ESP8266 Community Forum

- Wed Mar 31, 2021 4:33 am #90994

Yes. That schematic adds on the USB to serial and extra components to allow for automatic flashing.

It looks Ok but I would use a slightly lower value for the pull down on GPIO15. After reset GPIO15 will have a weak internal pull up of around 36K. The 12K value of the pull down will drop the voltage down to 0.25 of Vcc which will probably be read as a low but the specification says it should be below 0.25Vcc so it is marginal and if the internal pull up is a bit lower then it would be out of spec. . I would use 4k7 to be really sure it is a good solid low.

Hi, I have changed the resistance of the GPIO15 from 12k to 4.7k.

I wanted to ask you some questions:
What is the "1N5819" (VVDDUSB - 1N5819 - VDD5V) used for?
Now if I print this scheme, should everything work correctly?
Is there a way to simulate it before printing?
How to program without the NodeMcu?

Thank you so much for everything

Oscar

- Wed Mar 31, 2021 7:04 am #90996 The 1N5819 (schottky diode) is there as a protection measure in case you try to externally power it while it is also connected to USB.

The circuit looks good.

I don't know of any simple way to simulate it.