ESP32 Forum

Hello everyone,

I m doing an iot product in which i m using esp32d0wdq6 controller. i have designed my own board and soldered an new bare ic, spi flash ic (W25Q40CLSNIG-Winbond), etc... Since this is bare ic, i dont know whether boot loader is present already or not, so i tried to burn bootloader with the following connections using TTL converter,

vcc - 3.3v
gnd - gnd
tx - rx
rx-tx
en- 3.3v (with external pull up)
gpio0 - gnd

my settings in arduino ide as follows,
board : ESP32 dev module
programmer: AVRMSP mk11
Ide version : ARDUINO1.8.9 Hourly build
Java version : java 8 update 261

but i m not able to burn bootloader into the ic. please help me to solve the issue. After burning the bootloader, i need to flash my own program into it.

i have shared my schematics.

Thanks in advance !

The bootloader for the ESP32 is in ROM; you cannot and do not need to burn it. I see you connect EN to 3.3V; this won't work as the ESP32 needs a reset pulse to get it started. Suggest you follow the hardware design guidelines on the schematic needed there instead; basically, you'll also need a capacitor from CHIP_PU to Gnd.

thank you for the reply.. i will try your suggesstion. but gave the same connections as mentioned above to the esp32 module (please refer the attachment) . it works very well.
i do not understand this. please explain me.

Hard to say. Do you get any activity on the serial port at all?

No I didn't get any response from the esp32 on the terminal. Instead I m getting error.
Error : "A fatal error occurred : Failed to connect esp32: Timeout waiting for the packet"

Can you see the crystal oscillating at 40MHz?

Yes. Now I have replaced the working Ic on the same board. But now it is working fine. From this I can able to understand there is a problem in the bootloader ( not entering into bootloader). Is my understanding correct ?

It depends. If your ESP32 is working (and GPIO15 is not grounded), you always should see some kind of boot message on the UART. If you don't see that, something more basic is going on. If you see that but you cannot upload a program, likely something is going wrong with entering download mode.

Thanks for the explanation. But how to fix this error (not entering download mode) in my new ic. Should I burn a bootloader again ? Please suggest me a way to fix this.
Thank you.

is there any way to burn a bootloader for esp32 using arduino uno ? (arduino uno as ISP programmer) ...