.. _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 ------------- Espressif HAL requires WiFi and Bluetooth binary blobs in order work. Run the command below to retrieve those files. .. code-block:: console west blobs fetch hal_espressif .. note:: It is recommended running the command above after :file:`west update`. Building & Flashing ------------------- Build and flash applications as usual (see :ref:`build_an_application` and :ref:`application_run` for more details). .. zephyr-app-commands:: :zephyr-app: samples/hello_world :board: esp32 :goals: build 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 Open the serial monitor using the following command: .. code-block:: shell west espressif monitor After the board has automatically reset and booted, you should see the following message in the monitor: .. code-block:: console ***** Booting Zephyr OS vx.x.x-xxx-gxxxxxxxxxxxx ***** Hello World! esp32 Debugging --------- As with much custom hardware, the ESP32 modules require patches to OpenOCD that are not upstreamed yet. Espressif maintains their own fork of the project. The custom OpenOCD can be obtained at `OpenOCD ESP32`_ The Zephyr SDK uses a bundled version of OpenOCD by default. You can overwrite that behavior by adding the ``-DOPENOCD= -DOPENOCD_DEFAULT_PATH=`` parameter when building. Here is an example for building the :ref:`hello_world` application. .. zephyr-app-commands:: :zephyr-app: samples/hello_world :board: esp32 :goals: build flash :gen-args: -DOPENOCD= -DOPENOCD_DEFAULT_PATH= You can debug an application in the usual way. Here is an example for the :ref:`hello_world` application. .. zephyr-app-commands:: :zephyr-app: samples/hello_world :board: esp32 :goals: debug Using JTAG ====================== 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`_. Note on Debugging with GDB Stub =============================== GDB stub is enabled on ESP32. * When adding breakpoints, please use hardware breakpoints with command ``hbreak``. Command ``break`` uses software breakpoints which requires modifying memory content to insert break/trap instructions. This does not work as the code is on flash which cannot be randomly accessed for modification. 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`: https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-guides/jtag-debugging/index.html .. _`Hardware Reference`: https://docs.espressif.com/projects/esp-idf/en/latest/esp32/hw-reference/index.html .. _`ESP-WROVER-32 V3 Getting Started Guide`: https://docs.espressif.com/projects/esp-idf/en/latest/esp32/hw-reference/esp32/get-started-wrover-kit.html .. _`OpenOCD ESP32`: https://github.com/espressif/openocd-esp32/releases