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USB stack device task option

Question asked by SCOTT MILLER on Mar 23, 2019
Latest reply on Mar 28, 2019 by Daniel Chen

I'm working on porting a project from the old Freescale bare metal USB stack v5 to the current SDK version mostly for the sake of improving compatibility with FreeRTOS (the v5 stack never had the OS support finished) and I've got it running, but I can't find the information I'm looking for on how it interacts with an RTOS.


I'm mostly interested in USB_DEVICE_CONFIG_USE_TASK.  Based on what I remember of the v4 stack and what I can see in the code, I think the option sets it up to use a queue so that the USB ISR just passes messages to a dedicated task.  Is this documented somewhere?


One of the things I'm looking for is the required stack size.  The example is set to 5000 bytes.  How much is required by the stack itself?  And I'm assuming that the application callbacks are made from this task.  Is that right?


I've skimmed through all of the USB stack user's guide, device reference manual, and composite device reference manual, and searched all over for details on the task setup, and I'm just not finding anything.  I've been at it for 12 hours today and I'm running out of steam.  If someone could point me in the direction of the appropriate documentation, I'd really appreciate it.  Or if it doesn't exist yet, that'd be good to know too and I can dive in to the source code and figure it out when I'm not so tired - I just can't take any more searching for documentation that might not exist tonight.