Power supply and UART Connection for ESP-WROOM-32D

[FCT_IOT]

Dear all,

I would like to interface the ESP-WROOM-32D module with host mcu. I need following clarifications related to afore mentioned ESP Module.

1. AT instruction set document mentions that GPIO16, GPIO17, GPIO14, GPIO15 (UART 2 pins in ESP-WROOM-32D) are used by default for AT Command transfer. The GPIO14, GPIO15 are used to connect to internal SPI Flash. I would like to know if i can disable MTDO (which will disable UART0 to be used for debug purpose) and use UART0 for AT Command transfer, firmware Download through uart. I am interested in using Flow control hence i would like to know the feasibility of using UART0.

2. If i power the ESP-WROOM-32D using a 3V power supply, Will it have any effect on the internal flash module interface and what will be the VDD_SDIO pin voltage. The datasheet of ESP32 mentions that vdd_sdio output voltage is either 1.8 V or the VDD3P3_RTC voltage (Which will be the same as supply voltage (3V)).

3. The time taken by the WIFI Module to wakeup from light sleep / modem sleep / deep sleep modes.

Thanks in advance.

[WiFive]

mtdo strapping pin only disables early rom boot logs, you have to build at firmware configured for uart0 and reconfigure logging

Vdd_sdio voltage is set by mtdi strapping pin or efuse

[FCT_IOT]

mtdo strapping pin only disables early rom boot logs, you have to build at firmware configured for uart0 and reconfigure logging

Vdd_sdio voltage is set by mtdi strapping pin or efuse

I would like to know if there is any impact on the VDD_SDIO voltage, if i provide 3V to ESP-WROOM-32D Module. Since internal LDO generates the voltage, will VDD_SDIO also be 3V or 3.3 V....?

This post mentions UART0 is configured by default method to load images into flash. Can we use the same UART0 interface to send and receive the AT Commands...?
http://bbs.esp32.com/viewtopic.php?f=13&t=388


Thanks in advance.

[WiFive]

Sdio voltage will be 1.8v if internal regulator is enabled, otherwise it will be equal to your supply voltage. Ldo cannot boost voltage.

Uart0 is used for firmware update in download boot mode. For normal boot mode you can use it for at commands if you build the firmware with that configuration. https://github.com/espressif/esp32-at

[FCT_IOT]

Sdio voltage will be 1.8v if internal regulator is enabled, otherwise it will be equal to your supply voltage. Ldo cannot boost voltage.

Uart0 is used for firmware update in download boot mode. For normal boot mode you can use it for at commands if you build the firmware with that configuration. https://github.com/espressif/esp32-at

Thank you @WiFive for the Clarification.

[FCT_IOT]

Sdio voltage will be 1.8v if internal regulator is enabled, otherwise it will be equal to your supply voltage. Ldo cannot boost voltage.

Uart0 is used for firmware update in download boot mode. For normal boot mode you can use it for at commands if you build the firmware with that configuration. https://github.com/espressif/esp32-at

Dear @WiFive,

I am a bit confused about the usage of UART0 Interface, need a bit of clarification. Uart 0 interface serves the purpose as a debug port and as mentioned in few posts in this forum it is configured as a default port for firmware download.

Does UART0 TXD Pin only print logs during the booting process and post bootup it will work as a normal UART Interface which can be used for firmware download.

Although the posts in this forum mentions about using UART0 as default port to load images into flash, The datasheet/technical reference manual has no mention of this.

Thanks in advance

[WiFive]

https://github.com/espressif/esp-idf/bl ... #L394-L405

https://github.com/espressif/esptool/wi ... -Selection

[FCT_IOT]

https://github.com/espressif/esp-idf/bl ... #L394-L405

https://github.com/espressif/esptool/wi ... -Selection

Dear @WiFive,

In the factory image loaded in ESPWROOM-32D, will UART0 be configured for firmware download or as a debug port. I understand that we can configure the UART0 port based on the links that were shared. Will it not be a issue during first time programming of the flash if UART 0 is configured as a debug port only.

I want to control ESP-WROOM-32D using an External MCU. Can I use UART0 to interface with the MCU and also to program the ESP32 by taking the UART0 lines to an external connector or

Do i need to use a dedicated uart interface (uart0 - connected to PC through external connector) for programming the flash and connect the esp-wroom-32d with MCU using UART1 for communication.

I have attached block diagram of two scenarios i am thinking of for firmware update. I have not indicated the CTS/RTS Connection but i will be using them and also i will take care of pin strapping of MTDO, GPIO2. I would like to know if there will be any issue, when i operate as per the second option in passthrough mode.

Thanks in advance.

[WiFive]

It is fine as long as you can boot the esp32 in the bootloader mode you want using en and gpio 0/2. The modes are totally separate so they can't interfere.

[FCT_IOT]

It is fine as long as you can boot the esp32 in the bootloader mode you want using en and gpio 0/2. The modes are totally separate so they can't interfere.

Dear @WiFive,

I would like to know if it is okay to use UART-0 for interfacing with MCU and also connecting it to PC for firmware download through USB-UART Converter as shown in Option-1 block diagram.

In my design I am using HSPI Interface to connect to External flash. HSPICS0 Signal and MTDO are on the same pin. If I have to disable the flash boot log on the UART-0 Terminal how can i do it.

By default is UART-0 Terminal configured in the factory image for UART Download...?