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CPU usage for BulkIn | Cypress Semiconductor

CPU usage for BulkIn

Summary: 1 Reply, Latest post by Madhu Sudhan on 19 Oct 2015 11:26 PM PDT
Verified Answers: 0
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Benjamnin Couture's picture
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I'm trying to figure out what is the CPU usage for BulkIn operation. I'm streaming from the GPIF at a rate of 4.5MB/s. My issue is that the streaming must continuously stream uninterrupted for weeks. I won't go Iso because each bit is critical. I might even include a Byte counter to certify every word. 


So when the Command is executed, is the CPU busy during the whole time of the transfer? How much transfer there is between each CPU usage. There is many buffer levels in those transfers. Which buffer level requires only one initialization and then becomes CPU free while transferring?

The problem is that windows8 sometime takes the whole CPU for some internal maintenance (even when the computer is configured and is stripped to the minimum). Depending on how much data can be transfer without CPU will result in how much time can window be a jerk.

It's hard to find the info on the lowest level of the USB functioning. Is it using DMA to transfer memory to a buffer somewhere? Is there any memory transfer without CPU usage?

mady's picture
Cypress Employee
964 posts


The way DMA and CPU work is specific to a PC. However in most of the cases, normal CPU usage will not affect USB transfer even when it runs the internal maintenance.


-Madhu Sudhan


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