kopia lustrzana https://github.com/espressif/esp-idf
55 wiersze
3.0 KiB
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55 wiersze
3.0 KiB
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**********************************
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USB Serial/JTAG Controller Console
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**********************************
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On chips with an integrated USB Serial/JTAG Controller, it is possible to use the part of this controller that implements a serial port (CDC) to implement the serial console, instead of using UART with an external USB-UART bridge chip. {IDF_TARGET_NAME} contains this controller, providing the following functions:
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* Bidirectional serial console, which can be used with :doc:`IDF Monitor <tools/idf-monitor>` or another serial monitor
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* Flashing using ``esptool.py`` and ``idf.py flash``.
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* JTAG debugging using e.g. OpenOCD, simultaneous with serial operations
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Note that, in contrast with the USB OTG peripheral found in some Espressif chips, the USB Serial/JTAG Controller is a fixed function device, implemented entirely in hardware. This means it cannot be reconfigured to perform any function other than to provide a serial channel and JTAG debugging functionality.
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Hardware Requirements
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=====================
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Connect {IDF_TARGET_NAME} to the USB port as follows:
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+------+-------------+
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| GPIO | USB |
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+======+=============+
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| 19 | D+ (green) |
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+------+-------------+
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| 18 | D- (white) |
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+------+-------------+
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| GND | GND (black) |
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+------+-------------+
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| | +5V (red) |
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+------+-------------+
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Some development boards may offer a USB connector for the USB Serial/JTAG Controller — in that case, no extra connections are required.
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Software Configuration
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======================
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USB console feature can be enabled using ``CONFIG_ESP_CONSOLE_USB_SERIAL_JTAG`` option in menuconfig tool (see :ref:`CONFIG_ESP_CONSOLE_UART`).
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Once the option is enabled, build the project as usual.
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Uploading the Application
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=========================
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The USB Serial/JTAG Controller is able to put the {IDF_TARGET_NAME} into download mode automatically. Simply flash as usual, but specify the USB Serial/JTAG Controller port on your system: ``idf.py flash -p PORT`` where ``PORT`` is the name of the proper port.
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Limitations
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===========
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There are several limitations to the USB console feature. These may or may not be significant, depending on the type of application being developed, and the development workflow.
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1. If the application accidentally reconfigures the USB peripheral pins, or disables the USB Serial/JTAG Controller, the device will disappear from the system. After fixing the issue in the application, you will need to manually put the {IDF_TARGET_NAME} into download mode by pulling low GPIO0 and resetting the chip.
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2. If the application enters light sleep (including automatic light sleep) or deep sleep mode, USB CDC device will disappear from the system.
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3. The behaviour between an actual USB-to-serial bridge chip and the USB Serial/JTAG Controller is slightly different if the ESP-IDF application does not listen for incoming bytes. An USB-to-serial bridge chip will just send the bytes to a (not listening) chip, while the USB Serial/JTAG Controller will block until the application reads the bytes. This can lead to a non-responsive looking terminal program.
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