Merge pull request #44 from NET-BYU/dht22_temp_correct

DHT22 temp correct
NET-BYU · Nov 17, 2020 · f32f661 · f32f661
2 parents b550d67 + c5ce247
commit f32f661
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Showing 2 changed files with 26 additions and 2 deletions.
diff --git a/lib/Sensors/src/Sensors.cpp b/lib/Sensors/src/Sensors.cpp
@@ -385,15 +385,31 @@ void Sensors::readDHT22(SensorPacket *packet) {
             temp = dht22.readTemperature(false, true);
             if (!isnan(temp)) {
                 packet->has_temperature = true;
-                packet->temperature = (int32_t)round(temp * 10);
+                if (abs(old_temp - temp) < MAX_TEMP_DIFF || temp_count >= COUNT_LIMIT ||
+                    old_temp == __FLT_MIN__) {
+                    packet->temperature = (int32_t)round(temp * 10);
+                    old_temp = temp;
+                    temp_count = 0;
+                } else {
+                    packet->temperature = (int32_t)round(old_temp * 10);
+                    temp_count++;
+                }
                 temp_valid = true;
             }
         }
         if (!hum_valid) {
             hum = dht22.readHumidity(true);
             if (!isnan(hum)) {
                 packet->has_humidity = true;
-                packet->humidity = (uint32_t)round(hum * 10);
+                if (abs(old_hum - hum) < MAX_HUM_DIFF || hum_count >= COUNT_LIMIT ||
+                    old_hum == __FLT_MIN__) {
+                    packet->humidity = (uint32_t)round(hum * 10);
+                    old_hum = hum;
+                    hum_count = 0;
+                } else {
+                    packet->humidity = (uint32_t)round(old_hum * 10);
+                    hum_count++;
+                }
                 hum_valid = true;
             }
         }

diff --git a/lib/Sensors/src/Sensors.h b/lib/Sensors/src/Sensors.h
@@ -10,6 +10,7 @@
 #include "TraceHeater.h"
 #include "adafruit-sht31.h"
 #include "sensor_packet.pb.h"
+#include <math.h>
 
 #define TEMP_HUM_I2C_ADDR 0x44 // Set to 0x45 for alternate i2c addr
 
@@ -125,8 +126,15 @@ class Sensors {
 // DHT22
 #define DHTPIN D2
 #define DHTTYPE DHT22
+#define MAX_TEMP_DIFF 15
+#define MAX_HUM_DIFF .15
+#define COUNT_LIMIT 5
     bool dht22Setup = true;
     DHT dht22;
+    float old_temp = __FLT_MIN__;
+    float old_hum = __FLT_MIN__;
+    int temp_count = 0;
+    int hum_count = 0;
 
 #ifdef PLATFORM_ID
     Logger sensorLog;