From 14232ec7e87035ed02b23fc4189baff1224e6381 Mon Sep 17 00:00:00 2001
From: Sasa Karanovic <sasa@karanovic.ca>
Date: Wed, 14 Apr 2021 02:21:25 -0400
Subject: [PATCH] Initial commit.

---
 .../Firmware/CentralUnit/CentralUnit.ino      | 197 +++++++++
 .../Firmware/CentralUnit/CentralUnit_cfg.h    |  13 +
 .../Firmware/CentralUnit/PlantSystem.h        |  43 ++
 .../CentralUnit/PlantSystem_MainLogic.ino     | 402 ++++++++++++++++++
 .../CentralUnit/PlantSystem_WebAPI.ino        | 241 +++++++++++
 .../Firmware/CentralUnit/wifi_credentials.h   |   7 +
 6 files changed, 903 insertions(+)
 create mode 100644 Part2_Central_board/Firmware/CentralUnit/CentralUnit.ino
 create mode 100644 Part2_Central_board/Firmware/CentralUnit/CentralUnit_cfg.h
 create mode 100644 Part2_Central_board/Firmware/CentralUnit/PlantSystem.h
 create mode 100644 Part2_Central_board/Firmware/CentralUnit/PlantSystem_MainLogic.ino
 create mode 100644 Part2_Central_board/Firmware/CentralUnit/PlantSystem_WebAPI.ino
 create mode 100644 Part2_Central_board/Firmware/CentralUnit/wifi_credentials.h

diff --git a/Part2_Central_board/Firmware/CentralUnit/CentralUnit.ino b/Part2_Central_board/Firmware/CentralUnit/CentralUnit.ino
new file mode 100644
index 0000000..405efa7
--- /dev/null
+++ b/Part2_Central_board/Firmware/CentralUnit/CentralUnit.ino
@@ -0,0 +1,197 @@
+#include "WiFi.h"
+#include "ESPAsyncWebServer.h"
+#include "CentralUnit_cfg.h"
+#include "wifi_credentials.h"
+#include "PlantSystem.h"
+#include "Wire.h"
+
+AsyncWebServer server(80);
+int WiFi_status = WL_IDLE_STATUS; 
+uint32_t nFlowSensorCount = 0;
+
+void IRAM_ATTR ISR_flowSensor() {
+    nFlowSensorCount++;
+}
+
+
+void setup()
+{
+	pinMode(LED_PIN, OUTPUT);
+	digitalWrite(LED_PIN, HIGH);
+
+	pinMode(I2C_EN_PIN, OUTPUT);
+	digitalWrite(I2C_EN_PIN, HIGH);
+		
+	pinMode(WATER_PUMP_EN_PIN, OUTPUT);
+	digitalWrite(WATER_PUMP_EN_PIN, HIGH);
+		
+	pinMode(FLOW_SENSOR_PIN, INPUT_PULLUP);
+	
+	Serial.begin(115200);
+
+	Wire.begin(I2C_SDA_PIN, I2C_SCL_PIN);
+
+	// Connect to WiFi
+	while ( WiFi_status != WL_CONNECTED) {
+		Serial.print("Connecting to SSID: ");
+		Serial.println(ssid);
+		WiFi_status = WiFi.begin(ssid, password);
+
+		// wait 5 seconds for connection:
+		delay(5000);
+	}
+
+	Serial.print("WiFi IP: ");
+	Serial.println(WiFi.localIP());
+
+	digitalWrite(LED_PIN, LOW);
+
+	setupWebServer();
+	server.begin();
+
+	attachInterrupt(WATER_PUMP_EN_PIN, ISR_flowSensor, FALLING);
+}
+
+
+void loop()
+{
+	while(1)
+	{
+		PlantSystem_tick();
+	}
+}
+
+
+
+void setupWebServer(void)
+{
+	server.onNotFound([](AsyncWebServerRequest *request){
+	  request->send(404);
+	});
+
+	// send a file when /index is requested
+	server.on("/index.html", HTTP_ANY, [](AsyncWebServerRequest *request){
+		request->send(200, "text/plain", "Plant System v0.1");
+	});
+
+	// send a file when / is requested
+	server.on("/", HTTP_ANY, [](AsyncWebServerRequest *request){
+		request->send(200, "text/plain", "Plant System v0.1");
+	});
+
+
+	// Get sensors on the bus
+	server.on("/sensorData", HTTP_GET, [] (AsyncWebServerRequest *request) {
+		Serial.println("Sensor data");
+
+		char buff[300] = {0};
+		if(PlantSystem_WAPI_SensorData(buff, 300) == true)
+		{
+			request->send(200, "text/plain", buff);
+			return;
+		}
+		else
+		{
+			Serial.println("PlantSystem_WAPI_SensorData() error");
+			request->send(200, "text/plain", "PlantSystem_WAPI_SensorData() FAIL");
+			return;
+		}
+	});
+
+	// Get solenoids on the bus
+	server.on("/solenoidData", HTTP_GET, [] (AsyncWebServerRequest *request) {
+		Serial.println("Solenoid data");
+
+		char buff[300] = {0};
+		if(PlantSystem_WAPI_SolenoidList(buff, 300) == true)
+		{
+			request->send(200, "text/plain", buff);
+			return;
+		}
+		else
+		{
+			Serial.println("PlantSystem_WAPI_SolenoidList() error");
+			request->send(200, "text/plain", "PlantSystem_WAPI_SolenoidList() FAIL");
+			return;
+		}
+	});
+
+
+	// Get devices on the bus
+	server.on("/deviceData", HTTP_GET, [] (AsyncWebServerRequest *request) {
+		Serial.println("Device data");
+
+		char buff[300] = {0};
+		if(PlantSystem_WAPI_GetDevices(buff, 300) == true)
+		{
+			request->send(200, "text/plain", buff);
+			return;
+		}
+		else
+		{
+			Serial.println("PlantSystem_WAPI_GetDevices() error");
+			request->send(200, "text/plain", "PlantSystem_WAPI_GetDevices() FAIL");
+			return;
+		}
+	});
+
+	// Get devices on the bus
+	server.on("/flowSensor", HTTP_GET, [] (AsyncWebServerRequest *request) {
+		Serial.println("Flow sensor data");
+
+		char buff[100] = {0};
+		int len;
+		len = snprintf(buff, 100, "{flowSensor:%d}", nFlowSensorCount);
+
+		if(len>0)
+		{
+			request->send(200, "text/plain", buff);
+			return;
+		}
+		else
+		{
+			Serial.println("PlantSystem_WAPI_GetDevices() error");
+			request->send(200, "text/plain", "nFlowSensorCount FAIL");
+			return;
+		}
+	});
+
+
+	// Get devices on the bus
+	server.on("/setSolenoid", HTTP_GET, [] (AsyncWebServerRequest *request) {
+		Serial.println("Set solenoid to state");
+
+		if ( request->hasParam("address") && request->hasParam("state") )
+		{
+			String xAddress;
+			String xState;
+
+			uint32_t nAddress 	= 0;
+			uint32_t nState 	= 0;
+
+			xAddress = request->getParam("address")->value();
+			nAddress = xAddress.toInt();
+
+			xState = request->getParam("state")->value();
+			nState = xState.toInt();
+
+			if(PlantSystem_SetSolenoidState(nAddress, nState) == true)
+			{
+				request->send(200, "text/plain", "OK");
+				return;
+			}
+			else
+			{
+				Serial.println("PlantSystem_SetSolenoidState() error");
+				request->send(200, "text/plain", "PlantSystem_SetSolenoidState() FAIL");
+				return;
+			}
+		}
+		else
+		{
+			request->send(200, "text/plain", "MISSING ARGUMENTS");
+			return;
+		}
+	});
+}
+
diff --git a/Part2_Central_board/Firmware/CentralUnit/CentralUnit_cfg.h b/Part2_Central_board/Firmware/CentralUnit/CentralUnit_cfg.h
new file mode 100644
index 0000000..b8c22e1
--- /dev/null
+++ b/Part2_Central_board/Firmware/CentralUnit/CentralUnit_cfg.h
@@ -0,0 +1,13 @@
+#ifndef __CENTRAL_UNIT_CFG
+#define __CENTRAL_UNIT_CFG
+
+#define LED_PIN					2
+
+#define I2C_SDA_PIN				21
+#define I2C_SCL_PIN				22
+#define I2C_EN_PIN				19
+
+#define WATER_PUMP_EN_PIN		12
+#define FLOW_SENSOR_PIN			26
+
+#endif
\ No newline at end of file
diff --git a/Part2_Central_board/Firmware/CentralUnit/PlantSystem.h b/Part2_Central_board/Firmware/CentralUnit/PlantSystem.h
new file mode 100644
index 0000000..2eba104
--- /dev/null
+++ b/Part2_Central_board/Firmware/CentralUnit/PlantSystem.h
@@ -0,0 +1,43 @@
+#ifndef __PLANTSYSTEM_COMMS_H
+#define __PLANTSYSTEM_COMMS_H
+
+#include <stdbool.h>
+
+// CMD (1byte) + DATATYPE (1byte) + DATALEN (2bytes) 
+#define PLANTSYSTEM_MIN_HEADER_LENGHT	4
+
+typedef enum 
+{
+	CMD_FIRST = 0x00,
+	CMD_GET_DEVICE_INFO,
+	CMD_GET_TEMPERATURE,
+	CMD_GET_SOILMOISTURE,
+	CMD_GET_AMBIENTLIGHT,
+	CMD_GET_SOLENOID_STATE,
+	CMD_SET_SOLENOID_STATE,
+	CMD_LAST
+} plant_cmd_t;
+
+
+typedef enum 
+{
+	DATATYPE_FIRST = 0x00,
+	DATATYPE_NONE,
+	DATATYPE_SINGLE_VALUE,
+	DATATYPE_KEY_VALUE_PAIR,
+	DATATYPE_LAST
+} plant_dataType_t;
+
+
+
+typedef enum 
+{
+	DEVICETYPE_FIRST = 0x00,
+	DEVICETYPE_SENSOR_V1,
+	DEVICETYPE_SOLENOID_V1,
+	DEVICETYPE_LAST
+} plant_deviceType_t;
+
+bool PlanSystem_ParseBuffer(uint8_t *pBuffer, uint8_t nBufferLen, uint8_t *cmd, uint8_t *dataType, uint8_t *dataLength);
+
+#endif
\ No newline at end of file
diff --git a/Part2_Central_board/Firmware/CentralUnit/PlantSystem_MainLogic.ino b/Part2_Central_board/Firmware/CentralUnit/PlantSystem_MainLogic.ino
new file mode 100644
index 0000000..1d20141
--- /dev/null
+++ b/Part2_Central_board/Firmware/CentralUnit/PlantSystem_MainLogic.ino
@@ -0,0 +1,402 @@
+// Plant system note
+// CMD (1byte) + DATATYPE (1byte) + DATALEN (2bytes) 
+
+
+// Typedefs to allow us easier tracking on devices on the bus and storing received data
+typedef struct I2C_Device_TypeDef
+{
+    uint8_t i2cAddress;
+    uint8_t deviceType;
+} I2C_Device_TypeDef; 
+
+typedef struct I2C_Sensor_TypeDef
+{
+    uint8_t i2cAddress;
+    float temperature;
+    uint32_t soilMoisture;
+    uint32_t ambienLight;
+} I2C_Sensor_TypeDef;
+
+typedef struct I2C_Solenoid_TypeDef
+{
+    uint8_t i2cAddress;
+    uint8_t lastState;
+} I2C_Solenoid_TypeDef;
+
+// Every device that we saw on the bus
+I2C_Device_TypeDef gDevicesOnBus[250] = { {.i2cAddress=0, .deviceType=0} };
+uint8_t gDevicesOnBusCount = 0;
+
+// All sensors that are registered on the bus
+I2C_Sensor_TypeDef gSensorsOnBus[20] = { {.i2cAddress=0, .temperature=0.0, .soilMoisture=0, .ambienLight=0} };
+uint8_t gnSensorsOnBusCnt = 0;
+
+// All solenoids that are on the bus
+I2C_Solenoid_TypeDef gSolenoidsOnBus[20] = { {.i2cAddress=0, .lastState=0} };
+uint8_t gnSolenoidsOnBusCnt = 0;
+
+// Periods
+#define PERIOD_RESCAN_BUS		24*3600*1000	// Every 24h
+#define PERIOD_RELOAD_SENSORS	15*1000			// Every 5sec
+
+uint32_t nPeriod_Rescanbus=0;
+uint32_t nPeriod_ReloadSensors=0;
+
+void PlantSystem_tick(void)
+{
+	// -- Rescan I2C bus
+	if(nPeriod_Rescanbus <= millis())
+	{
+		PlantSystem_ScanBus();
+		#if 1
+		PlantSystem_debugShowDevicesOnBus();
+		#endif
+		nPeriod_Rescanbus = millis() + PERIOD_RESCAN_BUS;
+	}
+
+	// -- Reload sensor data
+	if(nPeriod_ReloadSensors <= millis())
+	{
+		PlantSystem_UpdateSensors();
+		nPeriod_ReloadSensors = millis() + PERIOD_RELOAD_SENSORS;
+	}
+	
+}
+
+
+void PlantSystem_ScanBus(void)
+{
+	Serial.println ("Scanning I2C bus...");
+	for (uint8_t i = 8; i< 127; i++)
+	{
+		Wire.beginTransmission (i);          // Begin I2C transmission Address (i)
+		if (Wire.endTransmission () == 0)  	// Receive 0 = success (ACK response) 
+		{
+			gDevicesOnBus[gDevicesOnBusCount++].i2cAddress = i;
+			// gDevicesOnBusCount++;
+		}
+	}
+	Serial.print ("Found ");      
+	Serial.print (gDevicesOnBusCount, DEC);        // numbers of devices
+	Serial.println (" device(s).");
+
+	for(uint8_t i=0; i<gDevicesOnBusCount; i++)
+	{
+		PlantSystem_getDeviceInfo(i);
+	}
+}
+
+
+void PlantSystem_debugShowDevicesOnBus(void)
+{
+	uint8_t count = 0;
+
+	// -- Print all devices
+	Serial.print ("There are total of ");
+	Serial.print (gDevicesOnBusCount, DEC);        // numbers of devices
+	Serial.println (" device(s) on I2C bus.");
+
+	for (uint8_t i = 0; i< gDevicesOnBusCount; i++)
+	{
+		Serial.print ("Device @ 0x");
+		Serial.print (gDevicesOnBus[i].i2cAddress, HEX);        // numbers of devices
+		if(gDevicesOnBus[i].deviceType == DEVICETYPE_SENSOR_V1)
+		{
+			Serial.println (" registered as Temp+ALS+SoilMoisture.");
+		}
+		else if(gDevicesOnBus[i].deviceType == DEVICETYPE_SOLENOID_V1)
+		{
+			Serial.println (" registered as Solenoid driver");
+		}
+		else if(gDevicesOnBus[i].deviceType == 0x00 || gDevicesOnBus[i].deviceType == 0xFF)
+		{
+			Serial.println (" responded with invalid value?!");
+		}
+		else if(gDevicesOnBus[i].deviceType <= DEVICETYPE_FIRST || gDevicesOnBus[i].deviceType >= DEVICETYPE_LAST)
+		{
+			Serial.println (" responded with unsupported value.");
+		}
+		
+	}
+
+	// -- Print all sensors
+	Serial.print ("There are total of ");
+	Serial.print (gnSensorsOnBusCnt, DEC);        // numbers of devices
+	Serial.println (" SENSORS on I2C bus.");
+	for (uint8_t i = 0; i< gnSensorsOnBusCnt; i++)
+	{
+		Serial.print("Sensor @ 0x");
+		Serial.println (gSensorsOnBus[i].i2cAddress, HEX);        // numbers of devices
+	}
+
+	// -- Print all solenoids
+	Serial.print ("There are total of ");
+	Serial.print (gnSolenoidsOnBusCnt, DEC);        // numbers of devices
+	Serial.println (" SOLENOIDS on I2C bus.");
+	for (uint8_t i = 0; i< gnSolenoidsOnBusCnt; i++)
+	{
+		Serial.print("Solenoid @ 0x");
+		Serial.println (gSolenoidsOnBus[i].i2cAddress, HEX);        // numbers of devices
+	}
+
+}
+
+// -- Get device info
+// Used to get information from the device (type of device i.e. sensor or solenoid etc).
+// Add each device to gDevicesOnBus
+// Also add to gSensorsOnBus if type is sensor or gSolenoidsOnBus if type is solenoid
+void PlantSystem_getDeviceInfo(uint8_t devID)
+{
+	if(devID > gDevicesOnBusCount)
+	{
+		Serial.println("Invalid device ID");
+		return;
+	}
+
+	if(gDevicesOnBus[devID].i2cAddress == 0)
+	{
+		Serial.println("Invalid device I2C address");
+		return;
+	}
+
+	Serial.print("I2C: Talking to address 0x");
+	Serial.println(gDevicesOnBus[devID].i2cAddress, HEX);
+	
+	uint8_t txBuffer[4] = {CMD_GET_DEVICE_INFO, DATATYPE_NONE, 0, 0};
+
+	I2C_SendBuffer(gDevicesOnBus[devID].i2cAddress, txBuffer, 4);
+	delay(200);
+
+	uint8_t deviceType = 0;
+	I2C_ReadFrom(gDevicesOnBus[devID].i2cAddress, 10,  &deviceType, PLANTSYSTEM_MIN_HEADER_LENGHT+1, 1);
+	gDevicesOnBus[devID].deviceType = deviceType;
+
+	// Finally add sensors to gSensorsOnBus and solenoids to gSolenoidsOnBus
+	if(deviceType == DEVICETYPE_SENSOR_V1)
+	{
+		gSensorsOnBus[gnSensorsOnBusCnt++].i2cAddress = gDevicesOnBus[devID].i2cAddress;
+	}
+	else if(deviceType == DEVICETYPE_SOLENOID_V1)
+	{
+		gSolenoidsOnBus[gnSolenoidsOnBusCnt++].i2cAddress = gDevicesOnBus[devID].i2cAddress;
+	}
+
+	#if 0
+	Serial.println ("Response");
+	for(uint8_t i=0; i<10; i++)
+	{
+		Serial.print ("[");
+		Serial.print (i, DEC);
+		Serial.print ("] = 0x");
+		Serial.println (rxBuffer[i], HEX);
+	}
+	#endif
+
+}
+
+// -- 
+bool PlantSystem_SetSolenoidState(uint32_t I2CAddress, bool energized)
+{
+	if(I2CAddress < 0x08 || I2CAddress > 0x7F )
+	{
+		return false;
+	}
+	
+	uint8_t txBuffer[5];
+	uint8_t requestedState = (energized ? 1 : 0);
+
+	// Send new solenoid value
+	txBuffer[0] = CMD_SET_SOLENOID_STATE;
+	txBuffer[1] = DATATYPE_SINGLE_VALUE;
+	txBuffer[2] = 0;
+	txBuffer[3] = 1;
+	txBuffer[4] = requestedState;
+	I2C_SendBuffer(I2CAddress, txBuffer, 5);
+
+	// Wait 100 ms
+	delay(100);
+
+	// Send read back value request
+	txBuffer[0] = CMD_GET_SOLENOID_STATE;
+	txBuffer[1] = DATATYPE_NONE;
+	txBuffer[2] = 0;
+	txBuffer[3] = 0;
+	I2C_SendBuffer(I2CAddress, txBuffer, 4);
+	
+	// Wait 100 ms
+	delay(100);
+
+	// Read new solenoid state
+	uint8_t newState = 0;
+	I2C_ReadFrom(I2CAddress, 10, &newState, PLANTSYSTEM_MIN_HEADER_LENGHT+1, 1);
+
+	if(requestedState == newState)
+	{
+		return true;
+	}
+	else
+	{
+		return false;
+	}
+
+}
+
+
+// -- Read data from each registered sensor
+// Temperature, Soil moisture and ambient light
+void PlantSystem_UpdateSensors(void)
+{
+	uint8_t txBuffer[4] = {CMD_GET_TEMPERATURE, DATATYPE_NONE, 0, 0};
+	uint8_t rxBuffer[4] = {0};
+
+	Serial.print("Reading data from sensors...");
+	for(uint8_t i=0; i<gnSensorsOnBusCnt; i++)
+	{
+		#if 0
+		Serial.print("Reading from sensor #");
+		Serial.print(i, DEC);
+		Serial.print(" address: 0x");
+		Serial.println(gSensorsOnBus[i].i2cAddress, HEX);
+		#endif
+
+		// -- Temperature
+		// Send read temperature request
+		txBuffer[0] = CMD_GET_TEMPERATURE;
+		I2C_SendBuffer(gSensorsOnBus[i].i2cAddress, txBuffer, 4);
+		delay(200);
+
+		// Read response
+		I2C_ReadFrom(gSensorsOnBus[i].i2cAddress, 10, rxBuffer, PLANTSYSTEM_MIN_HEADER_LENGHT+1, 2);
+		gSensorsOnBus[i].temperature = rxBuffer[0] + rxBuffer[1]/10;
+		delay(200);
+
+		#if 0
+		Serial.print("T: ");
+		Serial.print(rxBuffer[0], DEC);
+		Serial.println(rxBuffer[1], DEC);
+		#endif
+
+		// -- Soil moisture
+		// Send read soilmositure request
+		txBuffer[0] = CMD_GET_SOILMOISTURE;
+		I2C_SendBuffer(gSensorsOnBus[i].i2cAddress, txBuffer, 4);
+		delay(200);
+
+		// Read response
+		I2C_ReadFrom(gSensorsOnBus[i].i2cAddress, 10, rxBuffer, PLANTSYSTEM_MIN_HEADER_LENGHT+1, 4);
+		gSensorsOnBus[i].soilMoisture = (rxBuffer[0]<<24) | (rxBuffer[1]<<16) | (rxBuffer[2]<<8) | (rxBuffer[3]);
+		delay(200);
+
+		#if 0
+		Serial.print("M: ");
+		Serial.print(rxBuffer[0], DEC);
+		Serial.print(rxBuffer[1], DEC);
+		Serial.print(rxBuffer[2], DEC);
+		Serial.println(rxBuffer[3], DEC);
+		#endif
+
+		// -- Ambient light
+		// Send read soilmositure request
+		txBuffer[0] = CMD_GET_AMBIENTLIGHT;
+		I2C_SendBuffer(gSensorsOnBus[i].i2cAddress, txBuffer, 4);
+		delay(200);
+
+		// Read response
+		I2C_ReadFrom(gSensorsOnBus[i].i2cAddress, 10, rxBuffer, PLANTSYSTEM_MIN_HEADER_LENGHT+1, 4);
+		gSensorsOnBus[i].ambienLight = (rxBuffer[0]<<24) | (rxBuffer[1]<<16) | (rxBuffer[2]<<8) | (rxBuffer[3]);
+		delay(200);
+
+		#if 0
+		Serial.print("A: ");
+		Serial.print(rxBuffer[0], DEC);
+		Serial.print(rxBuffer[1], DEC);
+		Serial.print(rxBuffer[2], DEC);
+		Serial.println(rxBuffer[3], DEC);
+		#endif
+
+		#if 0
+		Serial.print("Sensor #");
+		Serial.println(i, DEC);
+
+		Serial.print("T: ");
+		Serial.println((float)gSensorsOnBus[i].temperature, 1);
+
+		Serial.print("S: ");
+		Serial.println(gSensorsOnBus[i].soilMoisture, DEC);
+
+		Serial.print("A: ");
+		Serial.println(gSensorsOnBus[i].ambienLight, DEC);
+		#endif
+	}
+	Serial.println("done.");
+
+}
+
+// -- Send `nLen` bytes from `pBuffer` to `address` I2C address
+void I2C_SendBuffer(uint8_t address, uint8_t *pBuffer, uint8_t nLen)
+{
+	Wire.beginTransmission(address); // transmit to device
+	for(uint8_t i=0; i<nLen; i++)
+	{
+		Wire.write(pBuffer[i]);
+	}
+	Wire.endTransmission();    // stop transmitting}
+}
+
+
+// -- Read `nLen` bytes from `address` I2C address
+// Then store (return) `nBytes` to `pData` starting from `nPos` (discard)
+bool I2C_ReadFrom(uint8_t address, uint8_t nLen, uint8_t *pData, uint8_t nPos, uint8_t nBytes)
+{
+	if(nLen > 20)
+	{
+		Serial.println("Invalid length!");
+		return false;
+	}
+
+	if(pData == NULL && nBytes > 0)
+	{
+		Serial.println("Invalid pointer!");
+		return false;
+	}
+
+	if(nBytes+nPos > nLen)
+	{
+		Serial.println("Buffer overflow");
+		return false;
+	}
+
+	uint8_t rxBuffer[20] = {0};
+
+	Wire.requestFrom(address, nLen, true);
+	while(Wire.available() == 0);
+	for(uint8_t i=0; i<nLen; i++)
+	{
+		rxBuffer[i] = Wire.read();
+	}
+	Wire.endTransmission();    // stop transmitting
+
+	// Copy over bytes
+	if(nBytes > 0)
+	{
+		for(uint8_t i=0; i<nBytes; i++)
+		{
+			pData[i] = rxBuffer[nPos+i];
+		}
+	}
+
+	#if 0
+	Serial.println ("Response");
+	for(uint8_t i=0; i<nLen; i++)
+	{
+		Serial.print ("[");
+		Serial.print (i, DEC);
+		Serial.print ("] = 0x");
+		Serial.println (rxBuffer[i], HEX);
+	}
+	#endif
+
+	return true;
+}
+
+
diff --git a/Part2_Central_board/Firmware/CentralUnit/PlantSystem_WebAPI.ino b/Part2_Central_board/Firmware/CentralUnit/PlantSystem_WebAPI.ino
new file mode 100644
index 0000000..dfab75f
--- /dev/null
+++ b/Part2_Central_board/Firmware/CentralUnit/PlantSystem_WebAPI.ino
@@ -0,0 +1,241 @@
+extern I2C_Device_TypeDef gDevicesOnBus[250];
+extern uint8_t gDevicesOnBusCount;
+
+extern I2C_Sensor_TypeDef gSensorsOnBus[20];
+extern uint8_t gnSensorsOnBusCnt;
+
+extern I2C_Solenoid_TypeDef gSolenoidsOnBus[20];
+extern uint8_t gnSolenoidsOnBusCnt;
+
+// -- Format char buffer to return data as JSON object
+// JSON object will have item count and then each item's
+// I2C address and as what type device registered.
+bool PlantSystem_WAPI_GetDevices(char *pBuff, uint32_t nMaxLen)
+{
+	if(pBuff == NULL)
+	{
+		return false;
+	}
+	if(nMaxLen <= 2)
+	{
+		return false;
+	}
+
+	uint32_t currentPos = 0;
+	int len;
+
+	char str_sensor[] = "sensor";
+	char str_solenoid[] = "solenoid";
+	char str_unknown[] = "unknown";
+ 	char *pStrDevTyep = str_unknown;
+
+	// Start JSON string
+	len = snprintf(&pBuff[currentPos], (nMaxLen-currentPos), "{\"count\":%d,\"devices\":[", 
+																gDevicesOnBusCount);
+	if(len<0)
+	{
+		Serial.println("Buffer too short");
+		return false;
+	}
+	else
+	{
+		currentPos += len;
+	}
+
+	// Construct response based on devices currently registered on the bus
+	for(uint8_t i=0; i<gDevicesOnBusCount; i++)
+	{
+		if(gDevicesOnBus[i].deviceType == DEVICETYPE_SENSOR_V1)
+		{
+			pStrDevTyep = str_sensor;
+		}
+		else if (gDevicesOnBus[i].deviceType == DEVICETYPE_SOLENOID_V1)
+		{
+			pStrDevTyep = str_solenoid;
+		}
+		else
+		{
+			pStrDevTyep = str_unknown;
+		}
+
+
+		len = snprintf(&pBuff[currentPos], (nMaxLen-currentPos), "{\"address\":\"0x%02X\",\"type\":\"%s\"},",
+							gDevicesOnBus[i].i2cAddress, 
+							pStrDevTyep);
+		if(len>0)
+		{
+			currentPos += len;
+		}
+		else
+		{
+			Serial.println("Len issue");
+			Serial.println(len, DEC);
+			return false;
+		}
+	}
+
+	// Close JSON string
+	len = snprintf(&pBuff[currentPos-1], (nMaxLen-currentPos), "]}");
+
+	if(len >0 && currentPos <nMaxLen)
+	{
+		#if 0
+		Serial.println("Printing pBuff");
+		Serial.println(pBuff);
+		#endif
+		return true;
+	}
+	else
+	{
+		return false;
+	}
+}
+
+
+// -- Format char buffer to return data as JSON object
+// JSON object will have total sensors count and then sensors
+// will contain each sensors I2C address and what is last reported
+// temperature, soil moisture and ambient light
+bool PlantSystem_WAPI_SensorData(char *pBuff, uint32_t nMaxLen)
+{
+	if(pBuff == NULL)
+	{
+		return false;
+	}
+	if(nMaxLen <= 64)
+	{
+		return false;
+	}
+
+	uint32_t currentPos = 0;
+	int len;
+
+
+	// Start JSON string
+	len = snprintf(&pBuff[currentPos], (nMaxLen-currentPos), "{\"count\":%d,\"sensors\":[",
+																gnSensorsOnBusCnt);
+	if(len<0)
+	{
+		Serial.println("Buffer too short");
+		return false;
+	}
+	else
+	{
+		currentPos += len;
+	}
+
+	// Construct response based on devices currently registered on the bus
+	for(uint8_t i=0; i<gnSensorsOnBusCnt; i++)
+	{
+		len = snprintf(&pBuff[currentPos], (nMaxLen-currentPos), "{\"address\":\"0x%02X\",\"T\":%.2f,\"M\":%d,\"A\":%d},",
+									gSensorsOnBus[i].i2cAddress, 
+									gSensorsOnBus[i].temperature, 
+									gSensorsOnBus[i].soilMoisture,
+									gSensorsOnBus[i].ambienLight);
+		if(len>0)
+		{
+			currentPos += len;
+		}
+		else
+		{
+			Serial.println("Len issue");
+			Serial.println(len, DEC);
+			return false;
+		}
+	}
+
+
+	// Close JSON string
+	len = snprintf(&pBuff[currentPos-1], (nMaxLen-currentPos), "]}");
+	if(len<0)
+	{
+		Serial.println("Buffer too short");
+		return false;
+	}
+
+	if(len>0 && currentPos <nMaxLen)
+	{
+		#if 0
+		Serial.println("Printing pBuff");
+		Serial.println(pBuff);
+		#endif
+		return true;
+	}
+	else
+	{
+		return false;
+	}
+}
+
+
+// -- Format char buffer to return data as JSON object
+// JSON object will have total solenoids count and then I2C
+// address of each sensor
+bool PlantSystem_WAPI_SolenoidList(char *pBuff, uint32_t nMaxLen)
+{
+	if(pBuff == NULL)
+	{
+		return false;
+	}
+	if(nMaxLen <= 32)
+	{
+		return false;
+	}
+
+	uint32_t currentPos = 0;
+	int len;
+
+
+	// Start JSON string
+	len = snprintf(&pBuff[currentPos], (nMaxLen-currentPos), "{\"count\":%d,\"solenoids\":[",
+																gnSolenoidsOnBusCnt);
+	if(len<0)
+	{
+		Serial.println("Buffer too short");
+		return false;
+	}
+	else
+	{
+		currentPos += len;
+	}
+
+	// Construct response based on devices currently registered on the bus
+	for(uint8_t i=0; i<gnSolenoidsOnBusCnt; i++)
+	{
+		len = snprintf(&pBuff[currentPos], (nMaxLen-currentPos), "\"0x%02X\",",
+									gSolenoidsOnBus[i].i2cAddress);
+
+		if(len>0)
+		{
+			currentPos += len;
+		}
+		else
+		{
+			Serial.println("Len issue");
+			Serial.println(len, DEC);
+			return false;
+		}
+	}
+
+
+	// Close JSON string
+	len = snprintf(&pBuff[currentPos-1], (nMaxLen-currentPos), "]}");
+	if(len<0)
+	{
+		Serial.println("Buffer too short");
+		return false;
+	}
+
+	if(len>0 && currentPos <nMaxLen)
+	{
+		#if 0
+		Serial.println("Printing pBuff");
+		Serial.println(pBuff);
+		#endif
+		return true;
+	}
+	else
+	{
+		return false;
+	}
+}
diff --git a/Part2_Central_board/Firmware/CentralUnit/wifi_credentials.h b/Part2_Central_board/Firmware/CentralUnit/wifi_credentials.h
new file mode 100644
index 0000000..e377195
--- /dev/null
+++ b/Part2_Central_board/Firmware/CentralUnit/wifi_credentials.h
@@ -0,0 +1,7 @@
+#ifndef __WIFI_CRED_CFG
+#define __WIFI_CRED_CFG
+
+const char* ssid = "Koshon";
+const char* password =  "sxdcfvgbhnjmk";
+
+#endif
\ No newline at end of file