The previous version did not work on MCUs that only had USB device mode
(compared to OTG) because of the handling of NAK. And this previous
handling of NAK had a race condition where a new packet could come in
before USBD_HID_SetNAK was called (since USBD_HID_ReceivePacket clears NAK
as part of its operation). Furthermore, the double buffering of incoming
reports was not working, only one buffer could be used at a time.
This commit rewrites the HID interface code to have a single incoming
buffer, and only calls USBD_HID_ReceivePacket after the user has read the
incoming report (similar to how the VCP does its flow control). As such,
USBD_HID_SetNAK and USBD_HID_ClearNAK are no longer needed.
API functionality from the user's point of view should be unchanged with
this commit.
The new configurations MICROPY_HW_USB_MSC and MICROPY_HW_USB_HID can be
used by a board to enabled or disable MSC and/or HID. They are both
enabled by default.
Eventually these responses could be filled in by a function to make their
contents dynamic, depending on the attached logical units. But for now
they are fixed, and this patch fixes the MODE SENSE(6) responses so it is
the correct length with the correct header.
The board config option MICROPY_HW_USB_ENABLE_CDC2 is now changed to
MICROPY_HW_USB_CDC_NUM, and the latter should be defined to the maximum
number of CDC interfaces to support (defaults to 1).
The new compile-time option is MICROPY_HW_USB_MAX_POWER_MA. Set this in
the board configuration file to the maximum current in mA that the board
will draw over USB. The default is 500mA.
The new compile-time option is MICROPY_HW_USB_SELF_POWERED. Set this
option to 1 in the board configuration file to indicate that the USB device
is self powered. This option is disabled by default (previous behaviour).
Prior to this commit the USB CDC used the USB start-of-frame (SOF) IRQ to
regularly check if buffered data needed to be sent out to the USB host.
This wasted resources (CPU, power) if no data needed to be sent.
This commit changes how the USB CDC transmits buffered data:
- When new data is first available to send the data is queued immediately
on the USB IN endpoint, ready to be sent as soon as possible.
- Subsequent additions to the buffer (via usbd_cdc_try_tx()) will wait.
- When the low-level USB driver has finished sending out the data queued
in the USB IN endpoint it calls usbd_cdc_tx_ready() which immediately
queues any outstanding data, waiting for the next IN frame.
The benefits on this new approach are:
- SOF IRQ does not need to run continuously so device has a better chance
to sleep for longer, and be more responsive to other IRQs.
- Because SOF IRQ is off, current consumption is reduced by a small amount,
roughly 200uA when USB is connected (measured on PYBv1.0).
- CDC tx throughput (USB IN) on PYBv1.0 is about 2.3 faster (USB OUT is
unchanged).
- When USB is connected, Python code that is executing is slightly faster
because SOF IRQ no longer interrupts continuously.
- On F733 with USB HS, CDC tx throughput is about the same as prior to this
commit.
- On F733 with USB HS, Python code is about 5% faster because of no SOF.
As part of this refactor, the serial port should no longer echo initial
characters when the serial port is first opened (this only used to happen
rarely on USB FS, but on USB HS is was more evident).
These files provide no additional information, all the version and license
information is captured in the relevant files in these subdirectories.
Thanks to @JoeSc for the original patch.
This patch adds the configuration MICROPY_HW_USB_ENABLE_CDC2 which enables
a new USB device configuration at runtime: VCP+VCP+MSC. It will give two
independent VCP interfaces available via pyb.USB_VCP(0) and pyb.USB_VCP(1).
The first one is the usual one and has the REPL on it. The second one is
available for general use.
This configuration is disabled by default because if the mode is not used
then it takes up about 2200 bytes of RAM. Also, F4 MCUs can't support this
mode on their USB FS peripheral (eg PYBv1.x) because they don't have enough
endpoints. The USB HS peripheral of an F4 supports it, as well as both the
USB FS and USB HS peripherals of F7 MCUs.
Martin Fischer
Damien George
Andrew Leech