Notes On Using Modules; Esp32-Devkitc Development Board - Espressif Systems ESP32 Hardware Design Manuallines

3. HARDWARE DEVELOPMENT

3.6 Notes on Using Modules

• The module uses one single pin as the power supply pin. Users can connect the module to a 3.3V power
supply. The 3.3V power supply works both for the analog circuit and the digital circuit.
• The EN pin is used for enabling the chip. Set the EN pin high for normal working mode. There is no RC
delay circuit on the module. It is recommended that users add an external RC delay circuit to the module.
For details please refer to Section 2.1.2.
• The SMD Module features two working modes: the UART Download mode and the Flash Boot mode. In
the UART Download mode, firmware can be downloaded into the flash memory or the internal memory by
configuring the flash download tool. If the firmware is burnt into the internal memory, it can only run once
and when the module is powered on. When the module is powered down, the internal memory will clear up.
However, if the firmware is burnt and stored into the flash, it will be recalled at any time.
• Lead the GND, RXD, TXD pins out and connect them to a USB-to-TTL tool for firmware download, log-
printing and communication.
By default, the initial firmware has already been downloaded in the flash. If users need to re-download the firmware,
they should follow the steps below:
1. Set the module to UART Download mode by pulling IO0 (pulled up by default) and IO2 (pulled down by
default) low. The chip IOs are pulled down internally by default.
2. Power on the module and check through the serial terminal if the UART Download mode is enabled.
3. Download the firmware to flash, using the
4. After downloading, pull IO0 high or just leave it floating and use the internal weak pull-up to enable the SPI
Boot mode.
5. Power on the module again. The chip will read and execute the firmware during initialization.
Notice:
• During the whole process, users can check the status of the chip with the log printed through UART. If
the firmware cannot be downloaded or executed, users can check if the working mode is normal during
the chip initialization by looking at the log.
• The serial tool cannot be used for both the log-print and flash-download tools simultaneously.

3.7 ESP32-DevKitC Development Board

ESP32-DevKitC is a small-sized ESP32-based development board. The board comes in two versions, either with
ESP-WROOM-32 module or ESP32-WROVER/ESP32-WROVER-I module soldered.
Most of the I/O pins are broken out to the pin headers on both sides for easy interfacing. Developers can connect
these pins to peripherals as needed. Standard headers also make development easy and convenient when using
a breadboard.
The dimensions of the board with ESP-WROOM-32 module are shown in Figure 25.
For more information on this board's layout, schematics, etc, please refer to
Guide.
Espressif Systems
Flash Download Tool.
26 ESP32 Hardware Design Guidelines V2.1
ESP32-DevKitC Getting Started