Digilent Pmod ESP32 Referenzhandbuch - Seite 4

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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).

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