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ESP8266 Boot - Revision history
2026-06-05T11:37:21Z
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Chao at 07:20, 4 June 2021
2021-06-04T07:20:42Z
<p></p>
<p><b>New page</b></p><div>== Boot Options ==<br />
| GPIO 0 | GPIO 2 | GPIO 15 (MTDO)<br />
----------------------------------|--------|--------|---------<br />
Flash Startup (Normal) | 1 | 1 | 0<br />
UART Download Mode (Programming) | 0 | 1 | 0<br />
SD-Card Boot | 0 | 0 | 1<br />
<br />
Only use Flash Boot and Download Mode<br />
| GPIO 0 <br />
----------------------------------|--------<br />
Flash Startup (Normal) | 1 <br />
UART Download Mode (Programming) | 0<br />
<br />
{| class="wikitable sortable"<br />
|-<br />
! Header text !! Header text !! Header text<br />
|-<br />
| ESP-12F || <br />
* pull GPIO15 low<br />
* GPIO2 high <br />
* EN high<br />
|| GPIO0 for mode<br />
|-<br />
| ESP-12S|| -|| GPIO0 for mode<br />
<br />
|}<br />
<br />
<br />
<br />
== Enter Into Flash Mode ==<br />
* Most development board has auto enter into flash mode circuits, more commerial products do not really need this.<br />
* '''Pull GPIO 0 of ESP8266 before power up or reboot''' to enter into flash mode. -> So simply hold down GPIO 0 and press once reset will enter into flash mode manully.<br />
* Connect 3.3V/GND/TXD=>RXD/RXD->TXD to target, recommand [[USB-TTL]] downloader here<br />
<br />
<br />
<gallery><br />
File:Nwi1072_esp_relay_board_wiring_for_prog.JPG | NWI1072 ESP Relay board, enter into flash mode.<br />
File:Esp8266 setup 01.png | For our ESP8266 Adapter Board<br />
File:Serial debug 03.gif | See a GIF here, if you successfully enter into flash mode. <br />
File:Esp8266_setup_02.png | debug info shows enter into flash mode<br />
</gallery><br />
<br />
<br />
<br />
== Boot Debug ==<br />
<br />
* Open arduino IDE, and set baud rate to 74880 on serial, can find esp8266 debug info.<br />
<br />
ets Jan 8 2013,rst cause:1, boot mode:(3,6)<br />
<br />
load 0x4010f000, len 1384, room 16 <br />
tail 8<br />
chksum 0xef<br />
csum 0xef<br />
csum err<br />
ets_main.c <br />
* reset causes:<br />
0: <br />
1: normal boot<br />
2: reset pin<br />
3: software reset<br />
4: watchdog reset<br />
<br />
* boot device:<br />
0:<br />
1: ram<br />
3: flash<br />
== Flash Error Log ==<br />
* flash size is not correctly selected, in this case should be 16Mbit-C1 instead of 32Mbit<br />
mismatch map 5,spi_size_map 4<br />
system_partition_table_regist fail<br />
=== Incorrect flash mode ===<br />
ets Jan 8 2013,rst cause:1, boot mode:(3,7)<br />
<br />
load 0x4010f000, len 1384, room 16 <br />
tail 8<br />
chksum 0xef<br />
csum 0xef<br />
csum err<br />
ets_main.c<br />
* Fix:esptool.py write_flash 0x0 Yxxxx.bin<br />
* change to below, add dout SPI flash mode<br />
esptool.py write_flash --flash_mode dout 0x0 Yxxxx.bin<br />
<br />
== Debug ==<br />
=== Hardware Check ===<br />
* Try to swap TXD and RXD in case it is wrong <br />
* Buttons should be hold down or pressed firmly and properly to make the good connection, it is too tiny button <br />
* On module status Blue LED will blink once on reset<br />
* USB-TTL Compatible with 5V TXD RXD signal, for our relay boards, wiring should be 5V, GND, TXD and RXD. Recommanded USB-TTL debugger boards are CP2102, speed up to 15000000 (Some other boards only do 115200)<br />
<br />
=== Software Correct Boot Mode Output ===<br />
* Correct flash mode output on arduino baudrate 748800: <br />
ets Jan 8 2013,rst cause:2, boot mode:(1,7)<br />
* Correct normal boot mode output <br />
ets Jan 8 2013,rst cause:2, boot mode:(3,7)<br />
<br />
<br />
[[category: ESP8266 Program]]</div>
Chao