Default value of EN Pin [ESP32 S3 N16R8]

[raprakashvi]

We have been extensively using the ESP 32 S3 Wroom 1 module in our research and design of products for research. In the recent design (files attached) we notice that the EN pin is always in Low state by default and the board does not work until we connect the EN to high (and then it works). My understanding is that EN is supposed to be high by default. Can you please check the circuit and point out any issue that you see? I have not connected it to GND anywhere before the "reset" button. Does the button quality has a role to play?

Thanks a lot.

[Sprite]

My understanding is that EN is supposed to be high by default.

Your understanding is wrong. EN on the chip/module side is floating and it needs a RC network on it to provide a proper power-on reset, usually something like an 10K to 3.3V and an 1uF to ground.

You also want to remove C11, by the way: it makes IO0 be grounded when the circuit is powered on meaning the chip will boot into download mode rather than start executing its firmware. Your TP4056 circuit also seems to miss a lot of external components and will never charge the battery on U12 as it's drawn now.

[eriksl]

My $0.02: I've found that pins like RST and EN need to be decoupled from the power supply as well, besides having some delay after start. For that I connect them using a 10 k resistor to Vcc and then add a small ceramic capacitor (like 100 nF) between ground and the relevant pin. This looks remarkably like the RC circuit Sprite referred to (and can be served with the same components), but has a difference purpose: I've found that any spike (up or down) on the power supply may cause the chip to detect a reset condition. This was especially true on the ESP8266, I haven't seen it on the ESP32 (yet). The spike may be generated by a large inductive load being switched on or off nearby (e.g. TL tubes or a hair dryer). I am not sure whether the load or the switching is the culprit, but it's very easy to crash an ESP8266 that way, if not taken good care of. This is not caused by a "brown-out" (reset cause says: "user reset").

[raprakashvi]

This is very helpful. thanks a lot. Any recommendations on TP4056 circuit?