CO2 Sensor MH-Z19 Class (uses interrupt input as PWM input)

Dependencies:   mbed

Revision:
0:3c154d34f47e
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MH_Z19.cpp	Thu Aug 11 00:41:23 2016 +0000
@@ -0,0 +1,45 @@
+/* mbed MH-Z19 Library
+ * Copyright (c) 2016, zeus3110
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "MH_Z19.h"
+
+MH_Z19::MH_Z19(PinName p) : Port(p) {
+    Port.rise(this, &MH_Z19::rise);
+    Port.fall(this, &MH_Z19::fall);
+    OnWidth=2;
+    T.start();
+}
+
+int MH_Z19::ReadCO2PPM() {
+    
+    return ((CO2_MAX_PPM)*(OnWidth-2)/(PWM_CYCLE_MS-4));
+
+}
+    
+
+void MH_Z19::rise() {
+    T.reset();
+}
+
+void MH_Z19::fall() {
+    OnWidth=T.read_ms();
+}