Replacing crystal with clock from another esp32 - WiFi stops working

[greengnu]

So from some posts I gathered that it should be possible to replace the crystal with a crystal oscillator or other clock source by connecting tge clock output directly to XTAL_P and letting XTAL_N floating.

I tried this here with an esp32-c3 supermini. I removed the crystal and then output CLKOUT_SIG_XTAL from an esp32-s3 supermini to the XTAL_P pin of the c3.

IMG_1981.jpeg (2.26 MiB) Viewed 276 times

S3 on top, C3 on bottom.

This works, the C3 boots up, however it's not able to connect to wifi anymore. The clock output looks clean on my amateur scope (120Mhz bandwidth):

IMG_1980.jpeg (2.09 MiB) Viewed 276 times

Any idea what could be the reason for wifi not working anymore?

[mikemoy]

You cannot run a clock signal via a unshielded piece of wire right next to the Wi-Fi antenna.
It should be shielded!!

[greengnu]

thanks - even if I place the wire away from the antenna in the opposite direction wifi isn't connecting (the crystal XTAL-P pin is also unshielded and if I move the cable away that pin is the closest thing to the antenna). I also notice the esp32-c3 IC getting pretty hot

[MicroController]

If WiFi/BT don't work, it's likely because the clock frequency is off.

At least for the S2, the docs say:

If an oscillator is used, its output should be connected to XTAL_P on the chip through a DC blocking capacitor (about 50 pF).

Maybe give that a try.