Public
Authored by Jens Nolte

ESP32 Pin Notes

Mostly from https://github.com/espressif/esptool/wiki/ESP32-Boot-Mode-Selection

Bootloader

Pin bootloader functionality Connect serial for esptool.py (automatic reset)
EN connect to serial RTS
GPIO0 has pullup, low to enter bootloader connect to serial DTR
TX (GPIO1) connect to serial RX
RX (GPIO3) connect to serial TX
GPIO2 must be floating or low to enter bootloader
GPIO5 (SDIO settings)
GPIO12 has pulldown, low = 3.3V
GPIO15 has pullup, low to silence boot messages

General

Pin general notes
GPIO6-11 usually used for SPI flash
GPIO34-39 input only, no pullup/pulldown

Ethernet

Pin (ESP) Pin (Phy) Notes
EMAC_TX_CLK (GPIO0) RETCLK
EMAC_TXD0 (GPIO19) TX0
EMAC_TXD1 (GPIO22) TX1
EMAC_RXD0 (GPIO25) RX0
EMAC_RXD1 (GPIO26) RX1
EMAC_TX_EN (GPIO21) TX-EN
EMAC_RX_DV (GPIO27) CRS
any GPIO MDC any gpio-mux gpio
any GPIO MDIO any gpio-mux gpio
any GPIO or EN circuit OSC_DIS ("NC") high or floating at boot
Edited
15 Bytes
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