IO0 / EN minimum/maximulm timing

[adesandr]

Hello,

I have developed a board based on ESP-WROOM-32, whose objective is to be inserted in a box to measure the control surface deflection for RC planes and gliders. The system works with two boxes connected by Wifi (one of the boxes being AP and the other station) and a web app embedded in the AP box allows to display the deflections and gaps between two identical control surfaces. The project is in open source and is described at the following address (schematic, gerber and stl for the box): https://github.com/adesandr/GliderThrow_Meter.

I just have a small problem: the card does not reset itself on power on, I have to press the reset button to reset. By reading the forums and datasheets, I have the impression that my problem comes from the timing between the 3,3V and the rising edge on the EN pin. I put the RC circuit indicated on EN (R=10k and C = 0,1uF)

I have not yet put an oscilloscope, but I can't find in the datasheet of expressif the timing (min, max) between the establishment of the 3,3v and the rising edge on the EN pin, so that EN is correctly taken into account.

Here is the schematic of my board. Thank you very much in advance for the time you will spend to help me.

schematic.PNG (490.22 KiB) Viewed 5017 times

pcb-v0.png (422.75 KiB) Viewed 5017 times

Regards.

[username]

I have not checked your schematic, but have you checked to make sure your not having any of the bootstrap pins in the wrong state on powerup?

Check this guide.

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

[adesandr]

Hello, yes i’ve ckecked it.

Maybe C18 is not the good value (RC circuit on EN). R = 10k and C = 0.1uF. There are the value proposed in the espressif DevKitC schematic. GPIO2 is floating. I’ve red on the espressif Github that a value of 1uF is recommanded for C, maybe my problem is on this value. Any opinion will be appreciate.

Tia.

[boarchuz]

It might help to remove C5 (for faster IO0 rise time).

[username]

You reset circuit is fine. Though there really is no need for C12. Using C18 is enough.
You probably do not need C5.
If I had to guess, I would look into your IC1 circuit. It might not be resetting properly and holding your EN or GPIO0 low when powered up.