HvacStation: post duty cycle to server

1 files changed, 54 insertions, 9 deletions

diff --git a/HvacStation/HvacStation.ino b/HvacStation/HvacStation.ino
index 02b2af9..7d687ac 100644
--- a/HvacStation/HvacStation.ino
+++ b/HvacStation/HvacStation.ino
@@ -2,6 +2,8 @@
 #include <HTTPClient.h>
 #include <PID_v1.h>
 
+#define nelem(arr) (sizeof(arr) / sizeof(arr[0]))
+
 enum {
 	SECOND = 1000,
 	PERIOD = 30*SECOND,
@@ -18,6 +20,7 @@ const char ssid[] = "Pixel_6504";
 const char password[] = "zj3av9sjev7ed8j";
 const char humidityUrl[] = "http://hvac.samanthony.xyz/humidity";
 const char targetUrl[] = "http://hvac.samanthony.xyz/target_humidity";
+const char dutyCycleUrl[] = "http://hvac.samanthony.xyz/duty_cycle";
 
 double pidInput, pidOutput, pidSetpoint;
 PID pid(&pidInput, &pidOutput, &pidSetpoint, P, I, D, DIRECT);
@@ -45,24 +48,33 @@ setup(void) {
 
 void
 loop(void) {
-	static unsigned long lastUpdate = 0; // Last time humidity and target were retrived from server.
 	static float humidity = 0.0; // Measured humidity of the building.
 	static float target = 0.0; // Target humidity.
+	static unsigned long lastUpdate = 0; // Last time the server was contacted.
+
+	pidInput = humidity;
+	pidSetpoint = target;
+	pid.Compute();
+	writeSolenoidPin(pidOutput);
 
 	unsigned long now = millis();
 	if (now - lastUpdate > PERIOD) {
-		// Retrieve measured and target humidity from the server.
-		if (get(humidityUrl, &humidity) != 0 || get(targetUrl, &target) != 0)
-			Serial.println("Failed to get humidity from server.");
 		lastUpdate = now;
+
+		if (get(humidityUrl, &humidity) != 0)
+			Serial.println("Failed to get humidity from server.");
+
+		if (get(targetUrl, &target) != 0)
+			Serial.println("Failed to get target from server.");
+
+		float dc = pidOutput / SOLENOID_WINDOW * 100.0;
+		if (postDuty(dc) != 0)
+			Serial.println("Failed to post duty cycle to server.");
+
 		Serial.printf("Measured humidity: %.2f%%\n", humidity);
 		Serial.printf("Target humidity: %.2f%%\n", target);
+		Serial.printf("Duty cycle: %.0f%%\n", dc);
 	}
-
-	pidInput = humidity;
-	pidSetpoint = target;
-	pid.Compute();
-	writeSolenoidPin(pidOutput);
 }
 
 // Make a GET request to the server and set *x to the float value that it responds with.
@@ -91,6 +103,39 @@ get(const char *url, float *x) {
 	return status;
 }
 
+// POST the duty cycle to the server. Return non-zero on error.
+int
+postDuty(float duty) {
+	static char url[512];
+	int n;
+
+	n = snprintf(url, nelem(url), "%s?%.0f", dutyCycleUrl, duty);
+	if (n >= nelem(url))
+		Serial.println("Duty cycle url string buffer overflow; truncating.");
+	return post(url);
+}
+
+// Make a POST request to the server. Return non-zero on error.
+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;
+}
+
 // Parse the value of str into *x. Returns non-zero on error.
 int
 parseFloat(const char *str, float *x) {