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 pyb.USB_VCP(id=0)¶
Create a new USB_VCP object. The id argument specifies which USB VCP port to use.
Methods¶
- 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
andUSB_VCP.CTS
. RTS is used to control read behaviour and CTS, to control write behaviour.
- 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.
- USB_VCP.isconnected()¶
Return
True
if USB is connected as a serial device, elseFalse
.
- USB_VCP.any()¶
Return
True
if any characters waiting, elseFalse
.
- USB_VCP.close()¶
This method does nothing. It exists so the USB_VCP object can act as a file.
- USB_VCP.read([nbytes])¶
Read at most
nbytes
from the serial device and return them as a bytes object. Ifnbytes
is not specified then the method reads all available bytes from the serial device. USB_VCPstream
implicitly works in non-blocking mode, so if no pending data available, this method will return immediately withNone
value.
- USB_VCP.readinto(buf[, maxlen])¶
Read bytes from the serial device and store them into
buf
, which should be a buffer-like object. At mostlen(buf)
bytes are read. Ifmaxlen
is given and then at mostmin(maxlen, len(buf))
bytes are read.Returns the number of bytes read and stored into
buf
orNone
if no pending data available.
- 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.
- 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.
- USB_VCP.write(buf)¶
Write the bytes from
buf
to the serial device.Returns the number of bytes written.
- 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 intodata
is returned.
- 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.
- 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¶
- USB_VCP.IRQ_RX¶
IRQ trigger values for
USB_VCP.irq()
.