Add support to pH sensor (#410)

Author: user2684

.travis.yml

@@ -449,3 +449,9 @@ jobs:
        - sed -r -i 's/\/\/(#include <sensors\/SensorFPM10A.h>)/\1/' $SKETCH
        - eval $OTA_CONFIGURATION
        - eval $COMPILE
+    - name: "SensorPH"
+      script: 
+       - sed -r -i 's/\/\/(SensorPH .+)/\1/' $SKETCH
+       - sed -r -i 's/\/\/(#include <sensors\/SensorPH.h>)/\1/' $SKETCH
+       - eval $OTA_CONFIGURATION
+       - eval $COMPILE

README.md

@@ -143,7 +143,7 @@ SensorAPDS9960           | 1     | SparkFun RGB and Gesture Sensor
 SensorNeopixel           | 1     | Control a Neopixel LED                                                                            | https://github.com/adafruit/Adafruit_NeoPixel
 SensorSDS011             | 2     | SDS011 air quality sensor, return concentrations of 2.5 and 10 micrometer particles.              | https://github.com/ricki-z/SDS011
 SensorFPM10A             | 1     | FPM10A fingerprint sensor                                                                         | https://github.com/adafruit/Adafruit-Fingerprint-Sensor-Library
-
+SensorPH                 | 1     | PH ( SKU SEN161 ) sensor, measure the analog value from the amplifier module                      | -
 
 Those sensors requiring a pin to operate would take it as an argument in the constructor. 
 NodeManager automatically creates all the child_ids, assigning an incremental counter. If you need to set your own child_id, pass it as the last argument to the constructor
@@ -872,6 +872,16 @@ Each sensor class may expose additional methods.
 	bool getFingerprintIsValid();
 ~~~
 
+* SensorPH
+~~~c
+	// setting AnalogRefValue (default: 5.0)
+	void setVoltageRef(float value);
+	// setting the voltage value @ph = 7 (default: 2.52)
+	void setPH7Voltage(float value);
+	// setting the voltage value @ph = 4 (default: 3.04)
+    void setPH4Voltage(float value);
+~~~
+
 ### OTA Configuration
 
 When `NODEMANAGER_OTA_CONFIGURATION` is set to ON the API presented above can be also called remotely through `SensorConfiguration`, which is automatically added to NodeManager. SensorConfiguration exposes by default child id 200 that can be used to interact with the service by sending `V_CUSTOM` type of messages and commands within the payload. For each `REQ` message, the node will respond with a `SET` message if successful. 

examples/Template/Template.ino

@@ -343,6 +343,9 @@ NodeManager. Just uncomment the settings you need and the sensors you want to ad
 //#include <sensors/SensorFPM10A.h>
 //SensorFPM10A fpm10a(4,5);
 
+//#include <sensors/SensorPH.h>
+//SensorPH ph(A0);
+
 /***********************************
  * Main Sketch
  */

sensors/SensorPH.h

@@ -0,0 +1,90 @@
+/*
+* The MySensors Arduino library handles the wireless radio link and protocol
+* between your home built sensors/actuators and HA controller of choice.
+* The sensors forms a self healing radio network with optional repeaters. Each
+* repeater and gateway builds a routing tables in EEPROM which keeps track of the
+* network topology allowing messages to be routed to nodes.
+*
+* Created by Henrik Ekblad <[email protected]>
+* Copyright (C) 2013-2017 Sensnology AB
+* Full contributor list: https://github.com/mysensors/Arduino/graphs/contributors
+*
+* Documentation: http://www.mysensors.org
+* Support Forum: http://forum.mysensors.org
+*
+* This program is free software; you can redistribute it and/or
+* modify it under the terms of the GNU General Public License
+* version 2 as published by the Free Software Foundation.
+*/
+#ifndef SensorPH_h
+#define SensorPH_h
+
+/*
+* SensorPH: read the ph from an analog signal amplifier + ph probe
+*/
+
+class SensorPH: public Sensor {
+protected:
+	float _voltage_ref = 5.0;
+	float _ph7_voltage = 2.52;
+	float _ph4_voltage = 3.04;
+	float _ph_step;
+
+public:
+	SensorPH(int8_t pin, uint8_t child_id = 255): Sensor(pin) {
+		_name = "PH";
+		children.allocateBlocks(1);
+		new Child(this,FLOAT,nodeManager.getAvailableChildId(child_id),S_WATER_QUALITY,V_PH,_name);
+	};
+	
+	// setter/getter
+	void setVoltageRef(float value) {
+		_voltage_ref = value;
+	};
+	void setPH7Voltage(float value) {
+		_ph7_voltage = value;
+	};
+	void setPH4Voltage(float value) {
+		_ph4_voltage = value;
+	};
+
+	// what the sensor should do during setup
+	void onSetup() {
+		// set the pin as input
+		_ph_step = 1 - ( 1 + (_ph7_voltage - _ph4_voltage) / (7 - 4));
+		pinMode(_pin, INPUT);
+	};
+	
+	// what the sensor should do during loop
+	void onLoop(Child* child) {
+		int buf[10],temp;
+		// read the voltage across the amplifier and store 10 measurements
+		for (int i=0; i<10; i++) { 
+			float adc = analogRead(_pin);
+			// calculate the ph
+			double reading = _voltage_ref / 1024.0 * adc; 
+			float ph = 7 + ((_ph7_voltage - reading) / _ph_step);
+			buf[i]= ph * 1000;
+			delay(10);
+		}
+		// ordering : higher to lower values
+		for (int i=0; i<9; i++) {
+			for (int j=i+1; j<10; j++) {
+				if (buf[i] > buf[j]) {
+					temp = buf[i];
+					buf[i] = buf[j];
+					buf[j] = temp;
+				}
+			}
+		}
+		// discard the 2 highest and lowest walues and calculate mean of 6 remaining values
+		unsigned long int avgValue = 0;
+		float ph = 0; 
+		for (int i=2; i<8; i++) {
+			avgValue += buf[i];
+			ph = (float)avgValue/1000/6;  
+		}
+		child->setValue(ph);
+	};
+};
+#endif

sensors/SensorTemplate.h

@@ -34,7 +34,7 @@ class SensorExample: public Sensor {
 
 public:
 	// contructor, takes at least a NodeManager object. Calls its superclass
-	SensorExample(uint8_t child_id = 255): Sensor(child_id) {
+	SensorExample(int8_t pin, uint8_t child_id = 255): Sensor(pin) {
 		// set the sensor name. Useful when reviewing the logs and used as description of the child 
 		_name = "EXAMPLE";
 		// allocate a fixed number of blocks for the list containing the children