Add an OLED

Now that we've got our Feather M0 connecting to The Things Network, we'll add a FeatherWing OLED to view the active connection with The Things Network and the sensor measurements.

Adafruit FeatherWing OLED - 128x32 OLED Add-on For Feather

PRODUCT ID: 2900
A Feather board without ambition is a Feather board without FeatherWings! This is the FeatherWing OLED: it adds a 128x32 monochrome OLED plus 3 user buttons to...
$14.95
IN STOCK

Snap the FeatherWing onto your Feather, navigate to the FeatherWing OLED Arduino Setup guide, and follow the instructions to set up and test the OLED. Once you verify that the FeatherWing OLED works, copy and paste the code below into a new sketch.

Make sure to re-enter your unique device identifiers before compiling and uploading the sketch.

Code

/*******************************************************************************
 * The Things Network - Sensor Data Example with OLED
 * 
 * Example of sending a valid LoRaWAN packet with DHT22 temperature and
 * humidity data to The Things Networ using a Feather M0 LoRa.
 * 
 * Learn Guide: https://learn.adafruit.com/the-things-network-for-feather
 * 
 * Copyright (c) 2015 Thomas Telkamp and Matthijs Kooijman
 * Copyright (c) 2018 Terry Moore, MCCI
 * Copyright (c) 2018 Brent Rubell, Adafruit Industries
 * 
 * Permission is hereby granted, free of charge, to anyone
 * obtaining a copy of this document and accompanying files,
 * to do whatever they want with them without any restriction,
 * including, but not limited to, copying, modification and redistribution.
 * NO WARRANTY OF ANY KIND IS PROVIDED.
 *******************************************************************************/
#include <lmic.h>
#include <hal/hal.h>
#include <SPI.h>

// include the DHT22 Sensor Library
#include "DHT.h"

// include the FeatherWing OLED library
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// DHT digital pin and sensor type
#define DHTPIN 10
#define DHTTYPE DHT22

Adafruit_SSD1306 display = Adafruit_SSD1306();

#if (SSD1306_LCDHEIGHT != 32)
 #error("Height incorrect, please fix Adafruit_SSD1306.h!");
#endif

//
// For normal use, we require that you edit the sketch to replace FILLMEIN
// with values assigned by the TTN console. However, for regression tests,
// we want to be able to compile these scripts. The regression tests define
// COMPILE_REGRESSION_TEST, and in that case we define FILLMEIN to a non-
// working but innocuous value.
//
#ifdef COMPILE_REGRESSION_TEST
#define FILLMEIN 0
#else
#warning "You must replace the values marked FILLMEIN with real values from the TTN control panel!"
#define FILLMEIN (#dont edit this, edit the lines that use FILLMEIN)
#endif

// This EUI must be in little-endian format, so least-significant-byte
// first. When copying an EUI from ttnctl output, this means to reverse
// the bytes. For TTN issued EUIs the last bytes should be 0xD5, 0xB3,
// 0x70.
static const u1_t PROGMEM APPEUI[8] = { FILLMEIN };
void os_getArtEui (u1_t* buf) { memcpy_P(buf, APPEUI, 8);}

// This should also be in little endian format, see above.
static const u1_t PROGMEM DEVEUI[8] = { FILLMEIN };
void os_getDevEui (u1_t* buf) { memcpy_P(buf, DEVEUI, 8);}

// This key should be in big endian format (or, since it is not really a
// number but a block of memory, endianness does not really apply). In
// practice, a key taken from the TTN console can be copied as-is.
static const u1_t PROGMEM APPKEY[16] = { FILLMEIN };
void os_getDevKey (u1_t* buf) {  memcpy_P(buf, APPKEY, 16);}

// payload to send to TTN gateway
static uint8_t payload[5];
static osjob_t sendjob;

// Schedule TX every this many seconds (might become longer due to duty
// cycle limitations).
const unsigned TX_INTERVAL = 10;

// dht
float temperature;
float rHumidity;

// Pin mapping for Adafruit Feather M0 LoRa
const lmic_pinmap lmic_pins = {
    .nss = 8,
    .rxtx = LMIC_UNUSED_PIN,
    .rst = 4,
    .dio = {3, 6, LMIC_UNUSED_PIN},
    .rxtx_rx_active = 0,
    .rssi_cal = 8,              // LBT cal for the Adafruit Feather M0 LoRa, in dB
    .spi_freq = 8000000,
};

// init. DHT
DHT dht(DHTPIN, DHTTYPE);

void onEvent (ev_t ev) {
    Serial.print(os_getTime());
    Serial.print(": ");
    switch(ev) {
        case EV_SCAN_TIMEOUT:
            Serial.println(F("EV_SCAN_TIMEOUT"));
            break;
        case EV_BEACON_FOUND:
            Serial.println(F("EV_BEACON_FOUND"));
            break;
        case EV_BEACON_MISSED:
            Serial.println(F("EV_BEACON_MISSED"));
            break;
        case EV_BEACON_TRACKED:
            Serial.println(F("EV_BEACON_TRACKED"));
            break;
        case EV_JOINING:
            display.print("TTN: Joining...");
            display.display();
            Serial.println(F("EV_JOINING"));
            break;
        case EV_JOINED:
            display.clearDisplay();
            display.display();
            display.setCursor(0, 0);
            display.println("TTN: Connected");
            display.display();
            Serial.println(F("EV_JOINED"));
            {
              u4_t netid = 0;
              devaddr_t devaddr = 0;
              u1_t nwkKey[16];
              u1_t artKey[16];
              LMIC_getSessionKeys(&netid, &devaddr, nwkKey, artKey);
              Serial.print("netid: ");
              Serial.println(netid, DEC);
              Serial.print("devaddr: ");
              Serial.println(devaddr, HEX);
              Serial.print("artKey: ");
              for (int i=0; i<sizeof(artKey); ++i) {
                if (i != 0)
                  Serial.print("-");
                Serial.print(artKey[i], HEX);
              }
              Serial.println("");
              Serial.print("nwkKey: ");
              for (int i=0; i<sizeof(nwkKey); ++i) {
                      if (i != 0)
                              Serial.print("-");
                      Serial.print(nwkKey[i], HEX);
              }
              Serial.println("");
            }
            // Disable link check validation (automatically enabled
            // during join, but because slow data rates change max TX
      // size, we don't use it in this example.
            LMIC_setLinkCheckMode(0);
            break;
        /*
        || This event is defined but not used in the code. No
        || point in wasting codespace on it.
        ||
        || case EV_RFU1:
        ||     Serial.println(F("EV_RFU1"));
        ||     break;
        */
        case EV_JOIN_FAILED:
            Serial.println(F("EV_JOIN_FAILED"));
            break;
        case EV_REJOIN_FAILED:
            Serial.println(F("EV_REJOIN_FAILED"));
            break;
            break;
        case EV_TXCOMPLETE:
            display.clearDisplay();
            display.display();
            display.setCursor(0, 0);
            display.println("TTN: Connected");
            display.display();
            display.setCursor(0, 20);
            display.println("* Sent!");
            display.display();   
            Serial.println(F("EV_TXCOMPLETE (includes waiting for RX windows)"));
            if (LMIC.txrxFlags & TXRX_ACK)
              Serial.println(F("Received ack"));
            if (LMIC.dataLen) {
              Serial.println(F("Received "));
              Serial.println(LMIC.dataLen);
              Serial.println(F(" bytes of payload"));
            }
            // Schedule next transmission
            os_setTimedCallback(&sendjob, os_getTime()+sec2osticks(TX_INTERVAL), do_send);
            break;
        case EV_LOST_TSYNC:
            Serial.println(F("EV_LOST_TSYNC"));
            break;
        case EV_RESET:
            Serial.println(F("EV_RESET"));
            break;
        case EV_RXCOMPLETE:
            // data received in ping slot
            Serial.println(F("EV_RXCOMPLETE"));
            break;
        case EV_LINK_DEAD:
            Serial.println(F("EV_LINK_DEAD"));
            break;
        case EV_LINK_ALIVE:
            Serial.println(F("EV_LINK_ALIVE"));
            break;
        /*
        || This event is defined but not used in the code. No
        || point in wasting codespace on it.
        ||
        || case EV_SCAN_FOUND:
        ||    Serial.println(F("EV_SCAN_FOUND"));
        ||    break;
        */
        case EV_TXSTART:
            display.clearDisplay();
            display.display();
            display.setCursor(0, 0);
            display.println("TTN: Connected");
            display.setCursor(0, 10);
            display.println("* Sending");
            display.setCursor(0, 25);
            display.print("Temp: ");display.print(temperature*100);display.print(" C, ");
            display.print("RH%: ");display.print(rHumidity*100);
            display.display();
            Serial.println(F("EV_TXSTART"));
            break;
        default:
            Serial.print(F("Unknown event: "));
            Serial.println((unsigned) ev);
            break;
    }
}

void do_send(osjob_t* j){
    // Check if there is not a current TX/RX job running
    if (LMIC.opmode & OP_TXRXPEND) {
        Serial.println(F("OP_TXRXPEND, not sending"));
    } else {
        // read the temperature from the DHT22
        temperature = dht.readTemperature();
        Serial.print("Temperature: "); Serial.print(temperature);
        Serial.println(" *C");
        // adjust for the f2sflt16 range (-1 to 1)
        temperature = temperature / 100; 

        // read the humidity from the DHT22
        rHumidity = dht.readHumidity();
        Serial.print("%RH ");
        Serial.println(rHumidity);
        // adjust for the f2sflt16 range (-1 to 1)
        rHumidity = rHumidity / 100;
        
        // float -> int
        // note: this uses the sflt16 datum (https://github.com/mcci-catena/arduino-lmic#sflt16)
        uint16_t payloadTemp = LMIC_f2sflt16(temperature);
        // int -> bytes
        byte tempLow = lowByte(payloadTemp);
        byte tempHigh = highByte(payloadTemp);
        // place the bytes into the payload
        payload[0] = tempLow;
        payload[1] = tempHigh;

        // float -> int
        uint16_t payloadHumid = LMIC_f2sflt16(rHumidity);
        // int -> bytes
        byte humidLow = lowByte(payloadHumid);
        byte humidHigh = highByte(payloadHumid);
        payload[2] = humidLow;
        payload[3] = humidHigh;

        // prepare upstream data transmission at the next possible time.
        // transmit on port 1 (the first parameter); you can use any value from 1 to 223 (others are reserved).
        // don't request an ack (the last parameter, if not zero, requests an ack from the network).
        // Remember, acks consume a lot of network resources; don't ask for an ack unless you really need it.
        LMIC_setTxData2(1, payload, sizeof(payload)-1, 0);
        Serial.println(F("EV_TXSTART"));
    }
    // Next TX is scheduled after TX_COMPLETE event.
}

void setup() {
    delay(5000);
    while (! Serial);
    Serial.begin(9600);
    Serial.println(F("Starting"));

    dht.begin();
    // by default, we'll generate the high voltage from the 3.3v line internally! (neat!)
    display.begin(SSD1306_SWITCHCAPVCC, 0x3C);  // initialize with the I2C addr 0x3C (for the 128x32)
    Serial.println("OLED and DHT init'd");

    // Show image buffer on the display hardware.
    // Since the buffer is intialized with an Adafruit splashscreen
    // internally, this will display the splashscreen.
    display.display();
    delay(1000);
   
    // Clear the buffer.
    display.clearDisplay();
    display.display();

    // set text display size/location
    display.setTextSize(1);
    display.setTextColor(WHITE);
    display.setCursor(0,0);

    // LMIC init
    os_init();
    // Reset the MAC state. Session and pending data transfers will be discarded.
    LMIC_reset();
    // Disable link-check mode and ADR, because ADR tends to complicate testing.
    LMIC_setLinkCheckMode(0);
    // Set the data rate to Spreading Factor 7.  This is the fastest supported rate for 125 kHz channels, and it
    // minimizes air time and battery power. Set the transmission power to 14 dBi (25 mW).
    LMIC_setDrTxpow(DR_SF7,14);
    // in the US, with TTN, it saves join time if we start on subband 1 (channels 8-15). This will
    // get overridden after the join by parameters from the network. If working with other
    // networks or in other regions, this will need to be changed.
    LMIC_selectSubBand(1);

    // Start job (sending automatically starts OTAA too)
    do_send(&sendjob);
}

void loop() {
  // we call the LMIC's runloop processor. This will cause things to happen based on events and time. One
  // of the things that will happen is callbacks for transmission complete or received messages. We also
  // use this loop to queue periodic data transmissions.  You can put other things here in the `loop()` routine,
  // but beware that LoRaWAN timing is pretty tight, so if you do more than a few milliseconds of work, you
  // will want to call `os_runloop_once()` every so often, to keep the radio running.
  os_runloop_once();
}
This guide was first published on Sep 21, 2018. It was last updated on Sep 21, 2018. This page (Add an OLED) was last updated on Aug 17, 2019.