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Boot Process

tommie edited this page Nov 15, 2014 · 13 revisions

Overview

  • Reset vector is 40000000h (unconfirmed).
  • Boots into Xtensa SROM (unconfirmed).
  • Transfers control to Espressif code in IROM0 (unconfirmed).
  • 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