Cannot seem to enter Boot mode using the esptool!

[RamiMehyar]

I have built a custom board with an ES32-S2 chip, I am trying to upload a test sketch to it using the UART and an FTD2204 adapter. It does seem to toggle the IO0 and EN correctly, but it seems it is timing out as folows:

A fatal error occurred: Failed to connect to ESP32-S2: Timed out waiting for packet header

Are ESP32-S2 bare chips missing the bootloader?

attached also my schematics, can anyone please help? I am frustrated, I have tried everything.

[lbernstone]

Are you seeing anything on the serial monitor? You should see a boot loop if there is no firmware at all installed. You should see "waiting for download" if gpio0 is pulled to ground.
If not, you either have an issue with the serial lines, or else you are not supplying adequate power to the device.

[RamiMehyar]

Thank you for trying to help! No, i do not see anything on the monitor! Did you take a look at the power rails on the schematics? Do you think there is something wrong with it?
The power comes currently from the ESP-prog which i have read has an adequate power supply.

[lbernstone]

I would put it on a bench power supply and watch the draw at boot. It should be using ~80mA, with a small cyclical increase as it attempts to access the flash on each reboot. Make sure that when you ground the EN pin that the power goes near zero.

[RamiMehyar]

Wierd, its pulling 6.7 mA constant and 3.1 mA when i pull EN LOW. And EN goes to 0 V when i pull it down.

[RamiMehyar]

My bad guys, i didnt know that a xtal was mandatory to run the chip, i didnt have it on my design if you could notice from the schematics. I have to redesign my board...
I have the esp32-s2 with the embedded 4mb rom and 2mb ram, is the external flash rom mandatory in this case?

[ESP_Sprite]

I have the esp32-s2 with the embedded 4mb rom and 2mb ram, is the external flash rom mandatory in this case?

No. You shouldn't supply external flash on the flash pins when the part has internal flash.