flashing firmware to raw ESP32-C3-wroom-02-N4 in a custom PCB

[Cristian_bcc]

Hello everyone
I'm developing an IoT solution that is just a prototype for the moment. Until now i've used esp32-c3 wroom development boards, to realize the prototypes, and i've flashed the firmware through onBoard USB-Uart converter using Arduino IDE.
I would pass to the next step and realize a first round of industrial PCBs realization, by means of web service to make a series of my own custom circuits on a PCB.
What i'm interesting to know is, how to flash firmware on these circuits. In particular:
-I suppose that in the development board esp32 circuit there is a bootloader to allow flashing by Arduino IDE and Serial port, is this true?
-In this case, raw esp32 components have a native bootloader or i have to flash it, eventually, how can i flash the bootloader?
-Without the bootloader how can i flash my desired firmware from arduino IDE to the ESP32 on the custom PCB?
-I need usb2uart converter or there is an alternative way?

Please help me to solve my doubt, thank you in advance.
Cristian

[ESP_Sprite]

The bootloader that is responsible for flashing the chips is baked into ROM in the factory in case of ESP32 chips: you do not have to (and in fact cannot) flash it; it works out of the box. On the C3, you can either use the serial port or the built-in USB to initially flash the chip. Note that if you use the latter, you might want to have a way to pull IO9 low for the initial flash.

[Cristian_bcc]

Thank you so much, very kind
If i use usb-to-serial converter is there any routine to be executed (pulling up or down any pins or something similar)?

Moreover, if i'm working on arduino project, is there a way to make a DFU image to be flashed with built-in USB or to directly flash from arduino IDE in DFU mode or maybe is it necessary working on IDF ?

[ESP_Sprite]

Thank you so much, very kind
If i use usb-to-serial converter is there any routine to be executed (pulling up or down any pins or something similar)?

As I said, you probably want to be able to pull GPIO9 low for the initial flash.

Moreover, if i'm working on arduino project, is there a way to make a DFU image to be flashed with built-in USB or to directly flash from arduino IDE in DFU mode or maybe is it necessary working on IDF ?

No. The C3 does not have USB-OTG, and the USB-serial-JTAG module is not capable of DFU.