Holding button during flashing ESP

Deouss
Posts: 278
Joined: Tue Mar 20, 2018 11:36 am

Holding button during flashing ESP

Postby Deouss » Mon Jun 11, 2018 1:41 pm

I just bought some cheap pcb boards with usb to ttl converter and nice buttons.
After soldering esp chip and testing board I noticed I have to hold the key button and all was fine.
I have another firebeetle board and it doesn't need that.
What is the rule or reason for that? Does it depent on the onboard chip or design?
Or is it type of built in feature on the esp chip or usb?

WiFive
Posts: 2062
Joined: Tue Dec 01, 2015 7:35 am

Re: Holding button during flashing ESP

Postby WiFive » Mon Jun 11, 2018 7:47 pm

Yes there is a special boot circuit and not all boards have it

Deouss
Posts: 278
Joined: Tue Mar 20, 2018 11:36 am

Re: Holding button during flashing ESP

Postby Deouss » Mon Jun 11, 2018 10:46 pm

Can you tell me more what circuit it is?
What should I look for?

WiFive
Posts: 2062
Joined: Tue Dec 01, 2015 7:35 am

Re: Holding button during flashing ESP

Postby WiFive » Mon Jun 11, 2018 10:55 pm

Image

Basically the parts to the left of the USB bridge label

Deouss
Posts: 278
Joined: Tue Mar 20, 2018 11:36 am

Re: Holding button during flashing ESP

Postby Deouss » Tue Jun 12, 2018 12:03 am

So I am guessing it is all on the uart\usb chipset.
Like a built-in feature than comes with IC

ESP_Angus
Posts: 1267
Joined: Sun May 08, 2016 4:11 am

Re: Holding button during flashing ESP

Postby ESP_Angus » Tue Jun 12, 2018 1:16 am

Deouss wrote:So I am guessing it is all on the uart\usb chipset.
Like a built-in feature than comes with IC
No, some additional circuitry is added (where WiFive mentions, look for the label on the PCB itself) to coordinate the automatic reset.

You can read about the details here:
https://github.com/espressif/esptool/wi ... bootloader

If you download (for example) the ESP32-DevKitC-V4 reference design from the downloads page and open the reference schematic PDF, you can see the equivalent connections in the bottom left of the page/

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