410-377 Datasheet 410-377 | P4-P6

The Pmod ESP32 has the ability to operate in slave mode using the UART interface on

the top row of pins. In slave mode, the device responds to a specific set of AT

commands. More information about the AT command firmware can be found here: ESP

32 AT Source. The device comes pre-configured with the AT command firmware

installed. In slave mode, the SPI peripheral and the GPIOs on the bottom row are

unused.

The Pmod also has the ability to operate in stand alone mode. In stand alone mode, the

user can write custom applications for the ESP 32. Custom applications can interface

with the otherwise unused SPI peripheral and program the two GPIOs in the bottom row

of pins. To send the new application to the ESP32, the user can modify the switches

and use the UART that is connected to the J2 header to both flash and monitor the

device.

Switches

The Pmod ESP32 has two switches. SW1.1 controls whether the top row of the Pmod is

configured as a SPI interface or UART interface. When SW1.1 is set to “on”, the top row

of the Pmod is set as a SPI interface. Alternatively, when SW1.1 is set to “off”, the top

row of the Pmod is set as a UART interface.

SW1.2 controls whether the ESP32 boots into an application stored in memory or, on

power, waits to be flashed with a new application. When SW1.2 is set to “on”, on power,

the ESP 32 will go into a mode where it waits to be flashed with a new application.

When SW1.2 is set to “off”, the ESP 32 will boot and begin to run whatever application it

has stored in its memory.

The behavior of SW1.1 can be driven in software by using the “Select” pin (pin 9).

Driving pin 9 high will cause the Pmod to have UART functionality, regardless of the

value of SW1. Similarly, driving pin 9 low will cause the Pmod to have SPI functionality,

regardless of the value of SW1.1.

Reset Button

After flashing the device with a new application, or when switching between boot modes

specified by SW1.2, it will be necessary to reset the ESP32. A simple press of BTN1 will

cause the ESP32 to reset. Additionally, this can be accomplished in software by utilizing

the Enable pin (pin 8).

On-board LED

The Pmod ESP32 contains an on-board LED that can be directly programmed by the

user. The LED (LD0) is connected to IO12 on the ESP32. When using the AT firmware,

LD0 cannot be directly controlled by the user. However, LD0 can be programmed by

writing custom applications for, and flashing, the ESP32

AT Command (Slave) Mode

The Pmod ESP32 is delivered to users in slave mode. In slave mode, the top row of

pins are mapped to their UART functionality. It is important that switches SW1.1 and

SW1.2 are both in the “off” position when power is applied to the device. Once power

has been applied, the value of SW1.2 is arbitrary. However, SW1.1 must remain in the

“off” position during the duration of operation in slave mode.

In slave mode, commands of a specific format (referred to as AT commands hereafter)

are passed to the Pmod via the UART port on the top row of pins. The UART port on

the Pmod is initially set to function at 115200 baud with 8 data bits, 1 stop bit, and no

parity or hardware flow control. The settings of the UART port can be modified by using

specific AT commands later.

AT commands must always be followed by a carriage return and newline character, in

that order. For example, the AT command “AT” would be typed into the serial terminal

as “AT<CR><LF>”, where CR stands for carriage return and LF stands for line feed or

newline. If the carriage return or line feed are not included at the end of the command,

the Pmod will not respond to the command. The Pmod is initially set to echo back any

UART data it receives to the sender. Upon boot, when in slave mode, the Pmod will

send the word “ready” over the UART port.

A very sparse table of some AT commands is shown below. For the full list of supported

AT commands, please visit the official AT Command Set documentation, which is

provided by Espressif.

Carriage return and line feed bytes are omitted for clarity.

Command Behavior Example Response

AT Verifiesthat

thedeviceis

inATmode

andworking

AT OK

AT+RST Resetsthe

device

AT+RST OK

AT+GMR Checks

versioninfo

AT+GMR <AtVersionInfo>,<SDKversioninfo>,

<compiletime>

Command Behavior Example Response

AT+CWMODE SetstheWiFi

mode

AT+CWMODE=<mode> OK

AT+CWMODE Getsthe

WiFimode

AT+CWMODE? +CWMODE:<mode>

AT+CWJAP Connectsto

aWiFiaccess

point

AT+CWJAP=“some

network”,“some

password”

OKor+CWJAP:<error>

AT+CWJAP Getsinfo

about

connected

WiFiaccess

point

AT+CWJAP? +CWJAP:<ssid>,<bssid>,<channel>,<rssi > 

AT+CWLAP Displays

information

about

available

networks

AT+CWLAP +CWLAP:<ecn>,<ssid>,<rssi>,<mac>,<channel>

Standalone Mode

The Pmod ESP32 features an Xtensa dual-core 32-bit LX5 microprocessor. The Pmod

is delivered to customers with the AT Instruction firmware pre-loaded onto it. However,

the user can write and put custom applications on the Pmod and operate the device

outside of slave mode.

Some reasons for this are:

 Functionality and behavior are not limited by UART baud rate

 The user would like to make use of the SPI peripheral

 The user would like to make use of the programmable GPIOs and LED

 The user wishes to use the SDK provided by Espressif rather than the AT command set

P1-P3 P4-P6 P7-P8

410-377

Mfr. #:

Buy 410-377

Manufacturer:

Digilent

Description:

WiFi Development Tools (802.11) Pmod ESP32: Wireless Communication Module

Lifecycle:

New from this manufacturer.

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