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USB Device Task priority under MQX?

Question asked by Bruce Drumm on Aug 19, 2015
Latest reply on Aug 21, 2015 by Bruce Drumm

When running the HID keyboard example for the freedom K22 board the "Device Task" is given a priority 13. Per AN3905, I was under the impression that these types of system tasks were given priorities 0 - 8 and that creation of user tasks with higher priority numbers would assure that system tasks would continue to execute. In usb_dev.c the task is created using USB_DEVICE_TASK_PRIORITY which is defined as 6, but then the task creation goes through the OSA layer for MQX which adds 7 (presumably to prevent conflicts with system tasks), resulting in a priority of 13. Is this what is intended?


The reason I'm asking is that I created a long running task at priority 12 and it prevented enumeration by blocking the device task. What priority do I need to set user tasks to in order to be assured that no system tasks are blocked?