalWrite(sensorPowerCtrlPin, HIGH);//Sensor power on
}
 
void sensorPowerOff(void){
  digitalWrite(sensorPowerCtrlPin, LOW);//Sensor power on
}
 
#define RFM95_CS 10
#define RFM95_RST 4
#define RFM95_INT 2
 
// Change to 434.0 or other frequency, must match RX's freq!
#define RF95_FREQ 915.0
 
// Singleton instance of the radio driver
RH_RF95 rf95(RFM95_CS, RFM95_INT);
 
void setup() {
  pinMode(RFM95_RST, OUTPUT);
  digitalWrite(RFM95_RST, LOW);
  delay(100);
  digitalWrite(RFM95_RST, HIGH);
 
  pinMode(sensorPowerCtrlPin, OUTPUT);
  sensorPowerOn();
  
  //while (!Serial);
  Serial.begin(115200);
  delay(100);
 
  Wire.begin(); //Join I2C bus
  //Check if the AHT10 will acknowledge
  if (humiditySensor.begin() == false){
    Serial.println("AHT10 not detected. Please check wiring. Freezing.");
    //while (1);
  }
  else
    Serial.println("AHT10 acknowledged.");
    
  Serial.println("Marduino LoRa TX Test!");
 
}
 
int16_t packetnum = 0;  // packet counter, we increment per xmission
float temperature=0.0;//
float humidity=0.0;
 
void loop(){
  setModule();
  
  sensorPowerOn();
  delay(100);
  sensorValue = analogRead(sensorPin);
  delay(200);
 
  if (humiditySensor.available() == true){
    //Get the new temperature and humidity value
    temperature = humiditySensor.getTemperature();
    humidity = humiditySensor.getHumidity();
 
    //Print the results
    Serial.print("Temperature: ");
    Serial.print(temperature, 2);
    Serial.print(" C\t");
    Serial.print("Humidity: ");
    Serial.print(humidity, 2);
    Serial.println("% RH");
 
    //sensor off
    sensorPowerOff();
 
    Serial.print(F("Moisture ADC : "));
    Serial.println(sensorValue);
  
    
    //Serial.print(F("Humidity: "));
    //Serial.print(humidity);
    //Serial.print(F("%  Temperature: "));
    //Serial.print(temperature);
    //Serial.println("Humidity is " + (String)humidity);
    //Serial.println("Temperature is " + (String)temperature);
  
    String message = "#"+(String)packetnum+" Humidity:"+(String)humidity+"% Temperature:"+(String)temperature+"C"+" ADC:"+(String)sensorValue;
    Serial.println(message);
    packetnum++;
    Serial.println("Transmit: Sending to rf95_server");
    
    // Send a message to rf95_server
  
    uint8_t radioPacket[message.length()+1];
    message.toCharArray(radioPacket, message.length()+1);
    
    radioPacket[message.length()+1]= '\0';
  
    Serial.println("Sending..."); delay(10);
    rf95.send((uint8_t *)radioPacket, message.length()+1);
    Serial.println("Waiting for packet to complete..."); delay(10);
    rf95.waitPacketSent();
    // Now wait for a reply
    uint8_t buf[RH_RF95_MAX_MESSAGE_LEN];
    uint8_t len = sizeof(buf);
  
    Serial.println("Waiting for reply..."); delay(10);
    if(rf95.waitAvailableTimeout(8000)){
      // Should be a reply message for us now  
      if (rf95.recv(buf, &len)){
        Serial.print("Got reply: ");
        Serial.println((char*)buf);
        Serial.print("RSSI: ");
        Serial.println(rf95.lastRssi(), DEC);  
      }
      else{
        Serial.println("Receive failed");
      }
    }
    else{
      Serial.println("No reply, is there a listener around?");
    }
 
    Serial.print("Sleep!!");
        
    // Lora module reset
    digitalWrite(RFM95_RST, LOW);
    delay(10);
    digitalWrite(RFM95_RST, HIGH);
    delay(10);
      
    //8sec sleep
    int sleepMS = Watchdog.sleep();
  }
}
 
void setModule(void){
  // manual reset
  digitalWrite(RFM95_RST, LOW);
  delay(10);
  digitalWrite(RFM95_RST, HIGH);
  delay(10);
 
  while(!rf95.init()) {
    Serial.println("LoRa radio init failed");
    while (1);
  }
  Serial.println("LoRa radio init OK!");
 
  //rf95.setModemConfig(Bw125Cr48Sf4096);
 
  //Defaults after init are 434.0MHz, modulation GFSK_Rb250Fd250, +13dbM
  if (!rf95.setFrequency(RF95_FREQ)) {
    Serial.println("setFrequency failed");
    while (1);
  }
  Serial.print("Set Freq to: ");
  Serial.println(RF95_FREQ);

  // Defaults after init are 434.0MHz, 13dBm, Bw = 125 kHz, Cr = 4/5, Sf = 128chips/symbol, CRC on

  // The default transmitter power is 13dBm, using PA_BOOST.
  // If you are using RFM95/96/97/98 modules which uses the PA_BOOST transmitter pin, then
  // you can set transmitter powers from 5 to 23 dBm:
  rf95.setTxPower(23, false);
}

5. Conclusion