ESP32 Hardware Design Guidelines
Espressif Systems
December 8, 2016
About This Guide
ESP32 Hardware Design Guidelines provide technical information on the ESP32 series of products, including
ESP32, the ESP-WROOM-32 module, and ESP32-DevKitC - the ESP32 development board.
Related Resources
For additional documentation and resources on ESP32, please visit the website: ESP32 Resources.
Release Notes
Date Version Release notes
2016.12 V1.0 First release
2016.12 V1.1 Updated 4
Disclaimer and Copyright Notice
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 MERCHANTABIL-
ITY, 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 docu-
ment 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 © 2016 Espressif Inc. All rights reserved.
Contents
1 Overview 6
1.1 Basic Protocols 6
1.1.1 Wi-Fi 6
1.1.2 Bluetooth 6
1.2 Application 7
1.3 Function Block Diagram 8
2 Pin Definitions 9
2.1 Pin Layout 9
2.2 Pin Description 9
2.3 Strapping Pins 11
3 Schematics and PCB Layout Design 13
3.1 Schematics 13
3.1.1 Power Supply 14
3.1.1.1 Digital Power Supply 14
3.1.1.2 Analog Power Supply 15
3.1.2 Power-on Sequence and System Reset 15
3.1.2.1 Power-on Sequence 15
3.1.2.2 Reset 15
3.1.3 Flash 16
3.1.4 Crystal Oscillator 16
3.1.4.1 External Clock Source (compulsory) 16
3.1.4.2 RTC (Optional) 17
3.1.5 RF 17
3.1.6 Sensor External Sampling Capacitor 18
3.1.7 External Capacitor 18
3.2 PCB Layout 18
3.2.1 Standalone ESP32 Module 19
3.2.1.1 General Principles of PCB Layout 19
3.2.1.2 Power Supply 19
3.2.1.3 Crystal Oscillator 19
3.2.1.4 RF 20
3.2.2 ESP32 as a Slave Device 21
3.2.3 Typical Layout Problems and Solutions 21
3.2.3.1 Q: The current ripple is not large, but the Tx performance of RF is rather poor. 21
3.2.3.2 Q: The power ripple is small, but RF Tx performance is poor. 22
3.2.3.3 Q: When ESP32 sends data packages, the power value is much higher or lower than the
target power value, and the EVM is relatively poor. 22
3.2.3.4 Q: Tx performance is not bad, but the Rx sensitivity is low. 22
4 Hardware Development 24
4.1 ESP-WROOM-32 Module 24
4.1.1 Overview 24
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