EFZ-ESP32S3

Board Overview

EFZ-ESP32S3 — front and back

Name

efz_esp32s3

Vendor

EmbeddedFun

Architecture

xtensa

SoC

esp32s3

Browse board sourcesDownload schematic (PDF)

The EFZ-ESP32S3 is the EmbeddedFun training board: an ESP32-S3 with every peripheral the course uses already on board.

Resources

Design files

Revision	Schematic	Notes
V1	EFZ-ESP32S3-V1-schematic.pdf (PDF, 9 sheets)	See the Rev 1 errata

Zephyr board support

• Build target: efz_esp32s3/esp32s3/procpu (hardware model v2, vendor embeddedfun).

• Board files: devicetree, pinctrl, Kconfig and defconfig in boards/embeddedfun/efz_esp32s3, with the board's Zephyr documentation page in doc/index.rst.

• Get it: create a workspace from the fork, as in Environment Setup & West:

  west init -m https://github.com/huunghiaspkt/zephyr --mr main /your/workspace/path

Lessons

The whole Zephyr RTOS course runs on this board; every hands-on page has an EFZ-ESP32S3 tab. Good places to start:

Lesson	On this board
Environment Setup & West	Install the tools, build, flash over USB-C and read the console
WS2812 RGB LED	The on-board RGB LED on GPIO21, added with an overlay
Sensors	The on-board SHT30 temperature and humidity sensor on I2C
WiFi · WiFi Shell	The ESP32-S3 radio: connect and scan
BLE Basics	Bluetooth LE from the ESP32-S3
Devicetree · Writing Overlays · Custom Board Support	How this board is described to Zephyr
Write & Run Your First Test	Unit tests with ztest and Twister

Examples

Ready-to-build samples for this board live in samples/efz_samples of the Zephyr fork. Build any of them from your workspace folder:

west build -b efz_esp32s3/esp32s3/procpu zephyr/samples/efz_samples/02_basic/led_strip -p
west flash

• 01_how-to-start/hello_world — Hello World on the USB console
• 02_basic/led_strip — The on-board WS2812 RGB LED
• 02_basic/threads_basic — Two threads running side by side
• 03_intermediate/i2c_sensor — The SHT30 temperature and humidity sensor
• 03_intermediate/devicetree_tour — Reading the board's devicetree from C
• 03_intermediate/kconfig_demo — Kconfig options in an application
• 03_intermediate/binding_yaml — A devicetree binding of your own
• 03_intermediate/custom_driver — An out-of-tree driver
• 03_intermediate/power_management — Device power management
• 03_intermediate/threads_sync — Thread synchronisation
• 03_intermediate/ble_basics — Bluetooth LE
• 04_advanced/wifi_shell — Wi-Fi from the Zephyr shell
• 05_ztest/ztest_calc · 05_ztest/pytest_calc — ztest and pytest under Twister
• displays/alignment_test — A test pattern for a TFT on the display connector

Compatible

• Zephyr: the EmbeddedFun Zephyr fork (main), which is upstream Zephyr plus this board
• Host OS: Linux, macOS (Apple Silicon) and Windows; the Environment Setup steps are tested on all three every week
• Flashing and console: west flash over the USB-C cable (native USB Serial/JTAG); no separate programmer
• Displays: 1.47" ST7789V3 172×320 SPI TFT on the display connector, with its overlay in the fork
• Your own modules: 3.3 V parts on the I2C, UART and SPI headers; pins in Connections and IOs
• Other boards: the course also runs on Espressif's ESP32-S3-DevKitC, with modules wired to it

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Overview

The EFZ-ESP32S3 puts an ESP32-S3 on a compact board together with the parts an embedded course needs: a temperature and humidity sensor, a 6-axis IMU, an RGB LED, a microphone, a speaker amplifier, a microSD slot, a display on the back, and headers for your own wiring. It is powered, flashed and debugged over a single USB-C cable.

Hardware

ESP32-S3 features

ESP32-S3 is a low-power MCU-based system on a chip (SoC) with integrated 2.4 GHz Wi-Fi and Bluetooth Low Energy. It has a high-performance dual-core Xtensa 32-bit LX7 microprocessor, a low-power coprocessor, a Wi-Fi baseband, a Bluetooth LE baseband, an RF module and numerous peripherals.

• Dual-core 32-bit Xtensa LX7, up to 240 MHz, with vector instructions for AI acceleration
• 512 KB SRAM, 384 KB ROM
• Wi-Fi 802.11 b/g/n
• Bluetooth LE 5.0 with long range, up to 2 Mbps

Digital interfaces: 45 programmable GPIOs · 4× SPI · 3× UART · 2× I2C · 2× I2S · LCD interface · DVP camera interface · RMT · pulse counter · LED PWM (8 channels) · full-speed USB OTG · USB Serial/JTAG · 2× MCPWM · SDIO host (2 slots) · GDMA (5 TX + 5 RX channels) · TWAI (CAN 2.0)

Analog interfaces: 2× 12-bit SAR ADC (up to 20 channels) · temperature sensor · 14 touch-sensing IOs

Timers: 4× 54-bit general-purpose timers · 52-bit system timer · 3× watchdog timers

Low power: power management unit with five power modes · ULP-RISC-V and ULP-FSM coprocessors

Security: secure boot · flash encryption · 4-Kbit OTP · AES, SHA, RSA, RNG, HMAC and digital-signature accelerators

On this board the chip has no in-package flash or PSRAM: code runs from an external 8 MB QSPI flash (EN25QH64A).

Board components

Feature	Detail
MCU	ESP32-S3 (QFN56, no in-package flash or PSRAM) — dual-core Xtensa LX7 @ 240 MHz, 512 KB SRAM
Operating temp.	–40 to 105 °C ambient (chip rating)
Flash	8 MB external QSPI (EN25QH64A)
Wireless	Wi-Fi 802.11 b/g/n + Bluetooth LE 5.0, chip antenna
USB	USB-C, wired straight to the ESP32-S3's native USB — flashing and console
Power	5 V USB → 1117-type 3.3 V LDO, red power LED
Sensors	SHT30 temperature/humidity, MPU-6500 6-axis IMU, NTC thermistor input
Audio	INMP441 I2S microphone, MAX98357A I2S class-D amp (speaker header)
Storage	microSD, 4-bit SDIO with card-detect
User I/O	1× WS2812B RGB LED, 2× red LEDs, 2× user buttons,BOOT and RESET buttons
Display	Rounded TFT on the back (SPI) — driver added per display module, via overlay
Expansion	Two 7-pin headers; I2C, UART, NTC and speaker connectors

Supported features

Generated from the board's devicetree: every node the EFZ-ESP32S3 enables, with its binding. The count shows how many nodes of that kind are enabled; the compatible links to its binding in the Zephyr docs.

Type	Location	Description	Compatible
ADC	on-chip	ESP32 ADC×1	espressif,esp32-adc
Bluetooth	on-chip	Bluetooth HCI for Espressif ESP32×1	espressif,esp32-bt-hci
CPU	on-chip	Espressif Xtensa LX7 CPU×2	espressif,xtensa-lx7
Clock control	on-chip	ESP32 Clock (Power & Clock Controller Module) Module×1	espressif,esp32-clock
Counter	on-chip	ESP32 general-purpose timers×1	espressif,esp32-timer
Crypto	on-chip	Espressif ESP32 family AES Hardware Accelerator×1	espressif,esp32-aes
Crypto	on-chip	Espressif ESP32 SHA Hardware Accelerator×1	espressif,esp32-sha
DMA	on-chip	ESP32 GDMA (General Direct Memory Access)×1	espressif,esp32-gdma
Entropy	on-chip	ESP32 TRNG (True Random Number Generator)×1	espressif,esp32-trng
Flash	on-chip	Flash node×1	soc-nv-flash
Flash controller	on-chip	ESP32 flash controller×1	espressif,esp32-flash-controller
GPIO	on-chip	ESP32 GPIO controller×2	espressif,esp32-gpio
I2C	on-chip	ESP32 I2C×1	espressif,esp32-i2c
I2S	on-chip	ESP32 I2S×1	espressif,esp32-i2s
Input	on-board	Group of GPIO-bound input keys×1	gpio-keys
Interrupt controller	on-chip	ESP32 Interrupt controller×1	espressif,esp32-intc
LED	on-board	Group of GPIO-controlled LEDs×1	gpio-leds
Miscellaneous	on-chip	ESP32 LCD-CAM controller×1	espressif,esp32-lcd-cam
Pin control	on-chip	ESP32 pin controller×1	espressif,esp32-pinctrl
SD	on-board	Zephyr SDMMC disk (microSD slot)×1	zephyr,sdmmc-disk
SD host controller	on-chip	ESP32 SDHC controller×1	espressif,esp32-sdhc
SD host controller	on-chip	ESP32 SDHC controller slot×1	espressif,esp32-sdhc-slot
Sensor	on-board	MPU-6000 motion tracking device (MPU-6500 on this board)×1	invensense,mpu6050
Sensor	on-board	Sensirion Humidity SHT3x-DIS humidity and temperature sensor (SHT30 on this board)×1	sensirion,sht3xd
Serial controller	on-chip	ESP32 UART×1	espressif,esp32-uart
Serial controller	on-chip	ESP32 UART (USB Serial/JTAG console)×1	espressif,esp32-usb-serial
Watchdog	on-chip	ESP32 watchdog×1	espressif,esp32-watchdog
Wi-Fi	on-chip	ESP32 SoC Wi-Fi×1	espressif,esp32-wifi

Connections and IOs

The back holds the display and labels every connector — handy when you're wiring something up with the board face down. Here it is without the display fitted, so you can see the display outline and its FPC pads:

The back, display not fitted

Function	Part	ESP32-S3 pins	Notes
USB	native USB Serial/JTAG	D− GPIO19, D+ GPIO20	flashing + console
UART0	box header P6	TX GPIO43, RX GPIO44	free for your own use
I2C (shared)	SHT30 @ 0x44	SDA GPIO17, SCL GPIO18	also on box header P5
	MPU-6500 @ 0x69	same bus, INT → GPIO48
ADC	NTC 10 kΩ B3950 (header P7)	GPIO1 (ADC1_CH0)	10 kΩ pull-up to 3V3
RGB LED	WS2812B	GPIO21
LEDs	LED1, LED2 (red)	GPIO46, GPIO45	active-high
Buttons	BOOT, RESET	GPIO0, CHIP_PU	BOOT is usable as a button
microSD	4-bit SDIO	CLK 9, CMD 10, D0 8, D1 7, D2 12, D3 11, CD 6
Microphone	INMP441 (left channel)	BCLK 2, WS 4, DOUT 3, EN 5
Speaker	MAX98357A	BCLK 34, DATA 33, WS 35, SD 47	SD low (10 kΩ pull-down) keeps the amp off
Buttons	BN1, BN2	GPIO36, GPIO37	active-low, 10 kΩ pull-up
TFT	SPI display connector	SCL 40, SDA 41, CS 39, DC 38, RST 42, BLK 16	shares header P4
Header P4	7-pin	3V3, GPIO42, 41, 40, 39, 38, GND
Header P3	7-pin	3V3, GPIO26, 16, 15, 14, 13, GND	silkscreen differs — see errata

The TFT and header P4 share pins

GPIO38–42 go to both the TFT connector and header P4, and GPIO16 (backlight) is on header P3. With a display plugged in, don't use those header pins for anything else.

Strapping pins

The ESP32-S3 samples four pins at reset and latches them until power-off; after that they're ordinary GPIOs. This board uses all four, safely:

Pin	Controls	Chip default	On this board	Result
GPIO0	boot mode	weak pull-up → 1	BOOT button + 10 kΩ pull-up	runs from flash; hold BOOT for download mode
GPIO46	boot mode, ROM log	weak pull-down → 0	LED1 + 1 kΩ to GND	0, as download mode requires
GPIO45	VDD_SPI voltage	weak pull-down → 0	LED2 + 1 kΩ to GND	0 → 3.3 V, which the EN25QH64A flash needs
GPIO3	JTAG source	floating	INMP441 data out	ignored unless the STRAP_JTAG_SEL eFuse is burned (it isn't by default)

Never pull GPIO45 high at reset

GPIO45 = 1 at reset switches VDD_SPI to 1.8 V. The 3.3 V flash then can't be read and the board won't boot. If you hang anything on LED2's pin, keep it low (or high-impedance) during reset.

Source: ESP32-S3 datasheet, §3, Tables 3-1 to 3-5.

Which free pins are safe?

Besides the strapping pins, the datasheet ranks GPIOs by how freely you can use them (§2.3.5). Here's how that plays out on this board:

Pins	Status on EFZ-ESP32S3
GPIO13, 14, 15, 26	free on header P3 — use these first
GPIO16	free on header P3 unless a TFT is fitted (it's the backlight)
GPIO38–42	on header P4, shared with the TFT. GPIO39–42 are also the chip's pad-JTAG pins; that's fine, since JTAG debugging goes over USB on this board
GPIO43, 44	UART0 on box header P6. The ROM prints its boot log here too
GPIO15, 16	can also take an external 32 kHz crystal (XTAL_32K) — not fitted on Rev 1
GPIO26	also SPICS1, the chip-select for an optional external PSRAM — none is fitted, so it's an ordinary GPIO here
GPIO27–32	don't use — the QSPI flash bus (EN25QH64A)
GPIO33–37	used by the speaker and BN1/BN2. They're only restricted on chips with octal flash/PSRAM, which this one doesn't have

ADC and Wi-Fi

Only ADC1 (GPIO1–10) works while Wi-Fi is on; ADC2 (GPIO11–20) is shared with the radio. The NTC input is on GPIO1 (ADC1_CH0), so temperature readings and Wi-Fi coexist.

Rev 1 errata

Header P3 silkscreen

The silkscreen next to header P3 reads 3V3, GPIO16, 15, 14, 13, 12, GND. The schematic is correct: the pins are 3V3, GPIO26, 16, 15, 14, 13, GND. GPIO12 is microSD D2 and is not on the header.

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References

• ESP32-S3 datasheet
• ESP32-S3 Technical Reference Manual
• EFZ-ESP32S3 board definition in the EmbeddedFun Zephyr fork
• ESP32-S3-DevKitC in the Zephyr docs — the upstream page this one follows