LoRa FeatherWing IOX Tranceiver Mode Example Program

LoRaFW_IOX_TransceiverMode.ino

/*  LoRa FeatherWing IOX Tranceiver Mode Example Program
 *  By: Dan Watson | syncchannel.blogspot.com
 *  Date: 3-12-2016
 *  Version: 0.1 Initial Release
 *  
 *  Example Tranceiver Mode Program for the LoRa FeatherWing IOX for Adafruit Feather
 *  Tested with Feather M0, 32U4 and HUZZAH ESP8266
 *  
 *  This program configures the Feather as a LoRa receiver. It is intended as a companion
 *  to the LoRA FeatherWing Beacon Example Program, and can receive the beacon messages.
 *  It can also be modified to relay serial communications between Feather nodes, amongst
 *  other things.
 * 
 *  This program is adapted from the RFM95W_Nexus library created by Gerben den Hartog
 *  It has been adapted from his code to work specifically on Adafruit Feather with
 *  the LoRa FeatherWing. Credit is given to Gerben for is useful library and work!
 *  Check out his full github repo if you are interested in LoRaWAN.
 * 
 *  This program also uses the Adafruit MCP-23008 library, which can be downloaded in
 *  the Arduino Library Manager. See these pages for more info:
 *  https://github.com/adafruit/Adafruit-MCP23008-library
 *  https://www.adafruit.com/products/593
 * 
 */

// SPI is used for the RFM module. I2C is used for the MCP-23008.
#include <SPI.h>
#include <Wire.h>
#include "Adafruit_MCP23008.h"

// Define GPIO pin descriptions
#define LED   0     //13 for M0/32U4, 0 for HUZZAH ESP8266

// Also define the pin you selected for the MCP-23008 interrupt, if desired
// You don't need it when using the Adafruit library

// Define I/O expander connections to RFM module. These are hard wired.
#define DIO0        5
#define DIO1        6
#define DIO2        7
#define DIO3        3
#define DIO4        4
#define DIO5        0
#define CS          2
#define RFM_RESET   1

// Set this true to invert the LED outputs (for HUZZAH ESP8266) (optional)
#define LEDINVERT true

// Set frequency of RFM module
// Available frequencies depend on which RFM module you have
#define RFM_FREQ_MHZ 915000000

// Define the length of the user message payload in bytes
#define PACKAGE_LENGTH 10

// The Adafruit MCP-23008 library is very easy to use. To access a pin on the RFM module,
// use the standard digitalRead and digitalWrite commands with "iox." in front.
Adafruit_MCP23008 iox;

void setup()
{
  Serial.begin(9600);
  
  //Initialize SPI
  SPI.begin();
  SPI.beginTransaction(SPISettings(4000000,MSBFIRST,SPI_MODE0));

  iox.begin(); // Default address

  //Initialize I/O pins on MCP-23008
  iox.pinMode(DIO0,INPUT);
  iox.pinMode(DIO5,INPUT);
  iox.pinMode(CS,OUTPUT);

  // Initialize normal GPIO on the Feather
  pinMode(LED,OUTPUT);

  // Pull chip select high for now
  iox.digitalWrite(CS,HIGH);

  // Minimum of 100ms recommended to allow RFM module to start up
  delay(200);

  //Initialize the RFM module
  RFM_Init();

  // Flash LED on Feather to notify user that setup is complete
  for (int i = 0; i <= 3; i++)
  {
    digitalWrite(LED, HIGH^LEDINVERT);
    delay(100);
    digitalWrite(LED, LOW^LEDINVERT);
    delay(200);
  }
}

void loop() 
{
  //Check if the RFM has received a package
  if(iox.digitalRead(DIO0) == HIGH)
  {
    digitalWrite(LED, HIGH^LEDINVERT);
    
    //Get package from RFM
    unsigned char RFM_Package[PACKAGE_LENGTH];
    RFM_ReadPackage(RFM_Package);

    if (RFM_Package[0] == 0xD7 && RFM_Package[1] == 0xD7) // Valid message
    {
      //Send report over serial
      Serial.print("Got message from Node 0x");
      Serial.println(RFM_Package[2], HEX);

      Serial.print("Raw Message: [ ");
      for(int i = 0; i < PACKAGE_LENGTH; i++)
        {
          if (RFM_Package[i] < 0x10)
            Serial.print("0");
          Serial.print(RFM_Package[i], HEX);
          Serial.print(" ");
        }
      Serial.println("]");

      if (RFM_Package[3] == 0x01) // This is a temperature report
      {
        double temp = (RFM_Package[4] << 8) | RFM_Package[5];
        temp = (temp*3.22 - 400) / 19.5; // Temp in degrees C, equation for MCP-9701

        double batt = (RFM_Package[6] << 8) | RFM_Package[7];
        batt = batt*6.44; // *3.22 to convert to mV, *2 due to divider

        uint16_t messageCounter = (RFM_Package[8] << 8) | RFM_Package[9];

        Serial.print("Temp: ");
        Serial.print(temp);
        Serial.print("*C | Batt: ");
        Serial.print(batt / 1000);
        Serial.print("V | Msg Count: ");
        Serial.println(messageCounter);
      }
    } else {
      Serial.println("Invalid Message Received!");
    }
    
    Serial.println("");
    delay(50);
    digitalWrite(LED, LOW^LEDINVERT);
  }
}

/*
 * Function to initialize the RFM module.
 * It is highly recommended that you read the datasheet for the module, there are lots of
 * settings you can adjust to improve the wireless link parameters for your specific usage
 * http://www.hoperf.com/upload/rf/RFM95_96_97_98W.pdf
 */
void RFM_Init()
{
  //Set RFM module in sleep mode to change to LoRa mode
  RFM_Write(0x01,0x00);

  //Set LoRa mode
  RFM_Write(0x01,0x80);

  //Set RFM module in standby mode to change more settings
  RFM_Write(0x01,0x81);
  
  while(iox.digitalRead(DIO5) == LOW)
  {
    //Wait for mode ready
  }

  // Set carrier frequency
  // RFM_FREQ_MHZ / 61.035 Hz = 3 byte value to load
  unsigned long freqHolder = RFM_FREQ_MHZ / 61.035; // round down
  uint8_t freqLSB = freqHolder;
  uint8_t freq2B = (freqHolder >> 8);
  uint8_t freqMSB = (freqHolder >> 16);
  
  RFM_Write(0x06,freqMSB);
  RFM_Write(0x07,freq2B);
  RFM_Write(0x08,freqLSB);

  //Set maximum transmit power settings
  RFM_Write(0x09,0xFF);

  //Set bandwith 250 kHz, Coding rate = 4/8, Implicit header mode
  RFM_Write(0x1D,0x89);

  //Spreading factor 11, PayloadCRC on
  RFM_Write(0x1E,0xB4);

  //*NOTE: If you decide to change to Spreading Factor 6, you also need to set the following
  //*two registers by uncommenting these lines
  //RFM_Write(0x31,0xC5);
  //RFM_Write(0x37,0x0C);

  //Preamble length 0x0018 + 4 = 28
  RFM_Write(0x20,0x00);
  RFM_Write(0x21,0x18);

  //Payload length
  RFM_Write(0x22,PACKAGE_LENGTH);

  //Set RFM in continues receive
  RFM_Write(0x01,0x85);
  
  while(iox.digitalRead(DIO5) == LOW)
  {
    //Wait for mode ready
  }
}

/* This function is used to read a value from a specific register of the RFM module
*  Arguments: RFM_Adress  Adress of the register to read
*  Return: The value of the register is returned
*/
unsigned char RFM_Read(unsigned char RFM_Address)
{
  unsigned char RFM_Data;

  //Set CS pin low to start SPI communication
  iox.digitalWrite(CS,LOW);

  //Send Address
  SPI.transfer(RFM_Address);
  
  //Send 0x00 to receive the answer from the RFM
  RFM_Data = SPI.transfer(0x00);

  //Set CS high to end communication
  iox.digitalWrite(CS,HIGH);

  //Return received data
  return RFM_Data;
}

/* This function is used to write a value to a specific register of the RFM module
 * Arguments: RFM_Adress  Adress of the register to be written
 *            RFM_Data    Data that will be written
 */
void RFM_Write(unsigned char RFM_Address, unsigned char RFM_Data)
{
  //Set CS pin low to start communication
  iox.digitalWrite(CS,LOW);

  //Send Addres with MSB 1 to make it a write command
  SPI.transfer(RFM_Address | 0x80);
  
  //Send Data
  SPI.transfer(RFM_Data);

  //Set CS pin high to end communication
  iox.digitalWrite(CS,HIGH);
}

/* This function is used to send a message payload
 * Arguments: *RFM_Package Pointer to the array with the data to send
 */
void RFM_SendPackage(unsigned char *RFM_Package)
{
  //Switch RFM to standby
  RFM_Write(0x01,0x81);

  while(iox.digitalRead(DIO5) == LOW)
  {
    //Wait for mode ready
  }

  //Set SPI pointer to Tx base address
  RFM_Write(0x0D,0x80);

  //Switch DIO to TxDone
  RFM_Write(0x40,0x40);

  //Write payload in to the FIFO
  for(int i = 0; i < PACKAGE_LENGTH; i++)
  {
    RFM_Write(0x00,*RFM_Package);
    RFM_Package++;
  }

  //Switch RFM to TX
  RFM_Write(0x01,0x83);

  while(iox.digitalRead(DIO0) == LOW)
  {
    //Wait for Tx Done
  }

  //Clear interrupt
  RFM_Write(0x12,0x08);

  //Set DIO0 to RxDone
  RFM_Write(0x40,0x00);

   //Set RFM in continues receive
  RFM_Write(0x01,0x85);
  
  while(iox.digitalRead(DIO5) == LOW)
  {
    //Wait for mode ready
  }    
}

/* This function is used to receive a message/payload from the RFM module
 * Arguments: *RFM_Package  Pointer to the array with the data to send
*/
void RFM_ReadPackage(unsigned char *RFM_Package)
{
  unsigned char RFM_Interrupt;
  unsigned char RFM_PackageLocation;

  //Get interrupt register
  RFM_Interrupt = RFM_Read(0x12);

  //Switch RFM to Standby
  RFM_Write(0x01,0x81);
  
  while(iox.digitalRead(DIO5) == LOW)
  {
    //Wait for mode ready
  }

  //Clear interrupt register
  RFM_Write(0x12,0x60);

  //Get package location
  RFM_PackageLocation = RFM_Read(0x10);

  //Set SPI pointer to Packagelocation
  RFM_Write(0x0D,RFM_PackageLocation);

  //Get message
  for(int i = 0; i < PACKAGE_LENGTH; i++)
  {
    *RFM_Package = RFM_Read(0x00);
    RFM_Package++;
  }

  //Switch RFM to receive
  RFM_Write(0x01,0x85);
  
  while(iox.digitalRead(DIO5) == LOW)
  {
    //Wait for mode ready
  }    
}