Component Pin Classification

1:25

Revising search strategy.

Espressif encountered an error.

From the Espressif datasheet for this module, here are the pin groups you asked for:

Bootstrap pins

These are the module strapping pins used at reset:

IO0 - module pin 27
IO45 - module pin 26
IO46 - module pin 16

What they control:

IO0 + IO46: boot mode
IO45: VDD_SPI voltage selection
IO46: ROM message printing

Input-only pins

IO46 - module pin 16 - type I

That is the only pin in the module pin table marked input-only.

USB pins

IO19 - module pin 13 - USB_D-
IO20 - module pin 14 - USB_D+

Pins connected to internal memory

There are two useful interpretations here:

These pins are labeled with FSPI/SPIIO functions in the module pin table:

IO9 - pin 17 - FSPIHD
IO10 - pin 18 - FSPICS0 / FSPIIO4
IO11 - pin 19 - FSPID / FSPIIO5
IO12 - pin 20 - FSPICLK / FSPIIO6
IO13 - pin 21 - FSPIQ / FSPIIO7
IO14 - pin 22 - FSPIWP / FSPIDQS
IO33 - pin 24 - SPIIO4 / FSPIHD
IO34 - pin 25 - SPIIO5 / FSPICS0
IO35 - pin 28 - SPIIO6 / FSPID
IO36 - pin 29 - SPIIO7 / FSPICLK
IO37 - pin 30 - SPIDQS / FSPIQ
IO38 - pin 31 - FSPIWP

2. Pins actually reserved on the chip side for in-package flash/PSRAM

The ESP32-S2 chip datasheet says the pins allocated for communication with in-package flash/PSRAM should not be used for other purposes. On the chip, these are the dedicated SPI memory pins such as:

SPICS0
SPIHD
SPIWP
SPICLK
SPIQ
SPID
and, for wider memory modes, GPIO33-GPIO37

On the module, the always-reserved internal flash connections are generally internalized rather than simply exposed as ordinary user pins, so if your goal is a safe "do not use casually" list, the cautious exposed-pin set is:

Table

Category	Pins
Definitely strapping-sensitive	IO0, IO45, IO46
USB-fixed by default	IO19, IO20
Memory-related / use with caution	IO33, IO34, IO35, IO36, IO37
Memory-bus alt-function pins also shown in pin table	IO9, IO10, IO11, IO12, IO13, IO14, IO38

If you want, I can also turn this into a clean Flux terminal classification table with columns like Pin Name / Pin Number / Pin Type / Section / Pin Group / Notes for your part project.

List EPAD pin groups

Include exact pin names

Make a pin table

a day

IO38

IO21

IO19

IO11

IO35

IO9

IO6

IO4

3V3

IO45

IO40

RXD0

EPAD

IO13

IO12

IO7

IO20

IO41

IO1

GND

TXD0

IO8

EPAD

IO33

IO46

IO17

IO0

IO34

EPAD

IO15

IO2

IO3

IO37

IO14

IO42

IO5

IO36

EPAD

IO16

IO39

IO10

IO18

Reviews

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