Esptool is a tool to create firmware files for the ESP8266/ESP32 chips and flash the firmware to the chip over serial port. Esptool runs on Windows, Linux and Mac OS X.

Esptool reads the compiled program in ELF format, extracts code and data sections, and either dumps a section to a file or assembles the firmware file from several segments. Esptool also communicates with the bootloader to upload firmware files to flash. Esptool can automatically put the board into UART bootloader mode using a variety of methods.

Linux	Windows

Usage

esptool <arguments>

The program interprets the arguments given on the command line, and in the order they are given. The following commands are currently available:

Argument	Description
-eo <filename>	Open an ELF object file, parse it and cache some of the information found therein. Works only if there is no ELF file currently opened.
-es <section> <filename>	Read the given section from the ELF file and make a raw dump into the specified file.
-ec	Close the currently opened ELF file
-bo <filename>	Prepare a firmware file in the format that is understood by the ESP chip. Works only if an ELF file is opened, and if no firmware file is prepared yet. Upon -bo the tool will start out with an empty image where only the main header is set up. The result of the operations done on the firmware image is saved when the it is finally closed using -bc command.
```-bm <qio	qout
```-bz <512K	256K
```-bf <40	26
-bs <section>	Read the specified section from the ELF file and append it to the firmware image. Sections will appear in the firmware image in the exact same order as the -bs commands are executed.
-bp <size>	Finalize the firmware image, padding it with 0xaa value until it is at least <size> bytes long. Unlike -bc, this doesn't close the file. This option can be used to combine bootloader with the rest of the application
-br <size>	Pad all the following sections to multiples of <size>. Default is 4 bytes. This option can be used to place sections on specific boundaries, e.g. 4k or 64k.
-bc	Close the firmware image and save the result as file to disk.
-v	Increase verbosity level of the tool. Add more v's to increase it even more, e.g. -vv, -vvv.
-q	Disable most of the output.
-cp <device>	Select the serial port device to use for communicating with the ESP. Default is /dev/ttyUSB0 on Linux, COM1 on Windows, /dev/tty.usbserial on Mac OS X.
-cd <board>	Select the reset method to use for resetting the board. Currently supported methods are listed below.
-cb <baudrate>	Select the baudrate to use, default is 115200.
-ca <address>	Address in flash memory to upload the data to. This address is interpreted as hexadecimal. Default is 0x00000000.
-cf <filename>	Upload the file to flash. Parameters that set the port, baud rate, and address must preceed the -cf command.
-ce	Erase flash
-cr	Reset chip into app using the selected reset method
-cc <chip>	Select chip to upload to. Currently supported values: esp8266 (default), esp32

Supported boards

Name	Description
none	No DTR/RTS manipulation
ck	RTS controls RESET or CH_PD, DTR controls GPIO0
wifio	TXD controls GPIO0 via PNP transistor and DTR controls RESET via a capacitor
nodemcu	GPIO0 and RESET controlled using two NPN transistors as in NodeMCU devkit.

Examples

Create firmware files from the ELF output

Input: app.elf, output: app_00000.bin, app_40000.bin. Note the option for 4M flash size.

esptool -bz 4M -eo app.elf -bo app_00000.bin -bs .text -bs .data -bs .rodata -bc -ec -eo app.elf -es .irom0.text app_40000.bin -ec

Upload the firmware to the board connected to COM5 port at 115200 baud, using manual reset method.

esptool -cp COM5 -cd none -cb 115200 -ca 0x00000 -cf 00000.bin -ca 0x40000 -cf 40000.bin

or, equivalent:

esptool -cp COM5 -cf 00000.bin -ca 0x40000 -cf 40000.bin

Erase flash on a NodeMCU board

esptool -cp /dev/ttyUSB0 -cd nodemcu -ce

License

Copyright (C) 2014 Christian Klippel ck@atelier-klippel.de.

This code is licensed under GPL v2.