This is the documentation for the latest (main) development branch of Zephyr. If you are looking for the documentation of previous releases, use the drop-down menu on the left and select the desired version.

ESP-WROVER-KIT

Overview

ESP-WROVER-KIT is an ESP32-based development board produced by Espressif.

ESP-WROVER-KIT features the following integrated components:

  • ESP32-WROVER-E module

  • LCD screen

  • MicroSD card slot

Its another distinguishing feature is the embedded FTDI FT2232HL chip - an advanced multi-interface USB bridge. This chip enables to use JTAG for direct debugging of ESP32 through the USB interface without a separate JTAG debugger. ESP-WROVER-KIT makes development convenient, easy, and cost-effective.

Most of the ESP32 I/O pins are broken out to the board’s pin headers for easy access.

Note

ESP32’s GPIO16 and GPIO17 are used as chip select and clock signals for PSRAM. By default, the two GPIOs are not broken out to the board’s pin headers in order to ensure reliable performance.

Functionality Overview

The block diagram below shows the main components of ESP-WROVER-KIT and their interconnections.

ESP-WROVER-KIT

Functional Description

The following two figures and the table below describe the key components, interfaces, and controls of the ESP-WROVER-KIT board.

esp wrover front

Fig. 183 ESP-WROVER-KIT board layout - front

esp wrover back

Fig. 184 ESP-WROVER-KIT board layout - back

The table below provides description in the following manner: - Starting from the first picture’s top right corner and going clockwise - Then moving on to the second picture

Key Component

Description

FT2232

The FT2232 chip serves as a multi-protocol USB-to-serial bridge which can be programmed and controlled via USB to provide communication with ESP32. FT2232 also features USB-to-JTAG interface which is available on channel A of the chip, while USB-to- serial is on channel B. The FT2232 chip enhances user-friendliness in terms of application development and debugging. See ESP-WROVER-KIT V4.1 schematic.

32.768 kHz

External precision 32.768 kHz crystal oscillator serves as a clock with low-power consumption while the chip is in Deep-sleep mode.

0R

Zero-ohm resistor intended as a placeholder for a current shunt, can be desoldered or replaced with a current shunt to facilitate the measurement of ESP32’s current consumption in different modes.

ESP32-WROVER-E module

This ESP32 module features 64-Mbit PSRAM for flexible extended storage and data processing capabilities.

Diagnostic LEDs

Four red LEDs connected to the GPIO pins of FT2232. Intended for future use.

UART

Serial port. The serial TX/RX signals of FT2232 and ESP32 are broken out to the inward and outward sides of JP2 respectively. By default, these pairs of pins are connected with jumpers. To use ESP32’s serial interface, remove the jumpers and connect another external serial device to the respective pins.

SPI

By default, ESP32 uses its SPI interface to access flash and PSRAM memory inside the module. Use these pins to connect ESP32 to another SPI device. In this case, an extra chip select (CS) signal is needed. Please note that the voltage of this interface is 3.3 V.

CTS/RTS

Serial port flow control signals: the pins are not connected to the circuitry by default. To enable them, short the respective pins of JP14 with jumpers.

JTAG

JTAG interface. JTAG signals of FT2232 and ESP32 are broken out to the inward and outward sides of JP2 respectively. By default, these pairs of pins are disconnected. To enable JTAG, short the respective pins with jumpers as shown in Section Setup Options

USB Port

USB interface. Power supply for the board as well as the communication interface between a computer and the board.

EN Button

Reset button.

BOOT Button

Download button. Holding down Boot and then pressing EN initiates Firmware Download mode for downloading firmware through the

Power Switch

Power On/Off Switch. Toggling toward the Boot button powers the board on, toggling away from Boot powers the board off.

Power Selector

Power supply selector interface. The board can be powered either via USB or via the 5V Input interface. Select the power source with a jumper. For more details, see Section Setup Options, jumper header JP7.

5V input

5V power supply interface for a standard coaxial power connector, 5.5 x 2.1 mm, center positive. This interface can be more convenient when the board is operating autonomously (not connected to a computer).

5V Power On LED

This red LED turns on when power is supplied to the board, either from USB or 5V Input.

LDO

NCP1117(1A). 5V-to-3.3V LDO. NCP1117 can provide a maximum current of 1A. The LDO on the board has a fixed output voltage. Although, the user can install an LDO with adjustable output voltage. For details, please refer to ESP-WROVER-KIT V4.1 schematic.

Camera Connector

Camera interface, a standard OV7670 camera module.

RGB LED

Red, green and blue (RGB) light emitting diodes (LEDs), can be controlled by pulse width modulation (PWM).

I/O Connector

All the pins on the ESP32 module are broken out to pin headers. You can program ESP32 to enable multiple functions, such as PWM, ADC, DAC, I2C, I2S, SPI, etc.

MicroSD Card Slot

Useful for developing applications that access MicroSD card for data storage and retrieval.

LCD

Support for mounting and interfacing a 3.2” SPI (standard 4-wire Serial Peripheral Interface) LCD, as shown on figure ESP-WROVER-KIT board layout - back

Setup Options

There are three jumper blocks available to set up the board functionality. The most frequently required options are listed in the table below.

Header | Jumper Setting | Description of Functionality

JP7

jmpextpwr

Power ESP-WROVER-KIT via an external power supply

JP7

jmpusbpwr

Power ESP-WROVER-KIT via USB

JP2

jmpjtag

Enable JTAG functionality

JP2

jmpuart

Enable UART communication

JP14

jmpctrl

Enable RTS/CTS flow control for serial communication

Allocation of ESP32 Pins

Some pins / terminals of ESP32 are allocated for use with the onboard or external hardware. If that hardware is not used, e.g., nothing is plugged into the Camera (JP4) header, then these GPIOs can be used for other purposes.

Some of the pins, such as GPIO0 or GPIO2, have multiple functions and some of them are shared among onboard and external peripheral devices. Certain combinations of peripherals cannot work together. For example, it is not possible to do JTAG debugging of an application that is using SD card, because several pins are shared by JTAG and the SD card slot.

In other cases, peripherals can coexist under certain conditions. This is applicable to, for example, LCD screen and SD card that share only a single pin GPIO21. This pin is used to provide D/C (Data / Control) signal for the LCD as well as the Card Detect signal read from the SD card slot. If the card detect functionality is not essential, then it may be disabled by removing R167, so both LCD and SD may operate together.

For more details on which pins are shared among which peripherals, please refer to the table in the next section.

Main I/O Connector / JP1

The JP1 connector consists of 14x2 male pins whose functions are shown in the middle two “I/O” columns of the table below. The two “Shared With” columns on both sides describe where else on the board a certain GPIO is used.

Shared With

I/O

I/O

Shared With

n/a

3.3V

GND

n/a

NC/XTAL

IO32

IO33

NC/XTAL

JTAG, MicroSD

IO12

IO13

JTAG, MicroSD

JTAG, MicroSD

IO14

IO27

Camera

Camera

IO26

IO25

Camera, LCD

Camera

IO35

IO34

Camera

Camera

IO39

IO36

Camera

JTAG

EN

IO23

Camera, LCD

Camera, LCD

IO22

IO21

Camera, LCD, MicroSD

Camera, LCD

IO19

IO18

Camera, LCD

Camera, LCD

IO5

IO17

PSRAM

PSRAM

IO16

IO4

LED, Camera, MicroSD

Camera, LED, Boot

IO0

IO2

LED, MicroSD

JTAG, MicroSD

IO15

5V

Legend:

  • NC/XTAL - 32.768 kHz Oscillator

  • JTAG - JTAG / JP2

  • Boot - Boot button / SW2

  • Camera - Camera / JP4

  • LED - RGB LED

  • MicroSD - MicroSD Card / J4

  • LCD - LCD / U5

  • PSRAM - ESP32-WROVER-E’s PSRAM

32.768 kHz Oscillator

.

ESP32 Pin

1

GPIO32

2

GPIO33

Note

Since GPIO32 and GPIO33 are connected to the oscillator by default, they are not connected to the JP1 I/O connector to maintain signal integrity. This allocation may be changed from the oscillator to JP1 by desoldering the zero-ohm resistors from positions R11 / R23 and re- soldering them to positions R12 / R24.

SPI Flash / JP2

.

ESP32 Pin

1

CLK / GPIO6

2

SD0 / GPIO7

3

SD1 / GPIO8

4

SD2 / GPIO9

5

SD3 / GPIO10

6

CDM / GPIO11

Important

The module’s flash bus is connected to the jumper block JP2 through zero-ohm resistors R140 ~ R145. If the flash memory needs to operate at the frequency of 80 MHz, for reasons such as improving the integrity of bus signals, you can desolder these resistors to disconnect the module’s flash bus from the pin header JP2.

JTAG / JP2

.

ESP32 Pin

JTAG Signal

1

EN

TRST_N

2

MTMS / GPIO14

TMS

3

MTDO / GPIO15

TDO

4

MTDI / GPIO12

TDI

5

MTCK / GPIO13

TCK

Camera / JP4

.

ESP32 Pin

Camera Signal

1

n/a

3.3V

2

n/a

Ground

3

GPIO27

SIO_C / SCCB Clock

4

GPIO26

SIO_D / SCCB Data

5

GPIO25

VSYNC / Vertical Sync

6

GPIO23

HREF / Horizontal Reference

7

GPIO22

PCLK / Pixel Clock

8

GPIO21

XCLK / System Clock

9

GPIO35

D7 / Pixel Data Bit 7

10

GPIO34

D6 / Pixel Data Bit 6

11

GPIO39

D5 / Pixel Data Bit 5

12

GPIO36

D4 / Pixel Data Bit 4

13

GPIO19

D3 / Pixel Data Bit 3

14

GPIO18

D2 / Pixel Data Bit 2

15

GPIO5

D1 / Pixel Data Bit 1

16

GPIO4

D0 / Pixel Data Bit 0

17

GPIO0

RESET / Camera Reset

18

n/a

PWDN / Camera Power Down

  • Signals D0 .. D7 denote camera data bus

RGB LED

.

ESP32 Pin

RGB LED

1

GPIO0

Red

2

GPIO2

Green

3

GPIO4

Blue

MicroSD Card

.

ESP32 Pin

MicroSD Signal

1

MTDI / GPIO12

DATA2

2

MTCK / GPIO13

CD / DATA3

3

MTDO / GPIO15

CMD

4

MTMS / GPIO14

CLK

5

GPIO2

DATA0

6

GPIO4

DATA1

7

GPIO21

Card Detect

LCD / U5

.

ESP32 Pin

LCD Signal

1

GPIO18

RESET

2

GPIO19

SCL

3

GPIO21

D/C

4

GPIO22

CS

5

GPIO23

SDA

6

GPIO25

SDO

7

GPIO5

Backlight

Start Application Development

Before powering up your ESP-WROVER-KIT, please make sure that the board is in good condition with no obvious signs of damage.

Initial Setup

Please set only the following jumpers shown in the pictures below:

  • Select USB as the power source using the jumper block JP7.

  • Enable UART communication using the jumper block JP2.

Power up from USB port

Enable UART communication

jmpusbpwr

jmpuart

Do not install any other jumpers.

Turn the Power Switch to ON, the 5V Power On LED should light up.

System requirements

Build Environment Setup

Some variables must be exported into the environment prior to building this port. Find more information at Environment Variables on how to keep this settings saved in you environment.

Note

In case of manual toolchain installation, set ESPRESSIF_TOOLCHAIN_PATH accordingly. Otherwise, set toolchain path as below. If necessary.

On Linux and macOS:

export ZEPHYR_TOOLCHAIN_VARIANT="espressif"
export ESPRESSIF_TOOLCHAIN_PATH="${HOME}/.espressif/tools/zephyr"

On Windows:

# on CMD:
set ESPRESSIF_TOOLCHAIN_PATH=%USERPROFILE%\.espressif\tools\zephyr
set ZEPHYR_TOOLCHAIN_VARIANT=espressif

# on PowerShell
$env:ESPRESSIF_TOOLCHAIN_PATH="$env:USERPROFILE\.espressif\tools\zephyr"
$env:ZEPHYR_TOOLCHAIN_VARIANT="espressif"

Finally, retrieve required submodules to build this port. This might take a while for the first time:

west espressif update

Note

It is recommended running the command above after west update so that submodules also get updated.

Flashing

The usual flash target will work with the esp_wrover_kit board configuration. Here is an example for the Hello World application.

# From the root of the zephyr repository
west build -b esp_wrover_kit samples/hello_world
west flash

Refer to Building an Application and Run an Application for more details.

It’s impossible to determine which serial port the ESP-WROVER-KIT board is connected to, as it uses a generic RS232-USB converter. The default of /dev/ttyUSB1 is provided as that’s often the assigned name on a Linux machine without any other such converters.

The baud rate of 921600bps is recommended. If experiencing issues when flashing, try halving the value a few times (460800, 230400, 115200, etc).

All flashing options are now handled by the West (Zephyr’s meta-tool) tool, including flashing with custom options such as a different serial port. The west tool supports specific options for the ESP32-S2 board, as listed here:

--esp-idf-path ESP_IDF_PATH

path to ESP-IDF

--esp-device ESP_DEVICE

serial port to flash, default $ESPTOOL_PORT if defined. If not, esptool will loop over available serial ports until it finds ESP32 device to flash.

--esp-baud-rate ESP_BAUD_RATE

serial baud rate, default 921600

--esp-flash-size ESP_FLASH_SIZE

flash size, default “detect”

--esp-flash-freq ESP_FLASH_FREQ

flash frequency, default “40m”

--esp-flash-mode ESP_FLASH_MODE

flash mode, default “dio”

--esp-tool ESP_TOOL

if given, complete path to espidf. default is to search for it in [ESP_IDF_PATH]/components/esptool_py/ esptool/esptool.py

--esp-flash-bootloader ESP_FLASH_BOOTLOADER

Bootloader image to flash

--esp-flash-partition_table ESP_FLASH_PARTITION_TABLE

Partition table to flash

For example, to flash to /dev/ttyUSB2, use the following command after having build the application in the build directory:

west flash -d build/ --skip-rebuild --esp-device /dev/ttyUSB2