class USB_VCP – USB virtual comm port
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
pyb.USB_VCP
class pyb.USB_VCP(id=0)Create a new USB_VCP object. The id argument specifies which USB VCP port to use.
Create a new USB_VCP object.
Methods
USB_VCP.init
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.
USB_VCP.setinterrupt
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
USB_VCP.isconnected()Return True if USB is connected as a serial device, else False.
USB_VCP.debug_mode_enabled
USB_VCP.debug_mode_enabled()Return True if OpenMV IDE is connected to the OpenMV Cam.
USB_VCP.any
USB_VCP.any()Return True if any characters waiting, else False.
USB_VCP.close
USB_VCP.close()This method does nothing. It exists so the USB_VCP object can act as a file.
USB_VCP.read
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.
USB_VCP.readinto
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.
USB_VCP.readline
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
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
USB_VCP.write(buf)Write the bytes from buf to the serial device.
Returns the number of bytes written.
USB_VCP.recv
USB_VCP.recv(data, *, timeout=5000)Receive data on the bus:
datacan be an integer, which is the number of bytes to receive, or a mutable buffer, which will be filled with received bytes.timeoutis 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.
USB_VCP.send
USB_VCP.send(data, *, timeout=5000)Send data over the USB VCP:
datais the data to send (an integer to send, or a buffer object).timeoutis the timeout in milliseconds to wait for the send.
Return value: number of bytes sent.
USB_VCP.irq
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.RTS
USB_VCP.RTSUSB_VCP.CTS
USB_VCP.CTSto select the flow control type.
USB_VCP.IRQ_RX
USB_VCP.IRQ_RXIRQ trigger values for USB_VCP.irq().