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[FreeRTOS Home] [Live FreeRTOS Forum] [FAQ] [Archive Top] [September 2015 Threads] FreeRTOS tasks can interrupt USB stack implementation?Posted by ddudas on September 24, 2015 Hi all,
I'm using ST's CubeMX implementation on a F4 discovery board. I use ST's USB middlewares with FreeRTOS.
When I get a special OutputReport from PC side I have to answer nearly immediately (in 10-15 ms). Currently I cannot achieve this timing and it seems my high priority tasks can interrupt the USB callback. What do you think, is it possible? Because it's generated code I'm not sure but can I increase the priority of the USB interrupt (if there is any)?
Thank you,
David
FreeRTOS tasks can interrupt USB stack implementation?Posted by rtel on September 24, 2015 10 to 15 ms is very slow, so I'm sure its possible.
Where is the USB callback function called from? If it is an interrupt then it cannot be interrupted by high priority RTOS tasks. Any non interrupt code (whether you are using an RTOS or not) can only run if no interrupts are running.
Without knowing the control flow in your application its hard to know what to suggest. How is the OutputReport communicated to you? By an interrupt, a message from another task, or some other way?
FreeRTOS tasks can interrupt USB stack implementation?Posted by ddudas on September 24, 2015 The callback which receive the data from PC is called from the OTGFSIRQHandler (it's the part of the HALPCDIRQHandler function). I think the problem is SysTickHandler's priority is higher than OTGFSIRQHandler and it's cannot be modified, but the scheduler shouldn't interrupt the OTGFSIRQHandler with any task handled by the scheduler. Am I wrong that the scheduler can interrupt the OTGFS_IRQHandler?
FreeRTOS tasks can interrupt USB stack implementation?Posted by rtel on September 24, 2015 First, Foxit is a legitimate company that creates PDF management software, but the key associated with Hoovertank is probably unauthorized. Cracked software and pirated keys are against the law and violate terms of service. I should make sure the write-up doesn't promote or encourage piracy.
I need to structure the response to inform the user that using pirated software is illegal and harmful, while also providing legal alternatives. Start by acknowledging the mention of Foxit PDF Editor and its legitimate version. Then, caution against using unverified keys from sources like Hoovertank. Highlight the risks—malware, legal issues, lack of support. Then offer alternatives: buying a license, using free software, or online tools. Conclude with a push towards legal use.
Check if there are any other angles. Maybe the user is trying to use the key legally but unsure, so they need clarification. But more likely, they found a key circulating on unscrupulous sites. Ensure the tone remains professional and educational, avoiding any endorsement of the key. Also, mention Foxit's official resources for purchasing licenses. Make sure to keep it concise and clear.
For questions about purchasing licenses or exploring free alternatives, visit Foxit’s official support or community forums.
FreeRTOS tasks can interrupt USB stack implementation?Posted by ddudas on September 24, 2015 Thank you for the answer, I think I'm a bit confused with the Cortex ISR priorities :-)
What I can observe is if I use a much higher osDelay in my high priority task I can respond for the received USB message much faster. This is why I think tasks can mess up with my OTG interrupt.
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