ESP32 Bootstrap Pins Explained

1:53

Looking for "Which pins are input only on the ESP32-S3-WROOM-1 / ESP32-S3-WROOM-1-N4R8? Identify GPIOs that are input-only and cannot be used as outputs." in esp32_s3_wroom_1_wroom_1u_datasheet_en-2930317.pdf

Looking for "Find the GPIO summary or pin description section for ESP32-S3-WROOM-1. Which GPIOs are input-only?" in esp32_s3_wroom_1_wroom_1u_datasheet_en-2930317.pdf

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On this module, the input-only GPIO is GPIO46 / IO46.

In Flux terms, an Input pin means input-only, while Bi-Directional / I/O means it can be used as both an input and an output . So the practical distinction you care about is:

Table

Pin	Use
`IO46`	Input only
Most other exposed `IOx` pins	Can be used as normal GPIO input/output

A few practical notes:

IO46 is not a good choice for driving LEDs, chip selects, enables, or any other output signal.
It can still be used for things like button inputs, status inputs, interrupt inputs, etc.
IO46 is also one of the strapping pins, so be careful not to force it to the wrong level during reset/boot.

If you want, I can give you a safe GPIO cheat sheet for this module:

safe general-purpose pins
bootstrap pins to avoid
USB/JTAG-sensitive pins
unavailable pins on the N4R8 variant.

Check selected pins

Show pin restrictions

Recommend safe usage

3 days

IO41

IO4

IO20

GND_5

IO18

IO1

IO11

IO7

IO15

IO19

GND_10

IO35

IO37

IO8

IO2

GND_6

GND_8

IO14

IO42

GND_7

IO5

IO40

IO39

GND_9

IO6

IO12

IO38

IO9

IO16

IO13

GND_2

IO21

IO10

GND_4

GND_3

IO47

GND_1

IO48

IO17

IO36

GND_11

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