ESP32 Forum

Hello!

Designing a custom Wroom32 board .
Looking for Auto Programming Circuit without the need of USB to UART converter.
one of the available Schematic shows DTR ans RTS connected to Auto programming Circuit from an USB- UART converter.
How to implement the same from the Wroom32 Chip directly so that Only OTA is satisfied?

Is the USB-UART converter and Auto Programming Circuit required for only OTA application???

Thank You

Hi Sathiyan,

Sorry, but I'm not sure I understand the question.

For OTA applications (where the ESP32 loads firmware via WiFi or Bluetooth), no external connections are required. All of the SPI flash writes are performed by your firmware running on the device. This is entirely done with the ESP32 firmware.

However, if the device is to be initially programmed via serial UART, the correct bootstrapping pins need to be set in order to put the chip into a serial programming mode. You can read these in the ESP32 Datasheet or there is a short summary on the esptool wiki.

There are many ways to set these pins, including buttons or jumpers or the DTR/RTS connections you mention. Connecting DTR & RTS allows esptool.py to automatically reset the ESP32 into bootloader mode via the serial port.

There are other ways to perform initial programming in a factory setting, for example programming the SPI flash pins of the WROOM module directly. These approaches are not usually suitable for prototyping or development, though.

Does this answer your question? If you can explain some more about what you're trying to achieve this may help.

You may also want to obtain an existing development board and run through the ESP-IDF Getting Started guide to flash via serial, then maybe experiment with the basic OTA example in ESP-IDF. This will help familiarise yourself with these concepts.