boards/xtensa/esp32/doc/index.rst - third_party/github/zephyrproject-rtos/zephyr - Git at Google

 .. _esp32:

 ESP32
 #####

 Overview
 ********


 ESP32 is a series of low cost, low power system on a chip microcontrollers
 with integrated Wi-Fi & dual-mode Bluetooth.  The ESP32 series employs a
 Tensilica Xtensa LX6 microprocessor in both dual-core and single-core
 variations.  ESP32 is created and developed by Espressif Systems, a
 Shanghai-based Chinese company, and is manufactured by TSMC using their 40nm
 process. [1]_

 The features include the following:

 - Dual core Xtensa microprocessor (LX6), running at 160 or 240MHz
 - 520KB of SRAM
 - 802.11b/g/n/e/i
 - Bluetooth v4.2 BR/EDR and BLE
 - Various peripherals:

   - 12-bit ADC with up to 18 channels
   - 2x 8-bit DACs
   - 10x touch sensors
   - Temperature sensor
   - 4x SPI
   - 2x I2S
   - 2x I2C
   - 3x UART
   - SD/SDIO/MMC host
   - Slave (SDIO/SPI)
   - Ethernet MAC
   - CAN bus 2.0
   - IR (RX/TX)
   - Motor PWM
   - LED PWM with up to 16 channels
   - Hall effect sensor

 - Cryptographic hardware acceleration (RNG, ECC, RSA, SHA-2, AES)
 - 5uA deep sleep current

 System requirements
 *******************

 Prerequisites
 =============

 Two components are required in order to build this port: the `toolchain`_
 and the `SDK`_.  Both are provided by the SoC manufacturer.

 The SDK contains headers and a hardware abstraction layer library
 (provided only as object files) that are required for the port to
 function.

 The toolchain is available for Linux, Windows, and Mac hosts and
 instructions to obtain and set them up are available in the ESP-IDF
 repository, using the toolchain and SDK links above.

 Set up build environment
 ========================

 With both the toolchain and SDK installed, the Zephyr build system must be
 instructed to use this particular variant by setting the
 ``ZEPHYR_TOOLCHAIN_VARIANT`` shell variable.  Two other environment variables
 should also be set, pointing to, respectively, the path where ESP-IDF can be
 located, and where the toolchain has been installed:

 .. code-block:: console

    export ZEPHYR_TOOLCHAIN_VARIANT="espressif"
    export ESP_IDF_PATH="/path/to/esp-idf"
    export ESPRESSIF_TOOLCHAIN_PATH="/path/to/xtensa-esp32-elf/"

 Since ESP-IDF is an external project in constant development, it's possible
 that files that Zephyr depends on will be moved, removed, or renamed.  Those
 files are mostly header files containing hardware definitions, which are
 unlikely to change and require fixes from the vendor.  In addition to
 setting the environment variables above, also check out an earlier version
 of ESP-IDF:

 .. code-block:: console

    cd ${ESP_IDF_PATH}
    git checkout b2ff235bd00

 Flashing
 ========

 The usual ``flash`` target will work with the ``esp32`` board
 configuration. Here is an example for the :ref:`hello_world`
 application.

 .. zephyr-app-commands::
    :zephyr-app: samples/hello_world
    :board: esp32
    :goals: flash

 Refer to :ref:`build_an_application` and :ref:`application_run` for
 more details.

 It's impossible to determine which serial port the ESP32 board is
 connected to, as it uses a generic RS232-USB converter.  The default of
 ``/dev/ttyUSB0`` is provided as that's often the assigned name on a Linux
 machine without any other such converters.

 The baud rate of 921600bps is recommended.  If experiencing issues when
 flashing, try halving the value a few times (460800, 230400, 115200,
 etc).  It might be necessary to change the flash frequency or the flash
 mode; please refer to the `esptool documentation`_ for guidance on these
 settings.

 All flashing options are now handled by the :ref:`west` tool, including flashing
 with custom options such as a different serial port.  The ``west`` tool supports
 specific options for the ESP32 board, as listed here:

   --esp-idf-path ESP_IDF_PATH
                         path to ESP-IDF
   --esp-device ESP_DEVICE
                         serial port to flash, default /dev/ttyUSB0
   --esp-baud-rate ESP_BAUD_RATE
                         serial baud rate, default 921600
   --esp-flash-size ESP_FLASH_SIZE
                         flash size, default "detect"
   --esp-flash-freq ESP_FLASH_FREQ
                         flash frequency, default "40m"
   --esp-flash-mode ESP_FLASH_MODE
                         flash mode, default "dio"
   --esp-tool ESP_TOOL   if given, complete path to espidf. default is to
                         search for it in [ESP_IDF_PATH]/components/esptool_py/
                         esptool/esptool.py
   --esp-flash-bootloader ESP_FLASH_BOOTLOADER
                         Bootloader image to flash
   --esp-flash-partition_table ESP_FLASH_PARTITION_TABLE
                         Partition table to flash

 For example, to flash to ``/dev/ttyUSB2``, use the following command after
 having build the application in the ``build`` directory:


 .. code-block:: console

    west flash -d build/ --skip-rebuild --esp-device /dev/ttyUSB2

 Using JTAG
 ==========

 As with much custom hardware, the ESP-32 modules require patches to
 OpenOCD that are not upstream.  Espressif maintains their own fork of
 the project here.  By convention they put it in ``~/esp`` next to the
 installations of their toolchain and SDK:

 .. code-block:: console

    cd ~/esp

    git clone https://github.com/espressif/openocd-esp32

    cd openocd-esp32
    ./bootstrap
    ./configure
    make

 On the ESP-WROVER-KIT board, the JTAG pins are connected internally to
 a USB serial port on the same device as the console.  These boards
 require no external hardware and are debuggable as-is.  The JTAG
 signals, however, must be jumpered closed to connect the internal
 controller (the default is to leave them disconnected).  The jumper
 headers are on the right side of the board as viewed from the power
 switch, next to similar headers for SPI and UART.  See
 `ESP-WROVER-32 V3 Getting Started Guide`_ for details.

 On the ESP-WROOM-32 DevKitC board, the JTAG pins are not run to a
 standard connector (e.g. ARM 20-pin) and need to be manually connected
 to the external programmer (e.g. a Flyswatter2):

 +------------+-----------+
 | ESP32 pin  | JTAG pin  |
 +============+===========+
 | 3V3        | VTRef     |
 +------------+-----------+
 | EN         | nTRST     |
 +------------+-----------+
 | IO14       | TMS       |
 +------------+-----------+
 | IO12       | TDI       |
 +------------+-----------+
 | GND        | GND       |
 +------------+-----------+
 | IO13       | TCK       |
 +------------+-----------+
 | IO15       | TDO       |
 +------------+-----------+

 Once the device is connected, you should be able to connect with (for
 a DevKitC board, replace with esp32-wrover.cfg for WROVER):

 .. code-block:: console

     cd ~/esp/openocd-esp32
     src/openocd -f interface/ftdi/flyswatter2.cfg -c 'set ESP32_ONLYCPU 1' -c 'set ESP32_RTOS none' -f board/esp-wroom-32.cfg -s tcl

 The ESP32_ONLYCPU setting is critical: without it OpenOCD will present
 only the "APP_CPU" via the gdbserver, and not the "PRO_CPU" on which
 Zephyr is running.  It's currently unexplored as to whether the CPU
 can be switched at runtime or if breakpoints can be set for
 either/both.

 Now you can connect to openocd with gdb and point it to the OpenOCD
 gdbserver running (by default) on localhost port 3333.  Note that you
 must use the gdb distributed with the ESP-32 SDK.  Builds off of the
 FSF mainline get inexplicable protocol errors when connecting.

 .. code-block:: console

     ~/esp/xtensa-esp32-elf/bin/xtensa-esp32-elf-gdb outdir/esp32/zephyr.elf
     (gdb) target remote localhost:3333

 Further documentation can be obtained from the SoC vendor in `JTAG debugging
 for ESP32`_.

 References
 **********

 .. [1] https://en.wikipedia.org/wiki/ESP32
 .. _`ESP32 Technical Reference Manual`: https://espressif.com/sites/default/files/documentation/esp32_technical_reference_manual_en.pdf
 .. _`JTAG debugging for ESP32`: http://esp-idf.readthedocs.io/en/latest/api-guides/jtag-debugging/index.html
 .. _`toolchain`: https://esp-idf.readthedocs.io/en/latest/get-started/index.html#get-started-setup-toochain
 .. _`SDK`: https://esp-idf.readthedocs.io/en/latest/get-started/index.html#get-started-get-esp-idf
 .. _`Hardware Referecne`: https://esp-idf.readthedocs.io/en/latest/hw-reference/index.html
 .. _`esptool documentation`: https://github.com/espressif/esptool/blob/master/README.md
 .. _`esptool.py`: https://github.com/espressif/esptool
 .. _`ESP-WROVER-32 V3 Getting Started Guide`: https://dl.espressif.com/doc/esp-idf/latest/get-started/get-started-wrover-kit.html
	.. _esp32:

	ESP32
	#####

	Overview
	********


	ESP32 is a series of low cost, low power system on a chip microcontrollers
	with integrated Wi-Fi & dual-mode Bluetooth. The ESP32 series employs a
	Tensilica Xtensa LX6 microprocessor in both dual-core and single-core
	variations. ESP32 is created and developed by Espressif Systems, a
	Shanghai-based Chinese company, and is manufactured by TSMC using their 40nm
	process. [1]_

	The features include the following:

	- Dual core Xtensa microprocessor (LX6), running at 160 or 240MHz
	- 520KB of SRAM
	- 802.11b/g/n/e/i
	- Bluetooth v4.2 BR/EDR and BLE
	- Various peripherals:

	- 12-bit ADC with up to 18 channels
	- 2x 8-bit DACs
	- 10x touch sensors
	- Temperature sensor
	- 4x SPI
	- 2x I2S
	- 2x I2C
	- 3x UART
	- SD/SDIO/MMC host
	- Slave (SDIO/SPI)
	- Ethernet MAC
	- CAN bus 2.0
	- IR (RX/TX)
	- Motor PWM
	- LED PWM with up to 16 channels
	- Hall effect sensor

	- Cryptographic hardware acceleration (RNG, ECC, RSA, SHA-2, AES)
	- 5uA deep sleep current

	System requirements
	*******************

	Prerequisites
	=============

	Two components are required in order to build this port: the `toolchain`_
	and the `SDK`_. Both are provided by the SoC manufacturer.

	The SDK contains headers and a hardware abstraction layer library
	(provided only as object files) that are required for the port to
	function.

	The toolchain is available for Linux, Windows, and Mac hosts and
	instructions to obtain and set them up are available in the ESP-IDF
	repository, using the toolchain and SDK links above.

	Set up build environment
	========================

	With both the toolchain and SDK installed, the Zephyr build system must be
	instructed to use this particular variant by setting the
	``ZEPHYR_TOOLCHAIN_VARIANT`` shell variable. Two other environment variables
	should also be set, pointing to, respectively, the path where ESP-IDF can be
	located, and where the toolchain has been installed:

	.. code-block:: console

	export ZEPHYR_TOOLCHAIN_VARIANT="espressif"
	export ESP_IDF_PATH="/path/to/esp-idf"
	export ESPRESSIF_TOOLCHAIN_PATH="/path/to/xtensa-esp32-elf/"

	Since ESP-IDF is an external project in constant development, it's possible
	that files that Zephyr depends on will be moved, removed, or renamed. Those
	files are mostly header files containing hardware definitions, which are
	unlikely to change and require fixes from the vendor. In addition to
	setting the environment variables above, also check out an earlier version
	of ESP-IDF:

	.. code-block:: console

	cd ${ESP_IDF_PATH}
	git checkout b2ff235bd00

	Flashing
	========

	The usual ``flash`` target will work with the ``esp32`` board
	configuration. Here is an example for the :ref:`hello_world`
	application.

	.. zephyr-app-commands::
	:zephyr-app: samples/hello_world
	:board: esp32
	:goals: flash

	Refer to :ref:`build_an_application` and :ref:`application_run` for
	more details.

	It's impossible to determine which serial port the ESP32 board is
	connected to, as it uses a generic RS232-USB converter. The default of
	``/dev/ttyUSB0`` is provided as that's often the assigned name on a Linux
	machine without any other such converters.

	The baud rate of 921600bps is recommended. If experiencing issues when
	flashing, try halving the value a few times (460800, 230400, 115200,
	etc). It might be necessary to change the flash frequency or the flash
	mode; please refer to the `esptool documentation`_ for guidance on these
	settings.

	All flashing options are now handled by the :ref:`west` tool, including flashing
	with custom options such as a different serial port. The ``west`` tool supports
	specific options for the ESP32 board, as listed here:

	--esp-idf-path ESP_IDF_PATH
	path to ESP-IDF
	--esp-device ESP_DEVICE
	serial port to flash, default /dev/ttyUSB0
	--esp-baud-rate ESP_BAUD_RATE
	serial baud rate, default 921600
	--esp-flash-size ESP_FLASH_SIZE
	flash size, default "detect"
	--esp-flash-freq ESP_FLASH_FREQ
	flash frequency, default "40m"
	--esp-flash-mode ESP_FLASH_MODE
	flash mode, default "dio"
	--esp-tool ESP_TOOL if given, complete path to espidf. default is to
	search for it in [ESP_IDF_PATH]/components/esptool_py/
	esptool/esptool.py
	--esp-flash-bootloader ESP_FLASH_BOOTLOADER
	Bootloader image to flash
	--esp-flash-partition_table ESP_FLASH_PARTITION_TABLE
	Partition table to flash

	For example, to flash to ``/dev/ttyUSB2``, use the following command after
	having build the application in the ``build`` directory:


	.. code-block:: console

	west flash -d build/ --skip-rebuild --esp-device /dev/ttyUSB2

	Using JTAG
	==========

	As with much custom hardware, the ESP-32 modules require patches to
	OpenOCD that are not upstream. Espressif maintains their own fork of
	the project here. By convention they put it in ``~/esp`` next to the
	installations of their toolchain and SDK:

	.. code-block:: console

	cd ~/esp

	git clone https://github.com/espressif/openocd-esp32

	cd openocd-esp32
	./bootstrap
	./configure
	make

	On the ESP-WROVER-KIT board, the JTAG pins are connected internally to
	a USB serial port on the same device as the console. These boards
	require no external hardware and are debuggable as-is. The JTAG
	signals, however, must be jumpered closed to connect the internal
	controller (the default is to leave them disconnected). The jumper
	headers are on the right side of the board as viewed from the power
	switch, next to similar headers for SPI and UART. See
	`ESP-WROVER-32 V3 Getting Started Guide`_ for details.

	On the ESP-WROOM-32 DevKitC board, the JTAG pins are not run to a
	standard connector (e.g. ARM 20-pin) and need to be manually connected
	to the external programmer (e.g. a Flyswatter2):

	+------------+-----------+
	\| ESP32 pin \| JTAG pin \|
	+============+===========+
	\| 3V3 \| VTRef \|
	+------------+-----------+
	\| EN \| nTRST \|
	+------------+-----------+
	\| IO14 \| TMS \|
	+------------+-----------+
	\| IO12 \| TDI \|
	+------------+-----------+
	\| GND \| GND \|
	+------------+-----------+
	\| IO13 \| TCK \|
	+------------+-----------+
	\| IO15 \| TDO \|
	+------------+-----------+

	Once the device is connected, you should be able to connect with (for
	a DevKitC board, replace with esp32-wrover.cfg for WROVER):

	.. code-block:: console

	cd ~/esp/openocd-esp32
	src/openocd -f interface/ftdi/flyswatter2.cfg -c 'set ESP32_ONLYCPU 1' -c 'set ESP32_RTOS none' -f board/esp-wroom-32.cfg -s tcl

	The ESP32_ONLYCPU setting is critical: without it OpenOCD will present
	only the "APP_CPU" via the gdbserver, and not the "PRO_CPU" on which
	Zephyr is running. It's currently unexplored as to whether the CPU
	can be switched at runtime or if breakpoints can be set for
	either/both.

	Now you can connect to openocd with gdb and point it to the OpenOCD
	gdbserver running (by default) on localhost port 3333. Note that you
	must use the gdb distributed with the ESP-32 SDK. Builds off of the
	FSF mainline get inexplicable protocol errors when connecting.

	.. code-block:: console

	~/esp/xtensa-esp32-elf/bin/xtensa-esp32-elf-gdb outdir/esp32/zephyr.elf
	(gdb) target remote localhost:3333

	Further documentation can be obtained from the SoC vendor in `JTAG debugging
	for ESP32`_.

	References
	**********

	.. [1] https://en.wikipedia.org/wiki/ESP32
	.. _`ESP32 Technical Reference Manual`: https://espressif.com/sites/default/files/documentation/esp32_technical_reference_manual_en.pdf
	.. _`JTAG debugging for ESP32`: http://esp-idf.readthedocs.io/en/latest/api-guides/jtag-debugging/index.html
	.. _`toolchain`: https://esp-idf.readthedocs.io/en/latest/get-started/index.html#get-started-setup-toochain
	.. _`SDK`: https://esp-idf.readthedocs.io/en/latest/get-started/index.html#get-started-get-esp-idf
	.. _`Hardware Referecne`: https://esp-idf.readthedocs.io/en/latest/hw-reference/index.html
	.. _`esptool documentation`: https://github.com/espressif/esptool/blob/master/README.md
	.. _`esptool.py`: https://github.com/espressif/esptool
	.. _`ESP-WROVER-32 V3 Getting Started Guide`: https://dl.espressif.com/doc/esp-idf/latest/get-started/get-started-wrover-kit.html