66 lines
2.3 KiB
Markdown
66 lines
2.3 KiB
Markdown
<!--
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SPDX-FileCopyrightText: 2014 MicroPython & CircuitPython contributors (https://github.com/adafruit/circuitpython/graphs/contributors)
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SPDX-License-Identifier: MIT
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-->
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# WebUSB Serial Support
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To date, this has only been tested on one port (espressif), on one board (espressif_kaluga_1).
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## What it does
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If you have ever used CircuitPython on a platform with a graphical LCD display, you have probably
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already seen multiple "consoles" in use (although the LCD console is "output only").
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New compile-time option CIRCUITPY_USB_VENDOR enables an additional "console" that can be used in
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parallel with the original (CDC) serial console.
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Web pages that support the WebUSB standard can connect to the "vendor" interface and activate
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this WebUSB serial console at any time.
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You can type into either console, and CircuitPython output is sent to all active consoles.
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One example of a web page you can use to test drive this feature can be found at:
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https://adafruit.github.io/Adafruit_TinyUSB_Arduino/examples/webusb-serial/index.html
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## How to enable
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Update your platform's mpconfigboard.mk file to enable and disable specific types of USB interfaces.
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CIRCUITPY_USB_HID = xxx
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CIRCUITPY_USB_MIDI = xxx
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CIRCUITPY_USB_VENDOR = xxx
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On at least some of the hardware platforms, the maximum number of USB endpoints is fixed.
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For example, on the ESP32S2, you must pick only one of the above 3 interfaces to be enabled.
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Original espressif_kaluga_1 mpconfigboard.mk settings:
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CIRCUITPY_USB_HID = 1
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CIRCUITPY_USB_MIDI = 0
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CIRCUITPY_USB_VENDOR = 0
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Settings to enable WebUSB instead:
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CIRCUITPY_USB_HID = 0
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CIRCUITPY_USB_MIDI = 0
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CIRCUITPY_USB_VENDOR = 1
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Notice that to enable VENDOR on ESP32-S2, we had to give up HID. There may be platforms that can have both, or even all three.
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## Implementation Notes
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CircuitPython uses the tinyusb library.
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The tinyusb library already has support for WebUSB serial.
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The tinyusb examples already include a "WebUSB serial" example.
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Sidenote - The use of the term "vendor" instead of "WebUSB" was done to match tinyusb.
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Basically, this feature was ported into CircuitPython by pulling code snippets out of the
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tinyusb example, and putting them where they best belonged in the CircuitPython codebase.
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### TODO: This needs to be reworked for dynamic USB descriptors.
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