Cactus

๐ŸŒต Indoor WiFi-connected temperature and humidity sensor ๐Ÿถ

power LiPO
wireless WiFi
sensor Humidity
mcu ESP8266
battery life 1 month
bom items 36
bom cost USD $26.92
vendors 5
completed May 2019

Cactus Demo

temperature humidity wifi ifttt medium

Wakup every 6 hours to read the temperature and humidity


Details

Wakeup every 6 hours to read the temperature and humidity and send that value to IFTTT.

Serial console

Serial output from the firmware.

Code

Download code
#include <EEPROM.h>
#include <ESP8266WiFi.h>
#include <ESP8266WebServer.h>
#include <ESP8266mDNS.h>
#include <Ticker.h>
#include <math.h>
#include "Adafruit_Si7021.h"
#include "./web.h"

// Things to input
// Wakeup every 10,800,000,000 ยตs = 10800e6 = 10,800s = 3 hours
#define SLEEP_INTERVAL_DURATION  10800e6
#define SLEEP_DURATION_ENGLISH String("3 hours")
#define MAX_SLEEP_COUNT 2  // 3 hours * 2 times = 6 hours

// Options
#define DEBUG true
// Change to true if WiFi config need to be erased for a new SSID
// Change back to false and flash the firmware immediately
// TODO: Implement a factory reset button to erase all stored configurations
bool willEraseWiFiCredentials = false;

// Other constants
#define EN 2  // GPIO02 on ESP-01 module, D4 on nodeMCU WeMos, or on-board LED
#define LED 2
#define BATTERY_VOLT A0
#define USERBUTTON 12  // GPIO012 on ESP or D6 on WeMos
#define CURRENT_SLEEP_COUNT EEPROM.read(CURRENT_SLEEP_INTERVAL_ADDR)
#define IFTTT_KEY_LENGTH 22
#define CURRENT_SLEEP_INTERVAL_ADDR 30  // EEPROM add. to store sleep interval
#define MAX_WIFI_RECONNECT_INTERVAL 20  // WiFi will try to connect for 20s
#define MAX_AP_ON_MINUTES 5  // The AP mode will be on for 5 minutes

// WiFi
char ssid[50] = "secret";
char password[50] = "secret";
String AP_NamePrefix = "Cactus ";
const char WiFiAPPSK[] = "hutscape";
const char* DomainName = "cactus";  // set domain name domain.local

// LEDs and shift register
int dataPin = 13;  // pin D7 `GPIO13` on NodeMCU boards
int clockPin = 14;  // pin D5 `GPIO14` on NodeMCU boards
int latchPin = 15;  // pin D8 `GPIO15` on NodeMCU boards

struct SensorValues {
  float temperature;
  float humidity;
};

int userButtonValue = 1;
bool isAPWebServerRunning = false;
int apLoopCount = 0;
Ticker ticker;
SensorValues sensorValues;

const char* host = "maker.ifttt.com";
const int httpsPort = 443;
const int httpPort = 80;

// Get fingerprint of maker.ifttt.com
// echo | openssl s_client -connect maker.ifttt.com:443 |& openssl x509 -fingerprint -noout
const char fingerprint[] PROGMEM = "AA:75:CB:41:2E:D5:F9:97:FF:5D:A0:8B:7D:AC:12:21:08:4B:00:8C";

ESP8266WebServer server(80);
Adafruit_Si7021 sensor = Adafruit_Si7021();

void setup() {
  EEPROM.begin(512);
  Serial.begin(115200);

  disableWiFi();
  debugPrintln("");
  userButtonValue = digitalRead(USERBUTTON);

  debugPrintln("[INFO] Wakeup sleep count " + String(CURRENT_SLEEP_COUNT) + "/" + String(MAX_SLEEP_COUNT));

  if (willEraseWiFiCredentials) {
    eraseWiFiCredentials();
    debugPrintln("[INFO] Erasing WiFi credentials");
    debugPrintln("[INFO] Read empty WiFi SSID: " + WiFi.SSID());
  }

  if (!isCurrentSleepCountMax() && !hasUserPressedButton(userButtonValue)) {
    increaseSleepCount();
    debugPrintln("[INFO] Going into deep sleep for " + SLEEP_DURATION_ENGLISH);
    goToSleep();
    return;
  }

  initReadingBatteryVoltage();
  initTempHumiditySensor();
  resetSleepCount();
  sensorValues = readTempHumidity();

  if (hasUserPressedButton(userButtonValue)) {
    debugPrintln("[INFO] Wakeup on user button press!");
    initShiftRegister();
    displayHumidity(sensorValues.humidity);
  }

  enableWiFi();
  bool isConnectedToWiFi = connectToWiFi(true);
  if (isConnectedToWiFi) {
    debugPrintln("[INFO] Connected succesfully to WiFi SSID " + WiFi.SSID());
    debugPrintln("[INFO] WiFi connected! IP address: " + WiFi.localIP().toString());
  } else {
    debugPrintln("[ERROR] Connection to WiFi failed");
    debugPrintln("[INFO] Configuring access point");
    initAccessPoint();
    debugPrintln("[INFO] Started access point at IP " + WiFi.softAPIP().toString());

    bool hasMDNSStarted = MDNS.begin(DomainName, WiFi.softAPIP());
    if (!hasMDNSStarted) {
      debugPrintln("[ERROR] mDNS has failed to start");
    }

    startServer();
    debugPrintln("[INFO] WiFi is not configured!");
    debugPrintln("[INFO] Connect to SSID 'Cactus NNNN'");
    debugPrintln("[INFO] Go to http://cactus.local");

    // Start blinking LED to indicate AP mode
    pinMode(LED_BUILTIN, OUTPUT);
    ticker.attach(1, blink);
  }
}

void loop() {
  if (isAPWebServerRunning) {
    MDNS.update();
    server.handleClient();

    if (++apLoopCount > MAX_AP_ON_MINUTES*600) {
      debugPrintln("[INFO] Going into deep sleep for " + SLEEP_DURATION_ENGLISH);
      goToSleep();
    }
    delay(100);
  } else {
    ticker.detach();

    sendToIFTTT(sensorValues, getBatteryVoltage());
    debugPrintln("");
    debugPrintln("[INFO] Going into deep sleep after task for " + SLEEP_DURATION_ENGLISH);
    goToSleep();
  }
}

// Print functions
void debugPrintln(String s) {
  if (DEBUG) {
    Serial.println(s);
  }
}

void debugPrint(String s) {
  if (DEBUG) {
    Serial.print(s);
  }
}

// Sleep functions
bool isCurrentSleepCountMax() {
  return CURRENT_SLEEP_COUNT >= MAX_SLEEP_COUNT;
}

void increaseSleepCount() {
  EEPROM.write(CURRENT_SLEEP_INTERVAL_ADDR, CURRENT_SLEEP_COUNT + 1);
  EEPROM.commit();
}

void resetSleepCount() {
  EEPROM.write(CURRENT_SLEEP_INTERVAL_ADDR, 1);
  EEPROM.commit();
}

// EEPROM
String readKey() {
  String readStr;
  char readChar;

  for (int i = 0; i < IFTTT_KEY_LENGTH; ++i) {
    readChar = char(EEPROM.read(i));
    readStr += readChar;
  }

  return readStr;
}

String readEvent() {
  String word;
  char readChar;

  // IFTTT Event name is stored after the IFTTT Key in EEPROM
  int i = IFTTT_KEY_LENGTH;

  while (readChar != '\0') {
    readChar = char(EEPROM.read(i));
    delay(10);
    i++;

    if (readChar != '\0') {
      word += readChar;
    }
  }

  word[word.length() - 1] = '\0';
  return word;
}

void clearEEPROM() {
  EEPROM.begin(512);

  for (int i = 0; i < 512; i++) {
    EEPROM.write(i, 0);
  }

  EEPROM.commit();
}

void writeKey(String writeStr) {
  delay(10);

  for (int i = 0; i < writeStr.length(); ++i) {
    EEPROM.write(i, writeStr[i]);
  }

  EEPROM.commit();
}

void writeEvent(String eventName) {
  delay(10);

  int address = 0;
  int eventNameIndex = 0;
  int initialAddress = IFTTT_KEY_LENGTH;
  int finalAddress = IFTTT_KEY_LENGTH + eventName.length();

  for (address = initialAddress; address < finalAddress; ++address) {
    delay(10);

    EEPROM.write(address, eventName[eventNameIndex]);
    eventNameIndex++;
  }

  EEPROM.write(finalAddress, '\0');
  EEPROM.commit();
}

// Battery
float getBatteryVoltage() {
  unsigned int raw = 0;
  float volt = 0.0;
  float batteryVoltage = 0.0;

  // NOTE: Get 10 analog values and smoothen it
  for (int count = 0; count < 10; count++) {
    raw = analogRead(A0);
    volt = raw / 1023.0;
    volt *= 4.2;

    batteryVoltage += volt;
  }

  batteryVoltage /= 10;

  Serial.print("[INFO] Battery voltage is ");
  Serial.print(batteryVoltage);
  Serial.println("V");

  return volt;
}

// Sensor functions
bool hasUserPressedButton(int userButtonValue) {
  return userButtonValue == 0;
}

void blink() {
  int state = digitalRead(LED_BUILTIN);
  digitalWrite(LED_BUILTIN, !state);
}

void ledOFF() {
  digitalWrite(LED_BUILTIN, HIGH);
}

void initShiftRegister() {
  pinMode(latchPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(dataPin, OUTPUT);

  pinMode(EN, OUTPUT);
  digitalWrite(EN, LOW);
}

void initReadingBatteryVoltage() {
  pinMode(BATTERY_VOLT, INPUT);
}

void initTempHumiditySensor() {
  if (!sensor.begin()) {
    Serial.println("[ERROR] Did not find Si7021 sensor!");
    while (true) {}
  }
}

SensorValues readTempHumidity(void) {
  SensorValues sensorValues = { 0.0, 0.0 };

  // NOTE: Get 10 sensor values and smoothen it
  for (int count = 0; count < 10; count++) {
    sensorValues.temperature += sensor.readTemperature();
    sensorValues.humidity += sensor.readHumidity();
  }

  sensorValues.temperature /= 10;
  sensorValues.humidity /= 10;

  Serial.print("[INFO] Temperature: ");
  Serial.print(sensorValues.temperature);
  Serial.print(" C, Humidity: ");
  Serial.print(sensorValues.humidity);
  Serial.println(" RH%");

  return sensorValues;
}

void displayHumidity(float humidity) {
  int barHumidity = humidity/20;
  String sBar = "[INFO] Display Humidity in LED: " + String(barHumidity) + " LEDs";
  Serial.println(sBar);

  displayLED(pow(2, barHumidity) -1);

  delay(10000);  // display the humidity LEDs on-board for 10 seconds
}

void displayLED(int lednumber) {
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, lednumber);
  digitalWrite(latchPin, HIGH);
}

// Sleep and Wakup functions
void goToSleep() {
  ESP.deepSleep(SLEEP_INTERVAL_DURATION, WAKE_RF_DISABLED);
}

// WiFi functions
void eraseWiFiCredentials() {
  WiFi.disconnect(true);
  ESP.eraseConfig();
  willEraseWiFiCredentials = false;
}

void enableWiFi() {
  WiFi.forceSleepWake();  // wakeup WiFi modem
  delay(1);
}

void disableWiFi() {
  WiFi.mode(WIFI_OFF);
  WiFi.forceSleepBegin();
  delay(1);
}

bool connectToWiFi(bool useCredsFromFlash) {
  if (useCredsFromFlash) {
    WiFi.begin();
  } else {
    WiFi.mode(WIFI_STA);
    WiFi.begin(ssid, password);
  }

  int count = 0;
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);

    if (++count % 10 == 0) {
      debugPrintln(".");
    } else {
      debugPrint(".");
    }

    if (count >= MAX_WIFI_RECONNECT_INTERVAL) {
      if (count % 10 != 0) {
        debugPrintln("");
      }
      return false;
    }
  }

  if (count % 10 != 0) {
    debugPrintln("");
  }

  WiFi.setAutoConnect(true);
  WiFi.setAutoReconnect(true);
  return true;
}

void initAccessPoint() {
  WiFi.mode(WIFI_AP);
  WiFi.softAP(createAPName().c_str(), WiFiAPPSK);
}

String createAPName() {
  uint8_t mac[WL_MAC_ADDR_LENGTH];
  WiFi.softAPmacAddress(mac);
  String macID = String(mac[WL_MAC_ADDR_LENGTH - 2], HEX) +
                 String(mac[WL_MAC_ADDR_LENGTH - 1], HEX);
  macID.toUpperCase();
  return AP_NamePrefix + macID;
}

void startServer() {
  server.on("/", handleRoot);

  const char * headerkeys[] = {"User-Agent", "Cookie"};
  size_t headerkeyssize = sizeof(headerkeys)/sizeof(char*);

  server.collectHeaders(headerkeys, headerkeyssize);
  server.begin();

  isAPWebServerRunning = true;
}

void handleRoot() {
  if (server.hasArg("ssid") && server.hasArg("password") && server.hasArg("key") && server.hasArg("event")) {
    String receivedSSID = server.arg("ssid");

    debugPrintln("[INFO] WiFi SSID received: " + receivedSSID);
    receivedSSID.toCharArray(ssid, 50);

    debugPrintln("[INFO] WiFi password received");
    server.arg("password").toCharArray(password, 50);
    // Serial.println(server.arg("password"));

    clearEEPROM();

    debugPrintln("[INFO] IFTTT key received!");
    writeKey(server.arg("key"));
    // Serial.println(server.arg("key"));

    debugPrintln("[INFO] IFTTT event name received!");
    writeEvent(server.arg("event"));
    // Serial.println(server.arg("event"));

    returnSuccessPage();
    delay(1000);

    bool hasConectedToWifi = connectToWiFi(false);

    if (!hasConectedToWifi) {
      Serial.println("[ERROR] Cannot connect to WiFi after AP mode!");
      server.sendHeader("Location", "/");
      server.sendHeader("Cache-Control", "no-cache");
      server.sendHeader("Set-Cookie", "ESPSESSIONID=1");
      server.send(301);
      return;
    }

    debugPrintln("[INFO] Connected to WiFi after AP mode!");

    isAPWebServerRunning = false;
    return;
  }

  returnConfigPage();
}

void returnConfigPage() {
  server.send(200, "text/html", content);
}

void returnSuccessPage() {
  String content = "<html><body><h1>Received!</h1></body></html>";
  server.send(301, "text/html", content);
}

// Cloud
void sendToIFTTT(SensorValues sensorValues, float batteryVoltage) {
  Serial.println("[INFO] Sending IFTTT notification...");

  WiFiClientSecure client;
  client.setFingerprint(fingerprint);
  // Serial.println("[INFO] Setting fingerprint...");

  if (!client.connect(host, httpsPort)) {
    Serial.println("[ERROR] Connection failed");
    return;
  }

  Serial.println("[INFO] Client connected");

  String url = "/trigger/" + readEvent() + "/with/key/" + readKey();
  // Serial.print("URL: ");
  // Serial.println(url);

  char data[34];
  // TODO: Never use sprintf. Use snprintf instead.  [runtime/printf]
  sprintf(data, "value1=%03d&value2=%03d&value3=%2.1f", roundToInt(sensorValues.temperature), roundToInt(sensorValues.humidity), batteryVoltage);

  Serial.print("[INFO] Data sent: ");
  Serial.println(data);
  Serial.print("[INFO] Data size: ");
  Serial.println(sizeof(data));

  client.println(String("POST ") + url + " HTTP/1.1");
  client.println(String("Host: ") + host);
  client.println(String("Content-Type: application/x-www-form-urlencoded"));
  client.print(String("Content-Length: "));
  client.println(sizeof(data));
  client.println();
  client.println(data);

  Serial.println("[INFO] Client posted");

  unsigned long timeout = millis();
  while (client.available() == 0) {
    if (millis() - timeout > 20000) {
      Serial.println("[ERROR] Client Timeout!");
      client.stop();
      return;
    }
  }

  Serial.println("[INFO] Reply from client:");
  while (client.available()) {
    String line = client.readStringUntil('\r');
    Serial.print(line);
  }

  client.stop();
  return;
}

// Others
int roundToInt(float value) {
  return (int)round(value);
}

Makefile

BOARD?=esp8266com:esp8266:d1_mini
PORT?=/dev/cu.wchusbserial1410

.PHONY: default lint all flash clean

default: lint all flash clean

lint:
	cpplint --extensions=ino --filter=-legal/copyright,-readability/todo,-readability/casting,-runtime/int,-whitespace/line_length,-runtime/printf *.ino

all:
	arduino-cli compile --fqbn $(BOARD) ./

flash:
	arduino-cli upload -p $(PORT) --fqbn $(BOARD) ./

clean:
	rm -f .*.bin
	rm -f .*.elf

Photos

Cactus Demo Photo 1
Cactus Demo Photo 2