ESP32 Forum

Support required to Flash in ESP32-S2-mini for custom board (Renesas) with customizable DFU firmware

What is your question? Have you looked at https://github.com/espressif/esp-serial-flasher already?

https://docs.espressif.com/projects/esp ... s/dfu.html
Note that the bootloader also supports USB-CDC, and the Arduino IDE (using esptool) can deliver a firmware over CDC.

Can you share the ESP32-S2 mini serial programing protocol document for understating the code flow? Please share the document.

ESP_Sprite wrote: ↑

Mon Nov 20, 2023 6:21 am

What is your question? Have you looked at https://github.com/espressif/esp-serial-flasher already?

I have referred the given example code of stm32_example, In that UART transmission is making conflict with SPI and incomplete code, even in SPI transmission final transmit function is missing can't able to track.

1. SPI is used for Flash erasing, in loader SPI parameter inside-> send command function available (That particular function which available in both SPI and UART protocol files, which I should consider?
2. In readme file, SPI is mentioned as "SPI (only for RAM download, experimental)" but in flash erasing is handled by SPI why not UART please make clarity on this?
3. As I can able to find UART is configured max of the limit as "HIGHER_BAUDRATE 230400" but UART standard will support max of 115200, When I configured as UART standard max limit of 115200 does it work as normal system?
4. Need UART protocol frame->Data format, How its processing the request and response?

Please share me the UART based DFU working reference code for any controller?
Thanking in advance..

I think you're not understanding how ESP32 chips work. ESP chips or modules don't have their own flash on-silicon; they must be paired with some kind of SPI flash that contains the program they run. That flash can be either in the chip package or in the module or added externally. That is what 'SPI' refers to. This SPI flash gets programmed by the ESP32 by putting the ESP32 into download mode and sending it commands via the UART; the UART connection is what the library I linked to implements. As the UART commands describe what the ESP32 needs to do to the SPI flash, you will see 'SPI' in the source code, but that does not refer to the connection between your microcontroller and the ESP32; that still is UART.

Hope that clears things up.

ESP_Sprite wrote: ↑

Wed Nov 22, 2023 7:45 am

I think you're not understanding how ESP32 chips work. ESP chips or modules don't have their own flash on-silicon; they must be paired with some kind of SPI flash that contains the program they run. That flash can be either in the chip package or in the module or added externally. That is what 'SPI' refers to. This SPI flash gets programmed by the ESP32 by putting the ESP32 into download mode and sending it commands via the UART; the UART connection is what the library I linked to implements. As the UART commands describe what the ESP32 needs to do to the SPI flash, you will see 'SPI' in the source code, but that does not refer to the connection between your microcontroller and the ESP32; that still is UART.

Hope that clears things up.

Thanks for sharing the information,
Just I want a confirmation, against on your shared overview information? please refer the below attachment for my understanding!
And could you please share me the UART protocol document for BOOTLOADER RE-FLASHING.

It would be easier for us to help you if you explained what you would like to achieve, instead of asking for pieces of technical information. Your diagram above is correct. Here is the documentation on the serial bootloader from esptool.
https://docs.espressif.com/projects/esp ... tocol.html

lbernstone wrote: ↑

Wed Nov 22, 2023 3:44 pm

It would be easier for us to help you if you explained what you would like to achieve, instead of asking for pieces of technical information. Your diagram above is correct. Here is the documentation on the serial bootloader from esptool.
https://docs.espressif.com/projects/esp ... tocol.html

thank you for sharing this

Note that there are two bootloaders: the first stage lives in ROM and cannot be flashed ever, the 2nd stage lives in the SPI flash and you generally flash that automatically along with your application.