What exactly is CAPP, CAPN, VP, and VN?

[AlohaSpark]

I received footprints for the ESP32-PICO-D4 that had these grouped together:


The ESP32 datasheet and the ESP32-PICO-D4 datasheet do not mention anything detailed about them.
https://www.espressif.com/sites/default ... eet_en.pdf
https://www.espressif.com/sites/default ... eet_en.pdf

However, there are capacitors between VP/CAPP and VN/CAPN in the hardware design guidelines (page 12, 2.1.5)
https://www.espressif.com/sites/default ... nes_en.pdf

What are they for? Is it a tuner/filter for the ADC? Are the pins really just GPIO and ADC, or can we use them for something else?

These are two of the few results on Google that mention CAPP and CAPN:
Page 2 of https://www.onsemi.com/pub/Collateral/AX2061-D.PDF
Pages 15 and 16 of https://cdn.datasheetspdf.com/pdf-down/ ... grated.pdf

[ESP_Sprite]

These are for an on-board LNA for the ADC; unfortunately, there were issues with the LNA and the feature got dropped from the datasheet. You can still use the pins as digital inputs (or ADC pins if you don't use WiFi)

[AlohaSpark]

These are for an on-board LNA for the ADC; unfortunately, there were issues with the LNA and the feature got dropped from the datasheet. You can still use the pins as digital inputs (or ADC pins if you don't use WiFi)

Oh, I see. That's interesting. It's good to know the story behind it. Thank you!

Perhaps the datasheets could be updated in the future.

[ESP_krzychb]

LNA is my favorite hidden not supported ESP32 peripheral.
More about it https://github.com/krzychb/esp32-lna