[solved] Reset: is a 10K resistor required ?

[nounours18200]

Hi,

I use an ESP32 Pinboard and on this page:
https://www.14core.com/wiring-and-flash ... -ttl-uart/

it is shown that there is a 10K resistor between the +3.3V power supply and the RESET button.

The RESET button can be soldered on the pinboard, but this 10K is not present on the Pinboard, and if I solder one out of the piboard, it becomes useless to have the reset button on the pinboard.

Is this 10K resistor required ? if the reset simply consists to pull down the EN pin to Ground, I do not see why we need this resistor ?

Thank you

[ESP_krzychb]

Is this 10K resistor required ? if the reset simply consists to pull down the EN pin to Ground, I do not see why we need this resistor ?

Hi nounours18200,

You add a resistor because a floating pin is subject to electrical noise which could cause random resets.

[nounours18200]

because a floating pin is subject to electrical noise which could cause random resets

It is exactly what I meant, and I supposed that when RESET is engaged, the value of R is so high (10K) that there is no risk of short circuit: I=U/R = 5/10000 = 0.5mA

By the way, do I have to maintain RESET engaged all along the flashing process, or just at the begining ??

[mikemoy]

By the way, do I have to maintain RESET engaged all along the flashing process, or just at the begining ??

If its held in reset, how could you flash it?

https://github.com/espressif/esptool/wi ... -Selection

[nounours18200]

Sorry, it was stupid... (I made a confusion between Reset and I00 connected to ground...)

Thank you for your replies,
Michel

[mikemoy]

No sweat.... To answer your question is yes you can keep it low during flashing.

[nounours18200]

you can keep it low during flashing

Do I can or do I must: I mean is a temporary pull down to GND is enough to start the flashing process of the firmware a few seconds later ?

All the articles that I have read shows a I00 permanently to GND all along the flashing process....


Thank you,

[mikemoy]

Either way is ok.
Whats is happening is when it comes out of reset, its checks GPIO0 state. If high then it boots up normally. If low then it goes into flashing mode.

So, just as long as GPIO0 is low BEFORE reset (EN PIN) returns high your in flashing mode.

[nounours18200]

Thank you very much Mikeymoy: it is cristal clear !