ESP32-PICO-D4 Reference Board Schematic

[dracode]

Hello,

I'm interested in doing my own simple PCB layout with an ESP32-PICO-D4 onboard.

Is there a reference schematic that notes recommended layout, supporting hardware, and so on?

I know it's supposed to be basically a completely self-contained module, but even the "minimal" tiny design whose image is on all the blogs appears to have a few small passives on the board (maybe 2 caps and a diode?). Is that just for smoothing power ripples? Are there recommended values? etc.

Looking for a simple schematic similar to what you might find in an "application note" in the data sheet for other ICs.

Thanks!

[iot-bits.com]

I've made some ESP-PICO-D4 boards, maybe I would write a little design blog. Good idea!

[dracode]

That would be great!

In fact, yours is one of the blogs that shows the "minimal" design I mentioned, in your August 26th post.

If you do write such a design blog post, I'd definitely read it.

[ESP_Angus]

Is there a reference schematic that notes recommended layout, supporting hardware, and so on?

There is a schematic on Section 6 of the datasheet:
http://espressif.com/sites/default/file ... eet_en.pdf

(The antenna matching components are marked TBD because their selection will depend on the antenna selection.)

[dracode]

Oh, there sure is. I'm not sure how I missed that, thank you.

I guess I'll have to read up on antenna matching circuits.

[dracode]

Okay, after some reading... I think the antenna matching circuitry is only required if there's an impedance mismatch between the transmitter and antenna.

The ESP's datasheet says its output impedance is 50 Ohms.
The antenna I'd planned to use is the RainSun AN9520, the same ceramic chip antenna found on some of the ESP8266 boards. The datasheet for the AN9520 says its input impedance is also 50 Ohms.

Therefore, I think I do not need a matching network. Is that a valid assumption?


Second question:
There are three VDDA pins. two VDDA3P3 pins, and a VDD3P3_RTC pin.
Is it actually necessary to run power traces to all six of these pins? Or can I safely leave some of the "duplicate" pins unconnected?