ESP32-WROOM-32D & ESP32-WROOM-32U Datasheet

About This Document

This document provides the specifications for the ESP32-WROOM-32D and ESP32-WROOM-32U modules.

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Information in this document, including URL references, is subject to change without notice. THIS DOCUMENT IS PROVIDED AS IS WITH NO WARRANTIES WHATSOEVER, INCLUDING ANY WARRANTY OF MERCHANTABILITY, NON-INFRINGEMENT, FITNESS FOR ANY PARTICULAR PURPOSE, OR ANY WARRANTY OTHERWISE ARISING OUT OF ANY PROPOSAL, SPECIFICATION OR SAMPLE. All liability, including liability for infringement of any proprietary rights, relating to use of information in this document is disclaimed. No licenses express or implied, by estoppel or otherwise, to any intellectual property rights are granted herein. The Wi-Fi Alliance Member logo is a trademark of the Wi-Fi Alliance. The Bluetooth logo is a registered trademark of Bluetooth SIG. All trade names, trademarks and registered trademarks mentioned in this document are property of their respective owners, and are hereby acknowledged. Copyright © 2018 Espressif Inc. All rights reserved.

Overview

ESP32-WROOM-32D and ESP32-WROOM-32U are powerful, generic Wi-Fi+BT+BLE MCU modules that target a wide variety of applications, ranging from low-power sensor networks to the most demanding tasks, such as voice encoding, music streaming and MP3 decoding. ESP32-WROOM-32U is different from ESP32-WROOM-32D in that ESP32-WROOM-32U integrates a U.FL connector. For detailed information of the U.FL connector please see Chapter 10.

At the core of the two modules are the ESP32-D0WD chip*. The chip embedded is designed to be scalable and adaptive. There are two CPU cores that can be individually controlled, and the CPU clock frequency is adjustable from 80 MHz to 240 MHz. The user may also power off the CPU and make use of the low-power co-processor to constantly monitor the peripherals for changes or crossing of thresholds. ESP32 integrates a rich set of peripherals, ranging from capacitive touch sensors, Hall sensors, SD card interface, Ethernet, high-speed SPI, UART, I2S and I2C.

Note: * For details on the part number of the ESP32 series, please refer to the document ESP32 Datasheet.

The integration of Bluetooth, Bluetooth LE and Wi-Fi ensures that a wide range of applications can be targeted, and that the module is future proof: using Wi-Fi allows a large physical range and direct connection to the internet through a Wi-Fi router, while using Bluetooth allows the user to conveniently connect to the phone or broadcast low energy beacons for its detection. The sleep current of the ESP32 chip is less than 5 µA, making it suitable for battery powered and wearable electronics applications. ESP32 supports a data rate of up to 150 Mbps, and 20.5 dBm output power at the antenna to ensure the widest physical range. As such the chip does offer industry-leading specifications and the best performance for electronic integration, range, power consumption, and connectivity.

The operating system chosen for ESP32 is freeRTOS with LwIP; TLS 1.2 with hardware acceleration is built in as well. Secure (encrypted) over the air (OTA) upgrade is also supported, so that developers can continually upgrade their products even after their release.

Table 2 provides the specifications of ESP32-WROOM-32D and ESP32-WROOM-32U.

Pin Definitions

Pin Layout

Textual description of Figure 1: A top-down view of the ESP32-WROOM-32D module showing the arrangement of 38 pins around its perimeter, with a central keepout zone indicated. Pin numbers and basic labels are shown.

Note: The pin layout of ESP32-WROOM-32U is the same as that of ESP32-WROOM-32D, except that ESP32-WROOM-32U has no keepout zone.

Pin Description

The ESP32-WROOM-32D and ESP32-WROOM-32U have 38 pins. See pin definitions in Table 3.

Important: * Pins SCK/CLK, SDO/SD0, SDI/SD1, SHD/SD2, SWP/SD3 and SCS/CMD, namely, GPIO6 to GPIO11 are connected to the integrated SPI flash integrated on the module and are not recommended for other uses.

Strapping Pins

ESP32 has five strapping pins, which can be seen in Chapter 6 Schematics:

• MTDI
• GPIO0
• GPIO2
• MTDO
• GPIO5

Software can read the values of these five bits from register "GPIO_STRAPPING". During the chip's system reset (power-on-reset, RTC watchdog reset and brownout reset), the latches of the strapping pins sample the voltage level as strapping bits of "0" or "1", and hold these bits until the chip is powered down or shut down. The strapping bits configure the device's boot mode, the operating voltage of VDD_SDIO and other initial system settings.

Each strapping pin is connected to its internal pull-up/pull-down during the chip reset. Consequently, if a strapping pin is unconnected or the connected external circuit is high-impedance, the internal weak pull-up/pull-down will determine the default input level of the strapping pins.

To change the strapping bit values, users can apply the external pull-down/pull-up resistances, or use the host MCU's GPIOs to control the voltage level of these pins when powering on ESP32.

After reset, the strapping pins work as normal-function pins.

Refer to Table 4 for a detailed boot-mode configuration by strapping pins.

Note: • Firmware can configure register bits to change the settings of "Voltage of Internal LDO (VDD_SDIO)" and "Timing of SDIO Slave" after booting. • Both ESP32-WROOM-32D and ESP32-WROOM-32U integrate a 3.3V SPI flash, so the pin MTDI cannot be set to 1 when the modules are powered up.

Functional Description

CPU and Internal Memory

ESP32-D0WD contains a dual-core Xtensa® 32-bit LX6 MCU. The internal memory includes:

• 448 kB of ROM for booting and core functions.
• 520 kB of on-chip SRAM for data and instructions.
• 8 kB of SRAM in RTC, which is called RTC FAST Memory and can be used for data storage; it is accessed by the main CPU during RTC Boot from the Deep-sleep mode.
• 8 kB of SRAM in RTC, which is called RTC SLOW Memory and can be accessed by the co-processor during the Deep-sleep mode.
• 1 kbit of eFuse: 256 bits are used for the system (MAC address and chip configuration) and the remaining 768 bits are reserved for customer applications, including flash-encryption and chip-ID.

External Flash and SRAM

ESP32 supports multiple external QSPI flash and SRAM chips. More details can be found in Chapter SPI in the ESP32 Technical Reference Manual. ESP32 also supports hardware encryption/decryption based on AES to protect developers' programs and data in flash.

ESP32 can access the external QSPI flash and SRAM through high-speed caches.

• Up to 16 MB of external flash can be mapped into CPU instruction memory space and read-only memory space simultaneously.
• When external flash is mapped into CPU instruction memory space, up to 11 MB+248 KB can be mapped at a time. Note that if more than 3 MB+248 KB are mapped, cache performance will be reduced due to speculative reads by the CPU.
• When external flash is mapped into read-only data memory space, up to 4 MB can be mapped at a time. 8-bit, 16-bit and 32-bit reads are supported.
• External SRAM can be mapped into CPU data memory space. SRAM up to 8 MB is supported and up to 4 MB can be mapped at a time. 8-bit, 16-bit and 32-bit reads and writes are supported.

Both ESP32-WROOM-32D and ESP32-WROOM-32U integrate a 4 MB of external SPI flash. The 4-MB SPI flash can be memory-mapped onto the CPU code space, supporting 8, 16 and 32-bit access. Code execution is supported. The integrated SPI flash is connected to GPIO6, GPIO7, GPIO8, GPIO9, GPIO10 and GPIO11. These six pins cannot be used as regular GPIOs.

Crystal Oscillators

The module uses a 40-MHz crystal oscillator.

RTC and Low-Power Management

With the use of advanced power-management technologies, ESP32 can switch between different power modes.

• Power modes
  • Active mode: The chip radio is powered on. The chip can receive, transmit, or listen.
  • Modem-sleep mode: The CPU is operational and the clock is configurable. The Wi-Fi/Bluetooth base-band and radio are disabled.
  • Light-sleep mode: The CPU is paused. The RTC memory and RTC peripherals, as well as the ULP co-processor are running. Any wake-up events (MAC, host, RTC timer, or external interrupts) will wake up the chip.
  • Deep-sleep mode: Only RTC memory and RTC peripherals are powered on. Wi-Fi and Bluetooth connection data are stored in the RTC memory. The ULP co-processor is functional.
  • Hibernation mode: The internal 8-MHz oscillator and ULP co-processor are disabled. The RTC recovery memory is powered down. Only one RTC timer on the slow clock and certain RTC GPIOs are active. The RTC timer or the RTC GPIOs can wake up the chip from the Hibernation mode.

The power consumption varies with different power modes and work statuses of functional modules. Please see Table 5 for details.

Note: • When Wi-Fi is enabled, the chip switches between Active and Modem-sleep mode. Therefore, power consumption changes accordingly. • In Modem-sleep mode, the CPU frequency changes automatically. The frequency depends on the CPU load and the peripherals used. • During Deep-sleep, when the ULP co-processor is powered on, peripherals such as GPIO and I2C are able to operate. • When the system works in the ULP sensor-monitored pattern, the ULP co-processor works with the ULP sensor periodically; ADC works with a duty cycle of 1%, so the power consumption is 100 µA.

Peripherals and Sensors

Please refer to Section Peripherals and Sensors in ESP32 Datasheet.

Note: External connections can be made to any GPIO except for GPIOs in the range 6-11. These six GPIOs are connected to the module's integrated SPI flash. For details, please see Section 6 Schematics.

Electrical Characteristics

Absolute Maximum Ratings

Stresses beyond the absolute maximum ratings listed in the table below may cause permanent damage to the device. These are stress ratings only, and do not refer to the functional operation of the device.

Recommended Operating Conditions

DC Characteristics (3.3V, 25°C)

1. VDD is the I/O voltage for a particular power domain of pins. More details can be found in Appendix IO_MUX of ESP32 Datasheet.

Wi-Fi Radio

*For the modules that use IPEX antennas, the output impedance is 50Ω. For other modules without IPEX antennas, users do not need to concern about the output impedance.

BLE Radio

Receiver

Transmitter

Reflow Profile

Textual description of Figure 2: A graph illustrating the reflow soldering profile. The X-axis represents time in seconds, and the Y-axis represents temperature in degrees Celsius. It shows distinct zones: Ramp-up zone (1-3°C/s), Preheating zone (150-200°C, 60-120s), Reflow zone (>217°C, 60-90s, Peak Temp. 235-250°C), and Cooling zone (-1 to -5°C/s). Key parameters like soldering time (>30s) and recommended peak temperature (<245°C) are indicated.

Schematics

Textual description of Figure 3: A schematic diagram illustrating the internal circuitry and connections for the ESP32-WROOM-32D module, showing the ESP32-D0WD chip, associated passive components like capacitors and resistors, and pin connections.

Textual description of Figure 4: A schematic diagram illustrating the internal circuitry and connections for the ESP32-WROOM-32U module, similar to Figure 3 but adapted for the U.FL connector variant.

Textual description of Figure 5: A peripheral schematic diagram showing the ESP32-WROOM-32D and ESP32-WROOM-32U modules connected to external components for UART download and JTAG debugging, indicating necessary connections like EN, TXD0, RXD0, and strapping pins like MTDI.

Physical Dimensions

Textual description of Figure 6: Technical drawings detailing the physical dimensions of the ESP32-WROOM-32D module. It includes front, side, and back views with precise measurements for length, width, thickness, and key features like the antenna area, presented in millimeters.

Textual description of Figure 7: Technical drawings detailing the physical dimensions of the ESP32-WROOM-32U module. It includes front, side, and back views with precise measurements for length, width, thickness, and key features, presented in millimeters.

Recommended PCB Land Pattern

Textual description of Figure 8: A recommended PCB land pattern for the ESP32-WROOM-32D module. It shows the footprint layout with pad dimensions and placement guidance for surface mounting, measured in millimeters.

Textual description of Figure 9: A recommended PCB land pattern for the ESP32-WROOM-32U module. It shows the footprint layout with pad dimensions and placement guidance for surface mounting, measured in millimeters.

U.FL Connector Dimensions

Textual description of Figure 10: Technical drawings detailing the dimensions of the U.FL connector used with the ESP32-WROOM-32U module. It includes various views and close-ups with precise measurements in millimeters.

Learning Resources

Must-Read Documents

• ESP32 Datasheet: This document provides an introduction to the specifications of the ESP32 hardware, including overview, pin definitions, functional description, peripheral interface, electrical characteristics, etc.
• ESP-IDF Programming Guide: It hosts extensive documentation for ESP-IDF ranging from hardware guides to API reference.
• ESP32 Technical Reference Manual: The manual provides detailed information on how to use the ESP32 memory and peripherals.
• ESP32 Hardware Resources: The zip files include the schematics, PCB layout, Gerber and BOM list of ESP32 modules and development boards.
• ESP32 Hardware Design Guidelines: The guidelines outline recommended design practices when developing standalone or add-on systems based on the ESP32 series of products, including the ESP32 chip, the ESP32 modules and development boards.
• ESP32 AT Instruction Set and Examples: This document introduces the ESP32 AT commands, explains how to use them, and provides examples of several common AT commands.
• Espressif Products Ordering Information

Must-Have Resources

• ESP32 BBS: This is an Engineer-to-Engineer (E2E) Community for ESP32 where you can post questions, share knowledge, explore ideas, and help solve problems with fellow engineers.
• ESP32 GitHub: ESP32 development projects are freely distributed under Espressif's MIT license on GitHub. It is established to help developers get started with ESP32 and foster innovation and the growth of general knowledge about the hardware and software surrounding ESP32 devices.
• ESP32 Tools: This is a webpage where users can download ESP32 Flash Download Tools and the zip file "ESP32 Certification and Test".
• ESP-IDF: This webpage links users to the official IoT development framework for ESP32.
• ESP32 Resources: This webpage provides the links to all available ESP32 documents, SDK and tools.

Revision History