ESP32 Setup¶

ESP32 WROOM

The ESP32 is the heart of the IoT Toolkit - a powerful WiFi-enabled microcontroller that connects all sensors to the cloud.

Overview¶

The ESP32 provides: - Dual-core processor (up to 240MHz) - Built-in WiFi (802.11 b/g/n) - Bluetooth (optional) - Multiple GPIO pins - ADC, DAC, PWM, I2C, SPI, UART support

Specifications¶

Feature	Specification
Processor	Dual-core Xtensa LX6
Clock Speed	Up to 240MHz
RAM	520KB SRAM
Flash	4MB (typical)
WiFi	802.11 b/g/n
GPIO	34 programmable pins
ADC	12-bit, 18 channels
DAC	8-bit, 2 channels
Operating Voltage	3.3V
Input Voltage	5V (via USB) or 3.3V

Pinout Diagram¶

          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

Key Pin Assignments¶

Pin	Function	Common Use
GPIO21	I2C SDA	Default I2C data
GPIO22	I2C SCL	Default I2C clock
GPIO18	SPI SCK	SPI clock
GPIO19	SPI MISO	SPI data in
GPIO23	SPI MOSI	SPI data out
GPIO5	SPI CS	SPI chip select
GPIO0	Boot	Boot mode (don't pull low on boot)
GPIO2	Boot	Boot mode (must be floating or pulled high)
TX0 (GPIO1)	UART TX	Serial output
RX0 (GPIO3)	UART RX	Serial input

Arduino IDE Setup¶

1. Install ESP32 Board Support¶

Follow the Prerequisites guide to install ESP32 support in Arduino IDE.

2. Select Board Configuration¶

In Arduino IDE:

Tools > Board > ESP32 Arduino > ESP32 Dev Module

3. Serial Port Selection¶

Select the correct COM port:

Tools > Port > COMx (or /dev/ttyUSB0 on Linux)

4. Upload Settings¶

Setting	Value	Description
Upload Speed	921600	Fast upload
CPU Frequency	240MHz	Maximum speed
Flash Frequency	80MHz	Flash access speed
Flash Mode	QIO	Quad I/O mode
Flash Size	4MB	Standard flash size
Partition Scheme	Default 4MB	Partition layout

First Sketch¶

Blink Test¶

Verify your ESP32 is working:

// ESP32 Blink Test
// LED is on GPIO2 for most ESP32 DevKits

#define LED_BUILTIN 2

void setup() {
  pinMode(LED_BUILTIN, OUTPUT);
  Serial.begin(115200);
  Serial.println("ESP32 starting...");
}

void loop() {
  digitalWrite(LED_BUILTIN, HIGH);
  Serial.println("LED ON");
  delay(1000);

  digitalWrite(LED_BUILTIN, LOW);
  Serial.println("LED OFF");
  delay(1000);
}

Expected Output¶

In Serial Monitor (115200 baud):

ESP32 starting...
LED ON
LED OFF
LED ON
LED OFF
...

And the on-board LED should blink.

WiFi Connection Test¶

Test WiFi connectivity:

#include <WiFi.h>

const char* ssid = "YOUR_WIFI_SSID";
const char* password = "YOUR_WIFI_PASSWORD";

void setup() {
  Serial.begin(115200);

  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

void loop() {
  // Connection maintained automatically
}

Power Considerations¶

Power Supply Options¶

Method	Voltage	Current	Use Case
USB	5V	500mA	Development
External 3.3V	3.3V	500mA+	Production
LiPo Battery	3.7V	Varies	Portable

Power Consumption¶

Mode	Current	Notes
Active (WiFi)	120-250mA	Normal operation
Active (no WiFi)	50-100mA	Processing only
Modem Sleep	20mA	WiFi off, CPU on
Light Sleep	2mA	CPU paused
Deep Sleep	10μA	Wake on timer/GPIO

Common GPIO Usage¶

This toolkit uses:

GPIO	Purpose	Connected To
GPIO21	I2C SDA	All I2C sensors
GPIO22	I2C SCL	All I2C sensors
GPIO18	SPI SCK	TFT display
GPIO19	SPI MISO	TFT display
GPIO23	SPI MOSI	TFT display
GPIO5	SPI CS	TFT display

Troubleshooting¶

Issue	Solution
Upload fails	Hold BOOT button, press RESET, release BOOT
No serial output	Check baud rate (115200), verify TX/RX
GPIO not working	Verify pin is not input-only (GPIOs 34-39)
WiFi won't connect	Check credentials, verify 2.4GHz network
Brownouts	Increase power supply capacity

Next Steps¶

Once ESP32 is working:

Connect sensors
Add displays
Configure cloud connectivity

ESP32 Variants

This guide works with any ESP32-WROOM-32 based board. Other variants (ESP32-S2, ESP32-C3, ESP32-S3) may have different pinouts.