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.. currentmodule:: pyb
.. _pyb.USB_VCP:
class USB_VCP -- USB virtual comm port
======================================
The USB_VCP class allows creation of a `stream`-like object representing the USB
virtual comm port. It can be used to read and write data over USB to
the connected host.
Constructors
------------
.. class:: USB_VCP(id=0)
Create a new USB_VCP object. The *id* argument specifies which USB VCP port to
use.
Methods
-------
.. method:: USB_VCP.init(*, flow=-1)
Configure the USB VCP port. If the *flow* argument is not -1 then the value sets
the flow control, which can be a bitwise-or of ``USB_VCP.RTS`` and ``USB_VCP.CTS``.
RTS is used to control read behaviour and CTS, to control write behaviour.
.. method:: USB_VCP.setinterrupt(chr)
Set the character which interrupts running Python code. This is set
to 3 (CTRL-C) by default, and when a CTRL-C character is received over
the USB VCP port, a KeyboardInterrupt exception is raised.
Set to -1 to disable this interrupt feature. This is useful when you
want to send raw bytes over the USB VCP port.
.. method:: USB_VCP.isconnected()
Return ``True`` if USB is connected as a serial device, else ``False``.
.. method:: USB_VCP.any()
Return ``True`` if any characters waiting, else ``False``.
.. method:: USB_VCP.close()
This method does nothing. It exists so the USB_VCP object can act as
a file.
.. method:: USB_VCP.read([nbytes])
Read at most ``nbytes`` from the serial device and return them as a
bytes object. If ``nbytes`` is not specified then the method reads
all available bytes from the serial device.
USB_VCP `stream` implicitly works in non-blocking mode,
so if no pending data available, this method will return immediately
with ``None`` value.
.. method:: USB_VCP.readinto(buf, [maxlen])
Read bytes from the serial device and store them into ``buf``, which
should be a buffer-like object. At most ``len(buf)`` bytes are read.
If ``maxlen`` is given and then at most ``min(maxlen, len(buf))`` bytes
are read.
Returns the number of bytes read and stored into ``buf`` or ``None``
if no pending data available.
.. method:: USB_VCP.readline()
Read a whole line from the serial device.
Returns a bytes object containing the data, including the trailing
newline character or ``None`` if no pending data available.
.. method:: USB_VCP.readlines()
Read as much data as possible from the serial device, breaking it into
lines.
Returns a list of bytes objects, each object being one of the lines.
Each line will include the newline character.
.. method:: USB_VCP.write(buf)
Write the bytes from ``buf`` to the serial device.
Returns the number of bytes written.
.. method:: USB_VCP.recv(data, *, timeout=5000)
Receive data on the bus:
- ``data`` can be an integer, which is the number of bytes to receive,
or a mutable buffer, which will be filled with received bytes.
- ``timeout`` is the timeout in milliseconds to wait for the receive.
Return value: if ``data`` is an integer then a new buffer of the bytes received,
otherwise the number of bytes read into ``data`` is returned.
.. method:: USB_VCP.send(data, *, timeout=5000)
Send data over the USB VCP:
- ``data`` is the data to send (an integer to send, or a buffer object).
- ``timeout`` is the timeout in milliseconds to wait for the send.
Return value: number of bytes sent.
.. method:: USB_VCP.irq(handler=None, trigger=IRQ_RX, hard=False)
Register *handler* to be called whenever an event specified by *trigger*
occurs. The *handler* function must take exactly one argument, which will
be the USB VCP object. Pass in ``None`` to disable the callback.
Valid values for *trigger* are:
- ``USB_VCP.IRQ_RX``: new data is available for reading from the USB VCP object.
Constants
---------
.. data:: USB_VCP.RTS
USB_VCP.CTS
to select the flow control type.
.. data:: USB_VCP.IRQ_RX
IRQ trigger values for :meth:`USB_VCP.irq`.
|
