Alexa ESP32 libraries

Overview

In this IoT project, I demonstrate how to set up Manual & Smart Home Automation project with Alexa using the ESP32 and Amazon Echo Echo Dot. This ESP32 Alexa Home Automation project solely relies on the Amazon Alexa App for controlling home devices with 4 relays. Even without the internet, you can manage devices with push buttons. Once the device is online, the ESP32 auto-connects to WiFi, preserving the relay module’s last state.

Earlier we built ESP32 Home Automation project using Blynk, AWS IoT Core and Arduino IoT Cloud. We have designed the custom PCB for this project to make the device portable. We have also provided the complete schematic, PCB details, Gerber File, Bill of Materials and Source Code. The system works without any third-party IoT apps, making it straightforward for home automation setup.

Bill of Materials

For this project, we will need the following components. The component list, footprint, and quantity are given below.

S.N.	Component	Designator	Footprint	Quantity
1	Capacitor 100nf	C1, C3, C6, C7, C8, C9, C10, C11	CAP_0805	8
2	Capacitor 10uf	C2, C4, C5	CAP_0805	3
3	Capacitor 220uF, 25V	C12	FP-RAD-TH-D_10_0_5-L_16_1-MFG	1
4	Diode 1N4007	D1, D2, D3, D4	DIOM5027X262N	4
5	SP4322-01ETG	D5	SP432201ETG	1
6	Optocoupler PC817C	IC1, IC3, IC4, IC5	DIP762W60P254L458H450Q4N	4
7	ESP32 WROOM-32	IC2	ESP32WROOM3216MB	1
8	2-Pin Terminal Block	J1		1
9	3-Pin Terminal Block	J2, J3, J4, J5		4
10	Relay SRD-05VDC-SL-C	K1, K2, K3, K4	SRD	4
11	LED Red	LED1, LED2, LED3, LED4, LED5	LEDC2012X80N	5
12	Male Header 6 Pin	P1	HDR1X6	1
13	HLK-10M05	PS1	HLK10M05	1
14	Transistor BC847B	Q1, Q2, Q3, Q4, Q5, Q6	BC847B215	6
15	Resistor 220R	R1, R3, R9, R11, R14, R16, R17, R19	805	8
16	DNP	R2, R10, R15, R18	805	4
17	Resistor 12K	R4, R12, R13	805	3
18	Resistor 1K	R5, R7, R8, R24	805	4
19	Resistor 470R	R6	805	1
20	Resistor 10K	R20, R21, R22, R23	805	4
21	Push Button Switch	S1, S2, S3, S4	B3W1020	4
22	Manual Switch (Optional)	SW1, SW2, SW3, SW4	HDR1X2	4
23	HT7333 3.3V Voltage Regulator	U1	IC_HT7333	1

Circuit Diagram & Hardware Design

Let us take a look at the Schematic of Alexa Based Manual & Smart Home Automation Project with ESP32 . The schematic is drawn using the Altium Designer Software.

We used SMD resistors, capacitors, and LED with the 0805 package. To convert 220V AC to 5V DC, we used an AC-to-DC Converter from Hi-Link. For providing power to ESP32 raw chip and other peripherals, a low-power LDO HT7333 IC was used. To separate the high-power line from the 3.3V circuit PC817 optocoupler IC is used. The LED5 in the circuit is used to indicate power.

Similarly the LED1, LED2, LED3 & LED4 is used to represent Relay1, Relay2, Relay3 & Relay4 output respectively. The LED5 is a power indication LED. The 4 Relays are connected to ESP32 via GPIO Pins 12, 14, 27, 26. The push buttons SW1, SW2, SW3, and SW4 are used in the manual controlling of Relays. They are connected to GPIO Pins 5, 17, 13, 16. You may attach a manual switch there and program the controller to control the circuit.

You can connect 4 home appliannces using the Relay connections at 3 Pin Terminal J2, J3. J4, J5. The 2 Pin Terminal J1 is used to supply AC Power directly to the Circuit. A Capacitor C12 of 220uF, 25V is connected to PCB stop voltage fluctuations.

To program the ESP32 raw chip, the FTDI pin is provided. We can connect an FTDI Module (USB-to-TTL Converter) to program the ESP32 Chip directly.

Project PCB Gerber File & PCB Ordering Online

We have designed the PCB using the Altium Designer Software. It took quite a lot of time fixing all the isses in the PCB but still we managed to design a complete working custom PCB. The PCB design looks like this.

Here is the 3D View of the PCB from the front side as well as from the backside.

The Gerber File for the PCB is given below. You can simply download the Gerber File and order the PCB from PCBGOGO at 1$ only.

Download Gerber File: ESP32 Home Automation Gerber File

You can use this Gerber file to order high-quality PCB for this project. To do that visit the PCBGOGO official website by clicking here: https://www.pcbgogo.com/.

You can now upload the Gerber File by choosing the Quote Now option. From these options, you can choose the Material Type, Dimensions, Quantity, Thickness, Solder Mask Color and other required parameters.

After filling all details, select your country and shipping method. Finally you can place the order.

PCB & Hardware Assembly

After ordering the PCB, it took almost 5 days and I got my PCB.

The PCB quality from PCBGOGO is superb with very high quality. That is why most people trust PCBGOGO for PCB/PCBA Services.

First solder all the SMD components like resistors, capacitors, transistors, LEDs, voltage regulators & diodes. Be careful about the SMD LED polarity, place it in the proper direction. The SMD soldering is to be done on the both sides.

After soldering all these, you can solder the ESP32 raw chip. The final stage would be soldering all the through-hole components like Optocoupler IC, terminal block, Relays, male-female headers, and AC-to-DC Converter Module.

After soldering all the components, the ESP32 Alexa Manual & Smart Home Automation Board is ready for the test. You can upload a blink sketch by connecting a USB-to-TTL Converter Module.

Note: There were some voltage fluctuation issues in the designed PCB, so I have updated the design by adding 220uF capacitor. Also, some connection issues have been fixed. The Gerber file above is updated and the PCB would be little different from shown above. But overall the functionality is same.

Espalexa Library

In this project, we will be using the Espalexa library to integrate the ESP32 Home Automation Board with Alexa Echo Dot.

Download: Espalexa Library

So, you’ve got this cool library called Espalexa. What’s it all about? Imagine being able to chat with Alexa and get her to control your ESP gadgets such as ESP32 . This library makes that chat a breeze, and the best part? It’s all packed into an Arduino-friendly format.

Now, what sets Espalexa apart from other similar tools? Well, it gives you a ton of flexibility with voice commands. Instead of just turning things on or off, you can get precise. Tell Alexa, “Hey, dim that light to 75%,” or “Can we get the room to 21 degrees?” And she’ll handle it.

Even cooler? Espalexa has jumped onto the color train! Now you can say, “Alexa, let’s get a blue mood in here,” and your light will change color. If you’re more into shades of white, it’s got you covered too. By the starting line, Espalexa can juggle up to 10 devices.

Source Code/Program for ESP32 Alexa Home Automation Project

Here is the code for the Smart & Manual Home Automation Project with Alexa & ESP32 . This code is all about giving you two ways to control devices in your home. Imagine you have four lamps, and each lamp is connected to a relay (which is like a remote-controlled switch). Now, with this code:

You can ask Alexa to turn on or adjust any of these lamps. “Alexa, turn on Lamp 1!” and it’ll do just that.
But what if your internet goes down? No worries! There are manual switches you can press to control the lamps too.
The system is smart enough to keep checking if it’s connected to the internet. If it finds a connection, it’ll set itself up so you can use Alexa. If not, it’ll keep working with the manual switches.

Here is the complete code. In this code make changes to the WiFi SSID and Password.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
// Include necessary libraries
#include <WiFi.h>
#include <Espalexa.h>
 
// =================== CONSTANTS ===================
// Define GPIO pins for relays and switches
#define RelayPin1 12
#define RelayPin2 14
#define RelayPin3 27
#define RelayPin4 26
 
#define SwitchPin1 5
#define SwitchPin2 17
#define SwitchPin3 13
#define SwitchPin4 16
 
const char* ssid = "******************";
const char* password = "******************";
 
String Device_1_Name = "Relay 1";
String Device_2_Name = "Relay 2";
String Device_3_Name = "Relay 3";
String Device_4_Name = "Relay 4";
 
// =================== VARIABLES ===================
int toggleState_1 = 0;
int toggleState_2 = 0;
int toggleState_3 = 0;
int toggleState_4 = 0;
boolean wifiConnected = false;
 
// Create an instance of the Espalexa class
Espalexa espalexa;
// =================== FUNCTION DECLARATIONS ===================
boolean connectWifi();
void firstLightChanged(uint8_t brightness);
void secondLightChanged(uint8_t brightness);
void thirdLightChanged(uint8_t brightness);
void fourthLightChanged(uint8_t brightness);
void relayOnOff(int relay);
void addDevices();
 
// =================== SETUP ===================
void setup()
{
  Serial.begin(115200); // Start serial communication
 
  // Initialize pins for relay and switches
  pinMode(RelayPin1, OUTPUT);
  pinMode(RelayPin2, OUTPUT);
  pinMode(RelayPin3, OUTPUT);
  pinMode(RelayPin4, OUTPUT);
  
  pinMode(SwitchPin1, INPUT_PULLUP);
  pinMode(SwitchPin2, INPUT_PULLUP);
  pinMode(SwitchPin3, INPUT_PULLUP);
  pinMode(SwitchPin4, INPUT_PULLUP);
 
  // Ensure all relays are turned off initially
  digitalWrite(RelayPin1, LOW);
  digitalWrite(RelayPin2, LOW);
  digitalWrite(RelayPin3, LOW);
  digitalWrite(RelayPin4, LOW);
 
  // Try connecting to WiFi
  wifiConnected = connectWifi();
  if (wifiConnected)
  {
    addDevices();
  }
  else
  {
    Serial.println("Cannot connect to WiFi. So in Manual Mode");
    delay(1000);
  }
}
 
// =================== MAIN LOOP ===================
void loop()
{
  // Handle manual switches regardless of WiFi status
  if (digitalRead(SwitchPin1) == LOW)
  {
    delay(200);
    relayOnOff(1);
  }
  else if (digitalRead(SwitchPin2) == LOW)
  {
    delay(200);
    relayOnOff(2);
  }
  else if (digitalRead(SwitchPin3) == LOW)
  {
    delay(200);
    relayOnOff(3);
  }
  else if (digitalRead(SwitchPin4) == LOW)
  {
    delay(200);
    relayOnOff(4);
  }
 
  // Handle WiFi connections
  if (wifiConnected)
  {
    espalexa.loop();
    delay(1);
  }
  else
  {
    wifiConnected = connectWifi(); // Try to reconnect if not connected
    if (wifiConnected)
    {
      addDevices();
    }
  }
}
 
// =================== FUNCTION IMPLEMENTATIONS ===================
boolean connectWifi()
{
  int attempts = 0;
  boolean state = true;
 
  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);
 
  Serial.println("Connecting to WiFi");
  while (WiFi.status() != WL_CONNECTED && attempts < 20)
  {
    delay(500);
    Serial.print(".");
    attempts++;
  }
 
  // Handle successful connection
  if (WiFi.status() == WL_CONNECTED)
  {
    Serial.print("Connected to ");
    Serial.println(ssid);
    Serial.print("IP address: ");
    Serial.println(WiFi.localIP());
  }
  else
  {
    state = false;
    Serial.println("Connection failed.");
  }
 
  return state;
}
 
 
// Functions for each relay to handle toggle operations
void relayOnOff(int relay)
{
  // Based on the relay number, toggle its state
  switch (relay)
  {
    case 1:
      if (toggleState_1 == 0)
      {
        digitalWrite(RelayPin1, HIGH); // turn on relay 1
        toggleState_1 = 1;
        Serial.println("Device1 ON");
      }
      else
      {
        digitalWrite(RelayPin1, LOW); // turn off relay 1
        toggleState_1 = 0;
        Serial.println("Device1 OFF");
      }
      delay(100);
      break;
 
    case 2:
      if (toggleState_2 == 0)
      {
        digitalWrite(RelayPin2, HIGH); // turn on relay 2
        toggleState_2 = 1;
        Serial.println("Device2 ON");
      }
      else
      {
        digitalWrite(RelayPin2, LOW); // turn off relay 2
        toggleState_2 = 0;
        Serial.println("Device2 OFF");
      }
      delay(100);
      break;
 
    case 3:
      if (toggleState_3 == 0)
      {
        digitalWrite(RelayPin3, HIGH); // turn on relay 3
        toggleState_3 = 1;
        Serial.println("Device3 ON");
      } else {
        digitalWrite(RelayPin3, LOW); // turn off relay 3
        toggleState_3 = 0;
        Serial.println("Device3 OFF");
      }
      delay(100);
      break;
 
    case 4:
      if (toggleState_4 == 0)
      {
        digitalWrite(RelayPin4, HIGH); // turn on relay 4
        toggleState_4 = 1;
        Serial.println("Device4 ON");
      }
      else
      {
        digitalWrite(RelayPin4, LOW); // turn off relay 4
        toggleState_4 = 0;
        Serial.println("Device4 OFF");
      }
      delay(100);
      break;
    default : break;
  }
}
 
 
// Functions to handle Alexa brightness changes for each device
void firstLightChanged(uint8_t brightness)
{
  // If brightness is set to 255, turn on the relay, otherwise turn it off
  if (brightness == 255)
  {
    digitalWrite(RelayPin1, HIGH);
    Serial.println("Device1 ON");
    toggleState_1 = 1;
  }
  else
  {
    digitalWrite(RelayPin1, LOW);
    Serial.println("Device1 OFF");
    toggleState_1 = 0;
  }
}
 
void secondLightChanged(uint8_t brightness)
{
  // If brightness is set to 255, turn on the relay, otherwise turn it off
  if (brightness == 255)
  {
    digitalWrite(RelayPin2, HIGH);
    Serial.println("Device2 ON");
    toggleState_2 = 1;
  }
  else
  {
    digitalWrite(RelayPin2, LOW);
    Serial.println("Device2 OFF");
    toggleState_2 = 0;
  }
}
 
void thirdLightChanged(uint8_t brightness)
{
  // If brightness is set to 255, turn on the relay, otherwise turn it off
  if (brightness == 255)
  {
    digitalWrite(RelayPin3, HIGH);
    Serial.println("Device3 ON");
    toggleState_3 = 1;
  }
  else
  {
    digitalWrite(RelayPin3, LOW);
    Serial.println("Device3 OFF");
    toggleState_3 = 0;
  }
}
 
void fourthLightChanged(uint8_t brightness)
{
  // If brightness is set to 255, turn on the relay, otherwise turn it off
  if (brightness == 255)
  {
    digitalWrite(RelayPin4, HIGH);
    Serial.println("Device4 ON");
    toggleState_4 = 1;
  }
  else
  {
    digitalWrite(RelayPin4, LOW);
    Serial.println("Device4 OFF");
    toggleState_4 = 0;
  }
}
 
 
// Function to add the devices for Alexa control
void addDevices()
{
  // Define the devices and their respective callback functions
  // and start the Espalexa service
  espalexa.addDevice(Device_1_Name, firstLightChanged); //simplest definition, default state off
  espalexa.addDevice(Device_2_Name, secondLightChanged);
  espalexa.addDevice(Device_3_Name, thirdLightChanged);
  espalexa.addDevice(Device_4_Name, fourthLightChanged);
 
  espalexa.begin();
}

To progam the ESP32  Raw Chip, connect the FTDI Module to your FTDI Pin of the PCB.
Then go to the tools & select ESP32  Dev Module that you are using for this project. Also, select the COM port. Then click on the upload option to upload the code to the ESP32 Chip.
Note: While uploading the code disconnect the relay from the power source.
Once the code uploading is done, open the Serial Monitor. The ESP32 will try connecting to the WiFi Network. Once it gets connected to the WiFi Network, the Serial Monitor will display the IP Address of ESP32 .
Now remove the FTDI Module connection and power the device using the AC Supply.
Setting up Alexa App & Echo  DotNow you need to setup the Alexa App and Alexa Echo  Dot for the Smart & Manual Home Automation using the ESP32 . Here are the steps for this.
Open the Alexa app on your smartphone.
Go to the Devices tab (found at the bottom right).
Tap on the ‘+‘ (plus) sign at the top-right.
Choose “Add Device“. Then Select “Light“.
Scroll down and choose “Other“. Then Select “WiFi“.
Tap on “Discover Devices“. Alexa will search for new devices.
The Alexa app will start searching for smart devices. After searching 4 devices will appear and the devices should be named “Relay 1“, “Relay 2“, “Relay 3“, and “Relay 4” as provided in the code.
Once Alexa finds the devices, they will be listed in the Alexa app.
You might encounter the “No new devices found” error when trying to add devices with Alexa. If this happens, restart your Echo  Dot. Once it reconnects to the same WiFi network, select “Try discovery again“.
From this Dashboard, you can turn on/off the 4 Relays in case, you wanna control through the app instead of voice commands.


Testing Smart & Manual Home Automation with Alexa & ESP32 
Now that the relays are set up in the Alexa app, you can control them and turn on with voice commands. For example:
“Alexa, turn on Relay 1.”
“Alexa, turn on Relay 2.”
“Alexa, turn on Relay 3.”
“Alexa, turn on Relay 4.”
To turn off the Relays, you can control them with the voice command as:
“Alexa, turn off Relay 1.”
“Alexa, turn off Relay 2.”
“Alexa, turn off Relay 3.”
“Alexa, turn off Relay 4.”
Alternatively, you can manually control them through the Alexa app by tapping on the device and using the on-screen toggle.
You may press the manual push buttons to turn the on/off the Relays. While pressing the push button, the relays will toggle.
We did something great here! We combined normal home switches with Alexa’s voice power using ESP32 . The neat part? If you lose WiFi, you can still flip the switches by hand. With this project, we’re mixing old ways with new tech to make our homes smarter and simpler to use.

Search This Blog

The Transparent Car