lora.cpp File Reference

#include "lora.h"
#include <RHReliableDatagram.h>
#include <SPI.h>
#include <RH_RF95.h>
#include <ArduinoJson.h>
#include <ftoa.h>

Go to the source code of this file.

Functions
RH_RF95	rf95 (RFM95_CS, RFM95_INT)
static RHReliableDatagram	manager (rf95, CLIENT_ADDRESS)
void	lora_init (void)
	Initialize the LoRa radio. More...
void	build_msg (float flow, char *weight, float temp, float maxtemp)
	Builds a JSON string to send over LoRa. More...
void	send_msg (void)
	Sends a LoRa packet to the base station. More...

Variables
static int16_t	packetnum = 0
static char	radiopacket [RH_RF95_MAX_MESSAGE_LEN]
static uint8_t	packet_len

Function Documentation

build_msg()

void build_msg	(	float	flow,
		char *	weight,
		float	temp,
		float	maxtemp
	)

Builds a JSON string to send over LoRa.

Builds a JSON string containing sapflow, weight, temperature, time, and tree ID. The string is stored in a global variable to be read by send_msg()

Parameters

flow	The calculated sapflow
weight	The text received from the scale. Use "0" if scale is not connected.
temp	The baseline temperature of the tree
time	The date and time from the Real-Time Clock

Definition at line 58 of file lora.cpp.

{
  Serial.print("Building message...");
  const int capacity=JSON_OBJECT_SIZE(10);
  StaticJsonDocument<capacity>doc;
  char str1[15];
  char str2[15];
  char str3[15];
  char * tstring = rtc_ds.now().text();
  tstring += 11; //< skip the date, just use the time
  ftoa(flow, str1);
  ftoa(temp, str3);
  ftoa(maxtemp, str2);
  doc["flow"].set(str1);
  doc["weight"].set("0");
  doc["temp"].set(str3);
  doc["maxtemp"].set(str2);
  doc["id"].set("0");
  doc["time"].set(tstring);
  packet_len = serializeJson(doc,radiopacket);
  Serial.println(radiopacket);
  radiopacket[packet_len] = 0;
}

lora_init()

void lora_init

(

void

)

Initialize the LoRa radio.

This function turns on the radio, sets the frequency, and prepares it for use. It does not take any parameters.

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:

Definition at line 17 of file lora.cpp.

{
  digitalWrite(RFM95_CS, LOW); //< enable LoRa
  pinMode(RFM95_RST, OUTPUT);
  digitalWrite(RFM95_RST, HIGH);
 
 
  // manual reset
  digitalWrite(RFM95_RST, LOW);
  delay(10);
  digitalWrite(RFM95_RST, HIGH);
  delay(10);
 
  while (!manager.init()) {
    Serial.println("LoRa radio init failed");
    Serial.println("Uncomment '#define SERIAL_DEBUG' in RH_RF95.cpp for detailed debug info");
    while (1);
  }
  Serial.println("LoRa radio init OK!");
 
  // 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);
  
  rf95.setTxPower(23, false);
  digitalWrite(RFM95_CS, HIGH); //< disable LoRa
}

send_msg()

void send_msg

(

void

)

Sends a LoRa packet to the base station.

Sends the string made by build_json() to the base station over LoRa. Calling this function without first calling build_msg() produces undefined behavior.

Definition at line 83 of file lora.cpp.

{
  digitalWrite(RFM95_CS, LOW); //< enable LoRa
  Serial.println("Transmitting..."); //< Send a message to rf95_server
  // Send a message to manager_server
  if (manager.sendtoWait((uint8_t *)radiopacket, packet_len, SERVER_ADDRESS))
  {
    // Now wait for a reply from the server
    uint8_t from;   
    if (manager.recvfromAckTimeout((uint8_t *)radiopacket, &packet_len, 2000, &from))
    {
      Serial.print("got reply from : 0x");
      Serial.print(from, HEX);
      Serial.print(": ");
      Serial.println(radiopacket);
      Serial.print("RSSI: ");
      Serial.println(rf95.lastRssi(), DEC);
    }
    else
    {
      Serial.println("No reply, is server running?");
    }
  }
  else
    Serial.println("sendtoWait failed");
 
  digitalWrite(RFM95_CS, HIGH); //< disable LoRa
}