1.5.4

Backwards compatability added for  CalibrateZero();

Desync correction added on data mismatch.

Author: WifWaf

src/MHZ19.cpp

@@ -583,16 +583,8 @@ byte MHZ19::read(byte inBytes[MHZ19_DATA_LEN], Command_Type commandnumber)
             this->errorCode = RESULT_TIMEOUT;
 
             /* clear incomplete 9 byte values, limit is finite */
-            inBytes[1] = mySerial->available();
-            for(uint8_t x = 0; x < inBytes[1]; x++)
-            {
-                inBytes[0] = mySerial->read();
-                #if defined (ESP32) && (MHZ19_ERRORS) 
-                ESP_LOGW(TAG_MHZ19, "Clearing Byte: %d", inBytes[0]);  
-                #elif MHZ19_ERRORS
-                Serial.print("!Warning: Clearing Byte: "); Serial.println(inBytes[0]);
-                #endif     
-            }
+            cleanUp(mySerial->available());
+
             //return error condition
             return RESULT_TIMEOUT;
         }
@@ -612,7 +604,11 @@ byte MHZ19::read(byte inBytes[MHZ19_DATA_LEN], Command_Type commandnumber)
 
     /* construct error code */
     if (inBytes[0] != this->storage.constructedCommand[0] || inBytes[1] != this->storage.constructedCommand[2])
+    {
+       /* clear rx buffer for deysnc correction */
+        cleanUp(mySerial->available());
         this->errorCode = RESULT_MATCH;
+    }
 
     /* if error has been assigned */
     if (this->errorCode == RESULT_NULL)
@@ -625,6 +621,20 @@ byte MHZ19::read(byte inBytes[MHZ19_DATA_LEN], Command_Type commandnumber)
     return this->errorCode;
 }
 
+void MHZ19::cleanUp(uint8_t cnt)
+{
+    uint8_t eject = 0;
+    for(uint8_t x = 0; x < cnt; x++)
+    {
+        eject = mySerial->read();
+        #if defined (ESP32) && (MHZ19_ERRORS) 
+        ESP_LOGW(TAG_MHZ19, "Clearing Byte: %d", eject);  
+        #elif MHZ19_ERRORS
+        Serial.print("!Warning: Clearing Byte: "); Serial.println(eject);
+        #endif     
+    }
+}
+
 void MHZ19::handleResponse(Command_Type commandtype)
 {
     if (this->storage.constructedCommand[2] == Commands[RAWCO2])	// compare commands byte

src/MHZ19.h

@@ -110,6 +110,9 @@ class MHZ19
 	/* Calibrates "Zero" (Note: Zero refers to 400ppm for this sensor)*/
 	void calibrate();
 
+	/*  Calibrate Backwards compatability */
+	void inline calibrateZero(){ calibrate(); };
+
 	/* requests a reset */
 	void recoveryReset();
 
@@ -199,5 +202,7 @@ class MHZ19
 
 	/* converts bytes to integers according to *256 and + value */
 	unsigned int makeInt(byte high, byte low);
+
+	void cleanUp(uint8_t cnt);
 };
 #endif