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#include <WiFi.h>
#include <HTTPClient.h>
#include <DHT.h>
#define nelem(arr) (sizeof(arr) / sizeof(arr[0]))
enum pins {
DHT_PIN = 21,
UP_BTN = 16,
DOWN_BTN = 17,
};
enum {
SECOND = 1000,
PERIOD = 30*SECOND, // Humidity sample period.
DEBOUNCE = 50, // Button debounce time.
// Wait this long before updating the server when target humidity is changed.
// Avoids spamming requests when button is pressed repeatedly.
DEADTIME = 1000,
};
const char ssid[] = "Pixel_6504";
const char password[] = "zj3av9sjev7ed8j";
const char domain[] = "hvac.samanthony.xyz";
const char humidityPath[] = "/humidity";
const char targetHumidityPath[] = "/target_humidity";
const char roomID[] = "SNbeEcs7XVWMEvjeEYgwZnp9XYjToVhh";
const float defaultTarget = 35.0; // Default target humidity.
const float minTarget = 0.0; // Minimum target humidity.
const float maxTarget = 100.0; // Maximum target humidity.
const float incTarget = 0.5; // Target humidity increment from button press.
DHT dht(DHT_PIN, DHT11); // Humidity sensor.
void
setup(void) {
pinMode(UP_BTN, INPUT);
pinMode(DOWN_BTN, INPUT);
Serial.begin(9600);
while (!Serial) {}
WiFi.begin(ssid, password);
Serial.print("Connecting to WiFi...");
while (WiFi.status() != WL_CONNECTED) {
Serial.print(".");
delay(500);
}
Serial.println(" connected.");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
Serial.print("Initializing DHT11 humidity sensor...");
delay(1*SECOND); /* Let sensor stabilize after power-on. */
dht.begin();
Serial.println(" done.");
}
void
loop(void) {
static unsigned long lastSample = 0; // Last time humidity was measured.
static float targetHumidity = defaultTarget;
static bool targetDirty = true; // True when target humidity is changed.
static unsigned long targetDeadtimeStart; // Don't spam requests when button pressed repeatedly.
unsigned long now = millis();
// Measure humidity.
if (now - lastSample > PERIOD) {
measureHumidity();
lastSample = now;
}
// Update target humidity if buttons are pressed.
if (upButton() && targetHumidity+incTarget <= maxTarget) {
targetHumidity += incTarget;
targetDirty = true;
targetDeadtimeStart = now;
Serial.printf("Up. Target humidity: %.2f%%\n", targetHumidity);
} else if (downButton() && targetHumidity-incTarget >= minTarget) {
targetHumidity -= incTarget;
targetDirty = true;
targetDeadtimeStart = now;
Serial.printf("Down. Target humidity: %.2f%%\n", targetHumidity);
}
// Send updated target humidity to server.
if (targetDirty && now-targetDeadtimeStart > DEADTIME) {
if (setTarget(targetHumidity) == 0) {
targetDirty = false; // Success.
} else {
Serial.println("Failed to send target humidity to server.");
targetDeadtimeStart = now; // Delay retry.
}
}
}
// Measure the humidity and send it to the server.
void
measureHumidity(void) {
// Measure humidity.
float humidity = dht.readHumidity();
Serial.printf("Humidity: %.2f %% RH\n", humidity);
// Send measured humidity to server.
const char *url = humidityUrl(humidity);
if (post(url) != 0)
Serial.println("Failed to send humidity to server.");
}
// Set the target humidity on the server. Return non-zero on error.
int
setTarget(float target) {
const char *url = targetUrl(target);
return post(url);
}
// Format the humidity URL string.
char *
humidityUrl(float humidity) {
static char query[256];
int n;
n = snprintf(query, nelem(query), "room=%s&humidity=%.2f", roomID, humidity);
if (n >= nelem(query))
Serial.println("Humidity query string buffer overflow; truncating.");
return url(domain, humidityPath, query);
}
// Format the target humidity URL string.
char *
targetUrl(float target) {
static char query[256];
int n;
n = snprintf(query, nelem(query), "%.2f", target);
if (n >= nelem(query))
Serial.println("Target query string buffer overflow; truncating.");
return url(domain, targetHumidityPath, query);
}
// Make a POST request to the server.
int
post(const char *url) {
if (WiFi.status() != WL_CONNECTED) {
Serial.println("WiFi not connected.");
return 1;
}
WiFiClient client;
HTTPClient http;
Serial.printf("POST %s...\n", url);
http.begin(client, url);
int responseCode = http.POST("");
http.end();
Serial.printf("HTTP response code: %d\n", responseCode);
if (responseCode != HTTP_CODE_OK)
return 1;
return 0;
}
// Format the url string. Query should not include the '?'.
char *
url(const char *domain, const char *path, const char *query) {
static char buf[512];
int n;
n = snprintf(buf, nelem(buf), "http://%s%s?%s", domain, path, query);
if (n >= nelem(buf))
Serial.println("URL string buffer overflow; truncating.");
return buf;
}
// Return true if the UP button was pressed.
bool
upButton(void) {
static bool state = LOW;
static unsigned long lastEvent = 0;
return buttonPressed(UP_BTN, &state, &lastEvent);
}
// Return true if the DOWN button was pressed.
bool
downButton(void) {
static bool state = LOW;
static unsigned long lastEvent = 0;
return buttonPressed(DOWN_BTN, &state, &lastEvent);
}
// Return true if the button connected to the specified pin was pressed.
bool
buttonPressed(int pin, bool *lastState, unsigned long *lastEvent) {
unsigned long now = millis();
if (digitalRead(pin)) {
if (*lastState == LOW && now-*lastEvent > DEBOUNCE) {
// Rising event.
*lastState = HIGH;
*lastEvent = now;
return true;
}
} else if (now-*lastEvent > DEBOUNCE) {
// Falling event.
*lastState = LOW;
*lastEvent = now;
}
return false;
}
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