Wiring Diagrams¶

Complete wiring reference for the IoT Toolkit.

Master Wiring Diagram

ESP32 Pinout Reference¶

DevKit V1 (30-pin) Layout¶

          EN          GPIO23    GPIO22    GPIO1     GPIO3     GPIO21    GPIO19    GPIO18    GPIO5     GPIO17    GPIO16    GPIO4     GPIO0     GPIO2     GPIO15    GPIO13    GPIO12    GPIO14    GPIO27    GPIO26    GPIO25    GPIO33    GPIO32    GPIO35    GPIO34    GPIO39    GPIO36    VCC       GND
           |            |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |
    [ESP32 DevKit Board]
           |            |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |         |
          RST          GPIO23    GPIO22    TX0       RX0       GPIO21    GPIO19    GPIO18    GPIO5     GPIO17    GPIO16    GPIO4     GPIO0     GPIO2     GPIO15    GPIO13    GPIO12    GPIO14    GPIO27    GPIO26    GPIO25    GPIO33    GPIO32    GPIO35    GPIO34    GPIO39    GPIO36    3.3V      GND

Complete System Wiring¶

Overview Diagram¶

                              +-------------------+
                              |     ESP32         |
                              |                   |
        +---------------------+ GPIO21 (SDA)      +---------------------+
        |                     | GPIO22 (SCL)      |                     |
        |                     | GPIO18 (SCK)      |                     |
        |                     | GPIO19 (MISO)     |                     |
        |                     | GPIO23 (MOSI)     |                     |
        |                     | GPIO5 (CS)          |                     |
        |                     | 3.3V / GND        |                     |
        |                     +-------------------+                     |
        |                                                               |
        |           I2C Bus                          SPI Bus            |
        +---------------+                          +----------+         |
        |               |                          |          |         |
   +----+----+    +-----+----+    +--------+   +---+--+   +--+---+      |
   | Temp    |    | Humidity |    | I2C    |   | TFT  |   |     |       |
   | Sensor  |    | Sensor   |    | Mux    |   | Disp |   |     |       |
   +---------+    +----------+    +--------+   +------+   +-----+       |
                                                                          |
   +---------+    +----------+    +--------+   +------+                    |
   | Vib     |    | Acoustic |    | Voice  |   | LCD  |                   |
   | Sensor  |    | Sensor   |    | Module |   | Disp |                   |
   +---------+    +----------+    +--------+   +------+                   |
                                                                          |
   +------------------+                                                   |
   | Camera Module    |                                                   |
   | (ESP32-CAM)      |                                                   |
   +------------------+                                                   |

Detailed Connections¶

I2C Bus (GPIO21=SDA, GPIO22=SCL)¶

Device	SDA	SCL	VCC	GND	Notes
Temperature Sensor	GPIO21	GPIO22	3.3V	GND
Humidity Sensor	GPIO21	GPIO22	3.3V	GND
Vibration Sensor	GPIO21	GPIO22	3.3V	GND
Acoustic Sensor	GPIO21	GPIO22	3.3V	GND
LCD Display	GPIO21	GPIO22	3.3V/5V	GND	I2C backpack
I2C Multiplexer	GPIO21	GPIO22	3.3V	GND	TCA9548A
Voice Module	GPIO21	GPIO22	3.3V/5V	GND

SPI Bus (TFT Display)¶

TFT Pin	ESP32 Pin	Notes
VCC	3.3V	Power
GND	GND	Ground
SCK	GPIO18	SPI Clock
MISO	GPIO19	SPI MISO
MOSI	GPIO23	SPI MOSI
CS	GPIO5	Chip Select
DC		Data/Command
RST		Reset
LED	3.3V	Backlight (or PWM)

I2C Multiplexer Channels¶

TCA9548A Multiplexer
       |
       |-- SD0/SC0 --> [Channel 0 Device]
       |-- SD1/SC1 --> [Channel 1 Device]
       |-- SD2/SC2 --> [Channel 2 Device]
       |-- SD3/SC3 --> [Channel 3 Device]
       |-- SD4/SC4 --> [Channel 4 Device]
       |-- SD5/SC5 --> [Channel 5 Device]
       |-- SD6/SC6 --> [Channel 6 Device]
       |-- SD7/SC7 --> [Channel 7 Device]

Camera Module (ESP32-CAM)¶

ESP32-CAM uses dedicated pins. Connect separately:

Function	GPIO	Notes
Power	3.3V	-
Ground	GND	-
U0TXD	GPIO1	Serial TX
U0RXD	GPIO3	Serial RX
Flash	GPIO4	LED control
PSRAM	GPIO16	External RAM
Camera	Multiple	Fixed assignment

Power Distribution¶

3.3V Rail¶

ESP32 (internal)
All I2C sensors
TFT display
I2C multiplexer
Voice module (if 3.3V)

5V Rail (if using 5V LCD)¶

LCD Display (with I2C backpack)
Voice module (if 5V)

Power Budget Estimate¶

Component	Current	Voltage
ESP32 (active)	120-250mA	3.3V
Temperature Sensor	~1mA	3.3V
Humidity Sensor	~1mA	3.3V
Vibration Sensor	~1-5mA	3.3V
Acoustic Sensor	~1mA	3.3V
LCD Display	~10mA	3.3V/5V
TFT Display	~50mA	3.3V
I2C Multiplexer	~1mA	3.3V
Voice Module	~20-50mA	3.3V/5V
Camera Module	~100mA	3.3V
Total	~300-500mA	-

Breadboard Layout¶

Recommended Arrangement¶

Breadboard Layout (830 tie points)

[Top Power Rails]
Red (+):    3.3V from ESP32 --------------------------->
Blue (-):   GND  --------------------------------------->

[Component Row 1-10]
ESP32 DevKit (across center divider)

[Component Row 11-20]
I2C Multiplexer
Temperature Sensor
Humidity Sensor
Vibration Sensor
Acoustic Sensor

[Component Row 21-30]
LCD Display (I2C)
TFT Display (SPI)
Voice Module
Camera Module (separate or at end)

[Bottom Power Rails]
Red (+):    5V (if needed) ----------------------------->
Blue (-):   GND  --------------------------------------->

Wire Colors (Recommended)¶

Color	Purpose
Red	3.3V / 5V Power
Black	Ground
Yellow	I2C SDA
White	I2C SCL
Blue	SPI SCK
Green	SPI MOSI
Orange	SPI MISO
Purple	SPI CS
Gray	Other GPIO

Pull-up Resistors¶

I2C requires pull-up resistors on SDA and SCL:

4.7kΩ recommended for 3.3V I2C
Many modules include pull-ups
Add external resistors if communication is unstable

3.3V ----[4.7kΩ]----+---- SDA (GPIO21)
                    |
3.3V ----[4.7kΩ]----+---- SCL (GPIO22)

Testing Connections¶

I2C Scanner¶

Upload I2C scanner to verify all I2C devices:

#include <Wire.h>

void setup() {
  Wire.begin();
  Serial.begin(115200);
  Serial.println("\nI2C Scanner");
}

void loop() {
  Serial.println("Scanning...");

  for (byte address = 1; address < 127; address++) {
    Wire.beginTransmission(address);
    if (Wire.endTransmission() == 0) {
      Serial.print("I2C device at 0x");
      if (address < 16) Serial.print("0");
      Serial.println(address, HEX);
    }
  }

  Serial.println("Done\n");
  delay(5000);
}

Troubleshooting¶

Issue	Check
Device not detected	Verify I2C address, check wiring, test with multimeter
Intermittent connection	Check loose wires, add pull-up resistors
SPI display blank	Verify CS pin, check initialization sequence
Brownouts	Add capacitor (100μF) near power pins
I2C conflicts	Use multiplexer, verify unique addresses

Next Steps¶

Set up individual sensors
Configure displays
Proceed to software setup