Component Pin Classification

flux

I checked the Espressif datasheet for ESP32-PICO-MINI-02U. Here are the pin groups you asked for:
Bootstrap / strapping pins
These are sampled at reset for boot configuration:

Table

Module PinSignalNotes
19IO12 / MTDIStrapping pin, also affects VDD_SDIO voltage
21IO15 / MTDOStrapping pin, also affects boot log output
22IO2Strapping pin
23IO0Strapping pin, boot/download mode control
29IO5Strapping pin
Input-only pins
These pins are input-only, not bidirectional GPIO:

Table

Module PinSignalFunctions
4I36 / GPIO36ADC1_CH0, RTC_GPIO0
5I37 / GPIO37ADC1_CH1, RTC_GPIO1
6I38 / GPIO38ADC1_CH2, RTC_GPIO2
7I39 / GPIO39ADC1_CH3, RTC_GPIO3
9I34 / GPIO34ADC1_CH6, RTC_GPIO4
10I35 / GPIO35ADC1_CH7, RTC_GPIO5
8ENChip enable input only
Pins connected to internal memory
The module datasheet says some chip pins are used internally and are not led out on the module, while others are brought out but are tied to in-package flash/PSRAM and are not recommended for other use.
Not led out on the module

Table

Chip SignalInternal Use
CMD / IO11Embedded flash
CLK / IO6Embedded flash
SD2 / IO9Embedded PSRAM
SD3 / IO10Embedded PSRAM
Brought out on the module, but connected to internal flash/PSRAM

Table

Module PinSignalInternal Connection
27IO7HS1_DATA0 / flash-related bus
28IO8HS1_DATA1 / flash-related bus
30RXD0 / GPIO3Not internal memory
31TXD0 / GPIO1Not internal memory
More specifically from the module schematic, these internal memory-related connections are:
  • IO23 -> SPIDI
  • IO18 -> SPIWP
  • CLK -> FLASH_CLK
  • CMD -> FLASH_CS
  • SD3 -> PSRAM_CLK
  • SD2 -> PSRAM_CS
  • IO17 -> SPIDO
  • IO16 -> SPIHD
So for practical pin-classification in your part:
  • Definitely internal-memory reserved / not for general use: IO6, IO9, IO10, IO11
  • Also involved in the internal flash/PSRAM interface in the module schematic: IO16, IO17, IO18, IO23
USB pins
This module does not have native USB data pins exposed in the datasheet pin table.
  • No USB_DP
  • No USB_DM
  • No native USB interface pins listed
So the USB pins list is empty for this part.
Short summary

Table

CategoryPins
Bootstrap pinsIO0, IO2, IO5, IO12, IO15
Input-only pinsGPIO34, GPIO35, GPIO36, GPIO37, GPIO38, GPIO39, plus EN as input
Internal-memory connected / reservedIO6, IO9, IO10, IO11; also module memory interface uses IO16, IO17, IO18, IO23
USB pinsNone
If you want, I can turn this into a pin classification table for all 53 pins next.
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Files

Pins

Symbol

Layout

Preview

IO21
IO33
IO32
IO25
IO27
IO4
IO8
IO19
IO13
IO14
IO22
IO7
IO20
IO26
Name
Pin #
Type
Part Type
Pin Orientation
Section
Terminal Order
Terminal Type
GND
1
Unspecified
Terminal
Left
GND
10
powerIn
GND
2
Unspecified
Terminal
Bottom
GND
10
powerIn
3V3
3
Unspecified
Terminal
Top
POWER
1
powerIn
I36
4
Unspecified
Terminal
Left
INPUT ONLY
4
INPUT
I37
5
Unspecified
Terminal
Right
INPUT ONLY
4
INPUT
I38
6
Unspecified
Terminal
Right
INPUT ONLY
4
INPUT
I39
7
Unspecified
Terminal
Right
INPUT ONLY
4
INPUT
EN
8
Unspecified
Terminal
Left
PROGRAMMING
2
INPUT
I34
9
Unspecified
Terminal
Left
INPUT ONLY
4
INPUT
I35
10
Unspecified
Terminal
Left
INPUT ONLY
4
INPUT
GND
11
Unspecified
Terminal
Right
GND
10
powerIn
IO32
12
Unspecified
Terminal
Right
GPIO
6
bidi
IO33
13
Unspecified
Terminal
Right
GPIO
6
bidi
GND
14
Unspecified
Terminal
Right
GND
10
powerIn
IO25
15
Unspecified
Terminal
Right
GPIO
6
bidi
IO26
16
Unspecified
Terminal
Right
GPIO
6
bidi
IO27
17
Unspecified
Terminal
Right
GPIO
6
bidi
IO14
18
Unspecified
Terminal
Left
GPIO
6
bidi

ESP32-PICO-MINI-02U

ESP32-PICO-MINI-02U thumbnail