The Qin Empire Speak Khmer -

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

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?

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?

This theory remains unproven and is rejected by most historical linguists due to a lack of regular sound correspondences. Perhaps the most plausible explanation is a simple phonetic mistake. The Chinese character for Qin (秦) is pronounced Qín in Mandarin. However, in some southern Chinese languages (e.g., Cantonese, Hakka, or ancient Chu dialects), the pronunciation might have been closer to Zeon or Chin .

If you want to explore a real historical connection between China and the Khmer, look to the Tang and Song dynasties (618–1279 CE), when Chinese envoys and traders first documented the kingdom of "Chenla" and "Funan" — the precursors to Angkor. Or study the 13th-century Chinese diplomat Zhou Daguan, who lived in Angkor and wrote The Customs of Cambodia .

The Khmer Empire (802–1431 CE), centered in present-day Cambodia, is famous for Angkor Wat, sophisticated irrigation systems, and a completely different linguistic family: Austroasiatic.

Some fringe historians have suggested that the Qin were not ethnically Han but were themselves a "mixed" group who absorbed a southern substrate language. They point to the fact that the Qin homeland was closer to the non-Sinitic Qiang and Di tribes. This is speculative at best. In the mid-20th century, linguist Paul K. Benedict proposed an Austro-Tai macro-family that later included Miao-Yao and, controversially, linked Sino-Tibetan with Austroasiatic into a superphylum called Sino-Austronesian or Sino-Austroasiatic .

During the Qin dynasty, their southern expansion stopped roughly at the Red River Delta (modern northern Vietnam). At that time, the region was inhabited by Proto-Vietic and early Mon-Khmer groups, but the great Khmer Empire would not arise for another 1,000 years.

However, after the Qin fell in 206 BCE, a Qin general named Zhao Tuo established the kingdom of (Nam Việt) in modern Guangdong and northern Vietnam. Nanyue ruled over a mixed Sinitic-Austroasiatic population for nearly a century before being absorbed by the Han dynasty in 111 BCE.

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.