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Boot Process

jcmvbkbc edited this page Nov 17, 2014 · 13 revisions

Overview

  • Reset vector is 0x40000080.
  • Boots into Xtensa XTOS code in IROM0.
  • Transfers control to Espressif code in IROM0.
  • Starts executing ESP SDK-code shadowed SPI ROM (unconfirmed).

ESP Boot Modes

The Espressif code can boot in different modes, selected on power-up based on GPIO pin levels.

MTDO GPIO0 GPIO2 Mode Description
L L H UART Download code from UART
L H H Flash Boot from SPI Flash
H x x SDIO Boot from SD-card

References