Previous to this patch the USB CDC driver used TIM3 to trigger the
sending of outgoing data over USB serial. This patch changes the
behaviour so that the USB SOF interrupt is used to trigger the processing
of the sending. This reduces latency and increases bandwidth of outgoing
data.
Thanks to Martin Fischer, aka @hoihu, for the idea and initial prototype.
See PR #1713.
This patch also enables non-blocking streams on stmhal port.
One can now make a USB-UART pass-through function:
def pass_through(usb, uart):
while True:
select.select([usb, uart], [], [])
if usb.any():
uart.write(usb.read(256))
if uart.any():
usb.write(uart.read(256))
pass_through(pyb.USB_VCP(), pyb.UART(1, 9600))
Before, pyb.stdin/pyb.stdout allowed some kind of access to the USB VCP
device, but it was basic access.
This patch adds a proper USB_VCP class and object with much more control
over the USB VCP device. Create an object with pyb.USB_VCP(), then use
this object as if it were a UART object. It has send, recv, read,
write, and other methods. send and recv allow a timeout to be specified.
Addresses issue 774.
Blanket wide to all .c and .h files. Some files originating from ST are
difficult to deal with (license wise) so it was left out of those.
Also merged modpyb.h, modos.h, modstm.h and modtime.h in stmhal/.
New USB HAL is quite a bit improved over previous one. Now has better
callbacks and flow control.
REPL over USB CDC now works as before, except for soft-reset (since USB
driver uses malloc...).
Damien George