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嗨,阿南德!
我知道为什么我的转会这么慢。这是轮询间隔,而从FIFO没有一个完整的数据包。 在我的例子中,我使用了14MHz的中断传输模式,ARM时钟数据到从FIFO,但是USB速度太快,当USB读取所有可用的数据时,ARM没有写完整的数据包,所以在某个时间没有读取数据,然后主机将等待至少1ms再次读取,但是在初始化期间。RVAR数据溢出。 因此USB的实际工作时间很小,传输速度也很慢。 另一个问题:什么是轮询等时转移?那么散货船呢? 以上来自于百度翻译 以下为原文 Hi,Anand! I know why my transfer is so slow. It's the polling interval while slave fifo doesn't have a complet packet. In my case,I used interrupt transfer mode,ARM clocks datum into slave fifo in 14Mhz,but the USB is so fast that ARM hasn't write a complete packet when USB read out all available datum,so in some time there is no data for reading, then host would wait at least 1ms to read again, but during the interval data overflowed. So the real working time of USB is small, the transfer is in slow speed also. Another question: what is the polling intrval of isochronous transfer? and how about the bulk trransfer? |
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等时和中断端点保证了带宽。基于描述符,每个微框架可以有主机请求3个包,即每125US 3个包。块没有保证带宽,如果总线空闲,可以提供比ISO和中断大得多的带宽,但是如果总线不空闲,那么您可能会看到带宽下降。当你说溢出时,你是否在GPIF/从FIFO接口上实现流量控制(检查满标志、空标志等)?
当做, 阿南德 以上来自于百度翻译 以下为原文 Isochronous and interrupt endpoint have guaranteed bandwidth. Based on the descriptor you can have the host request 3 packets per microframe i.e. 3 packets per 125us. Bulk does not have guaranteed bandwidth, if the bus is free bulk can provide significantly higher bandwidth than iso and interrupt but if the bus is not free then you might see drop in bandwidth. When you say overflow, are you implementing flow control (check full flag, empty flag etc) on the GPIF/Slave FIFO interface or not? Regards, Anand |
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1,当从FIFO中没有可用的分组时,主机将等待至少1ms重读从FIFO。主机在等时性传输和批量传输中等待多长时间(总线是免费的)?
2、你说“基于描述符可以有主机请求3包每微帧”,是你提到的端点描述符的描述符?它是最大的包大小吗?(即最大包大小= 0x1400,有3packets,最大包大小= 0x0400,还有一包)。这是对的吗? 3,我注意到cyapi.chm的setxfersize,怎么会改变的setxfersize影响USB总线?我仍然不理解StxFelSekes的内涵。 谢谢您!阿南德。 以上来自于百度翻译 以下为原文 1,when there is no available packet in slave fifo,host would wait at least 1ms to reread the slave fifo. How much time would the host wait in isochrounous transfer and bulk transfer(bus is free)? 2,You say "Based on the descriptor you can have the host request 3 packets per microframe", Is the descriptor you mentioned the endpoint descriptor? Is it the Maximun packet size?(i.e. Maximun packet size=0x1400, there is 3packets, Maximun packet size=0x0400,there is one packets). Is this right? 3,I noticed the setxfersize in cyapi.chm, How would the change to the setxfersize affect the USB bus? I still don't understand the connotation of setxfersize . Thank you! Anand. |
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2。是的。仅描述符。
1。这取决于主机调度。假设您配置描述符,每个微框架上为ISO说3个包,主机将在微框架内请求3个包,但实际上并没有说在微FrimeM中的什么时候(它将是微框架中的16个包中的3个包)。 三。StxFelSead配置在主机控制器驱动程序上分配的缓冲区。假设我配置它为8K,当我触发16K传输,然后在8K填充后,它将被转移到驱动器或PC内存(只是命名,而不是真正的2之间的实际差异),才能得到剩余的8K并发送它。8K在中间的传输增加了延迟。这是SETXFELSIZE出现的场景。 当做, 阿南德 以上来自于百度翻译 以下为原文 2. Yep. descriptor only. 1. It depends on host scheduling. Say you configure descriptor saying 3 packets per microframe for iso, the host will request 3 packets within the microframe but doesn't really say when within that microframe (It will be 3 packets among the 16 packets in the microframe). 3. setxfersize configures the buffer allocated on the host controller driver. Say i configure it for 8k, when i trigger 16k transfer then after 8k fills up it will be transferred to driver or PC memory (just naming, not a real difference between the 2 actually) before it can get the remaining 8k and send it up. This transferring of 8k in the middle adds delay. This is the scenario where setxfersize comes into picture. Regards, Anand |
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谢谢!阿南德!我逐渐理解了StxFelScess,所以如果我想从摄像机CCD传输图像数据,我可以把XFEXSIZE设置成一个图片的大小(即1024×768),当大小是1024倍的时候。1024×768会不会太危险?
以上来自于百度翻译 以下为原文 Thank you!Anand! I gradually understand the setxfersize.So if I want to transfer image data from camera CCD, I can set the Xfersize to be the size of a picture(i.e. 1024*768), when the size is multiple of 1024.is it right? Would the 1024*768 be too larege? |
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