使用 Circuit Python 时，如何使 Raspberry Pico 不自动挂载为 USB 存储设备

Question

我在 Raspberry Pi Pico 上使用 Circuit Python 为我提供用于键盘快捷键的硬件按钮。我使用的是 Circuit Python 而不是 MicroPython，因为它有 USB_HID 库。

我不希望 Pico 在插入时自动挂载为 USB 存储设备。我只是希望它充当 HID 设备。我知道除了 code.py 之外，我还可以编写 boot.py 脚本，但我无法在网上任何地方找到要放入的内容，这会阻止它作为 USB 设备安装。有时我仍然希望它安装为 USB（当按下按钮/连接 GPIO 引脚时），所以我仍然有一种方法可以更改设备上的代码。

这可能吗？如果是这样，只有在连接了某个 GPIO 引脚时才会挂载 boot.py 文件应该是什么样子？

Answer 1

我最近遇到了一个需要做你正在寻找的同样的事情，并且在一个像样的兔子洞之后，我确定目前不能这样做。

https://github.com/adafruit/circuitpython/issues/1015

看起来该请求是几年前打开的，并且仍然列为打开状态。

我不确定在“小工具”模式下运行 pi 零是否可以完成此操作，但可能值得一看

Answer 2

CircuitPython 学习指南的这一部分对此进行了介绍：https://learn.adafruit.com/circuitpython-essentials/circuitpython-storage

Answer 3

这是一个很好的 HID 指南：

https://learn.adafruit.com/circuitpython-essentials/circuitpython-hid-keyboard-and-mouse

这是 HID 示例：

import time

import board
import digitalio
import usb_hid
from adafruit_hid.keyboard import Keyboard
from adafruit_hid.keyboard_layout_us import KeyboardLayoutUS
from adafruit_hid.keycode import Keycode

# A simple neat keyboard demo in CircuitPython

# The pins we'll use, each will have an internal pullup
keypress_pins = [board.A1, board.A2]
# Our array of key objects
key_pin_array = []
# The Keycode sent for each button, will be paired with a control key
keys_pressed = [Keycode.A, "Hello World!\n"]
control_key = Keycode.SHIFT

# The keyboard object!
time.sleep(1)  # Sleep for a bit to avoid a race condition on some systems
keyboard = Keyboard(usb_hid.devices)
keyboard_layout = KeyboardLayoutUS(keyboard)  # We're in the US :)

# Make all pin objects inputs with pullups
for pin in keypress_pins:
    key_pin = digitalio.DigitalInOut(pin)
    key_pin.direction = digitalio.Direction.INPUT
    key_pin.pull = digitalio.Pull.UP
    key_pin_array.append(key_pin)

# For most CircuitPython boards:
led = digitalio.DigitalInOut(board.D13)
# For QT Py M0:
# led = digitalio.DigitalInOut(board.SCK)
led.direction = digitalio.Direction.OUTPUT

print("Waiting for key pin...")

while True:
    # Check each pin
    for key_pin in key_pin_array:
        if not key_pin.value:  # Is it grounded?
            i = key_pin_array.index(key_pin)
            print("Pin #%d is grounded." % i)

            # Turn on the red LED
            led.value = True

            while not key_pin.value:
                pass  # Wait for it to be ungrounded!
            # "Type" the Keycode or string
            key = keys_pressed[i]  # Get the corresponding Keycode or string
            if isinstance(key, str):  # If it's a string...
                keyboard_layout.write(key)  # ...Print the string
            else:  # If it's not a string...
                keyboard.press(control_key, key)  # "Press"...
                keyboard.release_all()  # ..."Release"!

            # Turn off the red LED
            led.value = False

    time.sleep(0.01) ```

The example only prints Hello World, so it's not very useful, but it's a good base to mod. 

Answer 4

下面的代码是我使用的。粗略地说，它会检查是否有按钮连接到 Pico 的 IO 引脚之一。如果在插入电缆时按下按钮，则它会安装为 USB 驱动器。如果未按下按钮，则未安装：

import storage
import board, digitalio

import random

# If not pressed, the key will be at +V (due to the pull-up).
# https://learn.adafruit.com/customizing-usb-devices-in-circuitpython/circuitpy-midi-serial#circuitpy-mass-storage-device-3096583-4
button = digitalio.DigitalInOut(board.GP2)
button.direction = digitalio.Direction.INPUT
button.pull = digitalio.Pull.UP

# Disable devices only if button is not pressed.
if button.value:
    print(f"boot: button not pressed, disabling drive")
    storage.disable_usb_drive()

本文改编自examples on Adafruit's site