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Appendix A

Appendix A – ESP32 Pin Lists

A.1. Notes on ESP32 Pin Lists

Table 24: Notes on ESP32 Pin Lists

No.

Description

In Table IO_MUX, the boxes highlighted in yellow indicate the GPIO pins that are input-only.

Please see the following note for further details.

GPIO pins 34-39 are input-only. These pins do not feature an output driver or internal pull-

up/pull-down circuitry. The pin names are: SENSOR_VP (GPIO36), SENSOR_CAPP (GPIO37),

SENSOR_CAPN (GPIO38), SENSOR_VN (GPIO39), VDET_1 (GPIO34), VDET_2 (GPIO35).

The pins are grouped into four power domains: VDDA (analog power supply), VDD3P3_RTC

(RTC power supply), VDD3P3_CPU (power supply of digital IOs and CPU cores), VDD_SDIO

(power supply of SDIO IOs). VDD_SDIO is the output of the internal SDIO-LDO. The voltage of

SDIO-LDO can be configured at 1.8 V or be the same as that of VDD3P3_RTC. The strapping

pin and eFuse bits determine the default voltage of the SDIO-LDO. Software can change the

voltage of the SDIO-LDO by configuring register bits. For details, please see the column “Power

Domain” in Table IO_MUX.

The functional pins in the VDD3P3_RTC domain are those with analog functions, including the

32 kHz crystal oscillator, ADC, DAC, and the capacitive touch sensor. Please see columns

“Analog Function 1

~3” in Table IO_MUX.

These VDD3P3_RTC pins support the RTC function, and can work during Deep-sleep. For

example, an RTC-GPIO can be used for waking up the chip from Deep-sleep.

The GPIO pins support up to six digital functions, as shown in columns “Function 1

~6” In Table

IO_MUX. The function selection registers will be set as “N-1”, where N is the function number.

Below are some definitions:

• SD_* is for signals of the SDIO slave.

• HS1_* is for Port 1 signals of the SDIO host.

• HS2_* is for Port 2 signals of the SDIO host.

• MT* is for signals of the JTAG.

• U0* is for signals of the UART0 module.

• U1* is for signals of the UART1 module.

• U2* is for signals of the UART2 module.

• SPI* is for signals of the SPI01 module.

• HSPI* is for signals of the SPI2 module.

• VSPI* is for signals of the SPI3 module.

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