Unit G - ESP32 Foundations

34. Introducing the ESP32 Family

Meet the ESP32 family, learn classic DevKit anatomy, install Espressif support, and complete a reliable first blink/Serial upload.

Estimated time 2-3 hours

Learning outcomes

Explain how ESP32-class boards differ from Arduino Uno R3
Identify EN, BOOT, USB, 3V3/GND/5V and GPIO headers on a classic DevKit
Compare classic ESP32, ESP32-C3, ESP32-C5, ESP32-C6 and ESP32-P4 at a high level
Add the Espressif ESP32 board package and select ESP32 Dev Module for course labs
Upload a first sketch, open Serial at 115200, and fix common port/BOOT faults
Apply 3.3 V I/O safety and know what Units G-I cover next

Parts and preparation

Arduino IDE 2, USB data cable (not charge-only), and one ESP32-family board. Course practicals default to a classic ESP32 DevKit (ESP32 Dev Module). C3/C5/C6/P4 are fine for this intro if you pick the matching Board menu entry.

Before power: inspect wiring, confirm supply voltage and ensure all connected circuits share GND.

Introducing the ESP32 Family instructional connection diagram

What is the ESP32 family?

ESP32 is a family of microcontrollers from Espressif. Most members are used for Wi-Fi and Bluetooth projects; ESP32-P4 is the high-performance HMI / edge-compute branch and does not include on-chip Wi-Fi or Bluetooth. You still program them from Arduino IDE 2, but with the Espressif board package instead of the Uno AVR core.

Units A-F stay the foundation for pins, sketches and safe wiring. Units G-I extend that skill set for 3.3 V practice, NeoPixel displays, Wi-Fi, MQTT, BLE, sleep and OTA.

Path from lesson 34 through Unit G then Units H and I — 34 unlocks the board. Next: architecture, 3.3 V, pins, NeoPixel, then wireless and advanced topics.

Course default board

Unless a lesson says otherwise, Unit G-I practicals assume a classic ESP32 DevKit and the IDE entry Tools -> Board -> esp32 -> ESP32 Dev Module.

C3, C5, C6 and P4 boards are part of the family overview so you can recognise them in shops and datasheets. Their GPIO maps and Board menu names differ - if you use one for labs, match the silkscreen and board definition carefully.

Item	Course habit
Default practical board	Classic ESP32 DevKit / WROOM class
IDE Board entry	ESP32 Dev Module
Serial baud	115200
Logic class	3.3 V GPIO - never feed 5 V into pins
Other SoCs (C3/C5/C6/P4)	Know the family; pick matching Board entry if that is your hardware

Classic DevKit anatomy

A typical 30- or 38-pin DevKit is more than the metal-can module. Trace these parts on your board before the first upload:

USB connector and USB-to-serial chip (needs a data cable). EN (reset/enable) and BOOT buttons. 3V3, GND and 5V/VIN pins. Two rows of GPIO headers labelled with GPIO numbers - not Uno D0-D13 numbers.

Many DevKits put the blue on-board LED on GPIO 2. If Blink does nothing, check the silkscreen before rewriting the sketch.

Classic ESP32 DevKit showing USB, EN, BOOT, power pins and GPIO headers — Find EN, BOOT, USB, 3V3/GND/5V and GPIO labels on your silkscreen.

ESP32 versus Arduino Uno R3

Same IDE workflow idea (setup/loop), very different hardware. Treat voltage and pin maps carefully when you switch boards.

Feature	Arduino Uno R3	Typical ESP32-family board
Maker / MCU	Arduino / ATmega328P (8-bit AVR)	Espressif / ESP32-class SoC
CPU class	16 MHz single core	Much faster; Xtensa or RISC-V (single- or dual-core)
Memory	32 KB Flash, 2 KB SRAM	Megabytes of Flash, hundreds of KB SRAM (varies by module)
Logic voltage	5 V I/O	3.3 V I/O - do not feed 5 V into pins
Wi-Fi / Bluetooth	None on-board	Most chips: Wi-Fi and usually Bluetooth; ESP32-P4 needs a companion radio for wireless
ADC	6 x 10-bit (A0-A5)	Multiple ADC channels; check the module pinout
USB / programming	USB-B serial bridge	USB-UART or native USB-C (board-dependent)
IDE support	Arduino AVR Boards	esp32 by Espressif Systems (Board Manager)
Shields / 5 V modules	Uno ecosystem	Often need level shifting or 3.3 V-safe modules

Classic ESP32 (DevKit / WROOM class)

The original ESP32 (often sold as ESP32-DevKitC or ESP32-WROOM modules) uses Xtensa dual-core CPUs with 2.4 GHz Wi-Fi and Bluetooth Classic/BLE. It is the most common "ESP32" learners mean, and the default for later course sketches. The example photo is a common 38-pin DevKit V1 style board (ESP-WROOM-32, Micro-USB).

Classic ESP32 DevKit V1 38-pin development board — Classic ESP32 DevKit / WROOM example - confirm GPIO numbers on your silkscreen; pick ESP32 Dev Module in the IDE.Photo: Mantech ESP-32-38-PIN.

ESP32-C3

ESP32-C3 is a cost-focused RISC-V single-core chip with 2.4 GHz Wi-Fi 4 and Bluetooth LE. It is a strong budget step into Wi-Fi when you do not need the dual-core classic ESP32 or Thread/Zigbee radios. The example photo is a Waveshare ESP32-C3-Zero - a compact USB-C board; always match the IDE board entry and GPIO labels to your module.

ESP32-C5

ESP32-C5 adds dual-band Wi-Fi 6 (2.4 GHz and 5 GHz) plus Bluetooth LE and IEEE 802.15.4 (useful for Matter / Thread-style IoT). Choose C5 when 5 GHz Wi-Fi or dual-band connectivity matters. The example photo is a Waveshare ESP32-C5-WIFI6-KIT (N16R4 class module).

ESP32-C6

ESP32-C6 is a RISC-V IoT SoC with 2.4 GHz Wi-Fi 6, Bluetooth LE, and IEEE 802.15.4 for Zigbee / Thread / Matter-oriented designs. It is a common choice for modern smart-home nodes that need Wi-Fi 6 and 802.15.4 without 5 GHz. The example photo is a DFRobot FireBeetle 2 ESP32-C6.

ESP32-P4

ESP32-P4 is Espressif's high-performance RISC-V SoC for rich human-machine interfaces and edge compute: dual-core CPU, MIPI-CSI camera and MIPI-DSI display paths, USB 2.0 HS, and media helpers such as H.264 encode. The P4 itself has no on-chip Wi-Fi or Bluetooth - many boards add a companion radio (often an ESP32-C6). The example photo is a DFRobot FireBeetle 2 ESP32-P4 with onboard MIPI CSI/DSI and a C6 co-processor for Wi-Fi 6. Choose P4 for displays, cameras and heavier local processing; choose a C-series or classic ESP32 when you only need a simple Wi-Fi node.

ESP32 versions at a glance

High-level comparison for course selection. Exact Flash/SRAM and pin counts depend on the module and vendor board.

SoC	CPU	Wi-Fi	Bluetooth	802.15.4 / Matter-oriented	Typical use
ESP32 (classic)	Xtensa dual-core	Wi-Fi 4 (2.4 GHz)	BT Classic + BLE	No	Course default for Wi-Fi labs; largest community examples
ESP32-C3	RISC-V single-core	Wi-Fi 4 (2.4 GHz)	BLE	No	Budget Wi-Fi + BLE nodes
ESP32-C5	RISC-V	Wi-Fi 6 dual-band (2.4 + 5 GHz)	BLE	Yes (IEEE 802.15.4)	Dual-band / 5 GHz Wi-Fi IoT
ESP32-C6	RISC-V single-core	Wi-Fi 6 (2.4 GHz)	BLE	Yes (Zigbee/Thread/Matter path)	Smart-home / Matter-class nodes
ESP32-P4	RISC-V dual-core (high perf.)	No on-chip (companion radio)	No on-chip (companion radio)	Via companion if fitted	HMI, MIPI camera/display, edge compute

Add ESP32 support in Arduino IDE 2

Install Espressif's official board package once. Verify compiles on the PC; Upload sends the binary through the selected port. Wrong Board entry is a common cause of confusing upload failures.

Steps: Espressif package, ESP32 Dev Module, port, Verify then Upload, Serial 115200, BOOT if needed — Package -> Board -> Port -> Verify -> Upload. Serial Monitor at 115200.

Step	Action
1	File -> Preferences (Windows/Linux) or Arduino IDE -> Settings (macOS)
2	Additional Board Manager URLs: https://espressif.github.io/arduino-esp32/package_esp32_index.json
3	Boards Manager: search esp32; install esp32 by Espressif Systems
4	Tools -> Board -> esp32 -> ESP32 Dev Module (or your matching C3/C5/C6/P4 entry)
5	Tools -> Port -> the COM/tty device that appears when the board is plugged in
6	Verify, then Upload this lesson sketch; open Serial Monitor at 115200

Upload faults and the BOOT button

If Upload cannot connect: use a USB data cable, try another USB socket, and confirm the port appears only when the board is plugged in.

On many classic DevKits, hold BOOT, start Upload, then release BOOT when the tool begins writing. EN resets the board - useful after a stuck upload or to replay Serial startup messages.

Symptom	Likely fix
No port listed	Data cable; drivers; another USB socket
Wrong board	ESP32 Dev Module for classic DevKit - not Uno
Upload timed out	Hold BOOT during connect; release when writing
Blank Serial	Baud 115200; press EN/RESET after open
LED never blinks	Confirm LED_BUILTIN / GPIO 2 on your silkscreen

3.3 V safety when leaving the Uno

ESP32-family GPIO is 3.3 V. Never connect a 5 V Uno output directly into an ESP32 input. Many "5 V" sensors need level shifting or a 3.3 V-safe variant. USB often feeds 5 V into the DevKit regulator while chip I/O stays 3.3 V - lesson 36 goes deeper on rails and dividers.

Wiring and safe build sequence

Connect the ESP32 with a USB data cable (not charge-only)
Install esp32 by Espressif Systems using the Board Manager steps in this lesson
Tools -> Board -> ESP32 Dev Module (classic DevKit) and select the correct port
Locate EN, BOOT, 3V3, GND and the on-board LED (often GPIO 2) on your silkscreen
Upload this sketch; open Serial Monitor at 115200
If using an external LED: series resistor, safe GPIO, common GND; keep logic 3.3 V-compatible

Power rule: switch off before moving wires. Arduino I/O pins are control signals; high-current loads require a driver and suitable external supply.

Worked sketch

Download .ino sketch

#ifndef LED_BUILTIN
#define LED_BUILTIN 2
#endif

const int ledPin = LED_BUILTIN;

void setup() {
  pinMode(ledPin, OUTPUT);
  Serial.begin(115200);
  delay(500);
  Serial.println("ESP32 ready - Serial at 115200");
}

void loop() {
  digitalWrite(ledPin, HIGH);
  Serial.println("LED on");
  delay(500);
  digitalWrite(ledPin, LOW);
  Serial.println("LED off");
  delay(500);
}

How the code works

Match Serial Monitor to 115200 - Uno examples often used 9600.
LED_BUILTIN is often GPIO 2 on classic DevKits; change ledPin if your board differs.
Upload uses the Espressif toolchain from Board Manager, not the Uno AVR core.
A short delay after Serial.begin gives the USB-serial bridge time before the first print.

Test and record evidence

Expected result: The sketch uploads. Serial prints a ready line then LED on/off messages. The on-board or wired LED blinks if ledPin matches the board.

Practical evidence checklist

Labelled wiring or block diagram Uploaded sketch and observed result At least one measured/tested value Fault or improvement recorded in logbook

Common faults and checks

Board package missing: confirm the Additional Board Manager URL and install esp32 by Espressif Systems.
Wrong board selected: classic DevKit needs ESP32 Dev Module; C3/C5/C6/P4 need their own entries.
No port: data cable, drivers, or another USB socket.
Upload fails at connect: hold BOOT while uploading on some boards, then release.
Blank Serial: set 115200 and press EN/RESET.
LED silent: set ledPin to the GPIO labelled for the on-board LED.
P4 board has no Wi-Fi in sketches: expected unless a companion radio is fitted and configured.

Extension challenge: On your board photo or silkscreen, point to EN, BOOT, USB, 3V3, GND and one GPIO. Write down the IDE Board menu name you used and one measured 3.3 V rail reading to GND.

Check your understanding

Q1. What is the course default Board menu entry for classic DevKit labs?

Show answer

ESP32 Dev Module.

Q2. What Serial baud do ESP32 course sketches use?

Show answer

115200.

Q3. Name two parts to find on a classic DevKit besides the metal module.

Show answer

Examples: EN, BOOT, USB, 3V3, GND, 5V/VIN, GPIO headers.

Q4. What is the usual I/O voltage class for ESP32 pins compared with Uno R3?

Show answer

ESP32 is 3.3 V; Uno R3 is 5 V.

Q5. What Board Manager package author should you install for ESP32?

Show answer

Espressif Systems (package name esp32).

Q6. What should you try if Upload cannot connect on a classic DevKit?

Show answer

Hold BOOT during connect, then release when writing starts; also check data cable and port.

Q7. Why might a 5 V sensor output be unsafe on ESP32?

Show answer

It can over-voltage a 3.3 V GPIO without level shifting.

Q8. What is ESP32-P4 mainly for, and what does it lack on-chip?

Show answer

HMI / camera-display / edge compute; no on-chip Wi-Fi or Bluetooth.