ESP32 Forum

Dear all,

I am interested in using ESP-WROOM-32D in one of my project where it will be operated as a slave interfaced to an MCU. I was reading through the ESP32 AT Instruction set pdf file provide by espressif. It mentions Default configuration for sending AT Commands is through UART1 which uses GPIO16 - RXD, GPIO17 - TXD, GPIO14 - RTS, GPIO15 - CTS. When i checked the ESP-32 datasheet, the GPIO14, GPIO15 are used as GPIOs and are not specifically RTS/ CTS Pins.

I would like to know if we can use any free gpios on ESP-WROOM-32D Pinout list as UART Pins.

In ESP-WROOM-32D GPIO16- U2RXD, GPIO17 - U2TXD are available for connection and have the same GPIO numbers but U2RTS and U2 CTS are connected to GPIO7 , GPIO 8 respectively. GPIO7, GPIO8 are used to connect to internal flash in ESP-WROOM-32D Module. I am interfacing an external flash with WIFI Module using HSPI Interface. Hence i will not be able to use GPIO14, GPIO15 as RTS/CTS. Can i configure other GPIOs as CTS/RTS.

Thanks in advance

Yes, just beware of input only pins, strapping pins, and internal flash pins.

WiFive wrote:Yes, just beware of input only pins, strapping pins, and internal flash pins.

Thank you for the reply. How can we configure the GPIOs into specific UART Functions. Any link to reference files will be helpful to understand.

Thanks in advance.

https://esp-idf.readthedocs.io/en/lates ... /uart.html
Would suggest you read the docs first, then ask questions.

For AT:
https://github.com/espressif/esp32-at/b ... rt/Kconfig
https://github.com/espressif/esp32-at/b ... ask.c#L195

WiFive wrote:https://esp-idf.readthedocs.io/en/lates ... /uart.html
Would suggest you read the docs first, then ask questions.

For AT:
https://github.com/espressif/esp32-at/b ... rt/Kconfig
https://github.com/espressif/esp32-at/b ... ask.c#L195

Thank you @WiFive. I will go through the links.