ESP32 Forum

I'm working on a custom board whose main processor is an ESP32.
I hooked up the bare minimum I could think of to make the esp power on, but nothing seems to be sent on uart0.
I have the 3.3v pins (vdda, vdd3p3, vdd3p3_rtc, vdd3p3_cpu), gnd, chip_pu with an external 10k pull-up and u0tx hooked up to a rs232r uart to USB converter. Everything else is left floating.
I see nothing on the serial console on the pc when I touch chip_pu to ground.

Is there anything that I'm missing? Any additional connections?

What kind of 'esp32' are you using? The ESP32 itself is just a chip, and you need more than what you mentioned to get that to run (antennal, crystal, handful of R's and C's, ...)

ESP-D0WDQ6

I don't plan on using the wifi/bl features so I didn't add neither an antenna, neither an external 40mhz clock.
I have decoupling caps on all 3v3 pins and 42uF + 10uF near vdd3p3 (pin 3 and 4).

You do need an external crystal, I don't think the ESP32 can boot up from the internal oscillator. Furthermore, you probably need a flash chip to store your program in, as well as the stuff around CAP1/CAP2, plus perhaps more; check here for more info.