The problem of USB Write data Speed in Slave FIFO mode using CY7C68013A ? | Cypress Semiconductor
The problem of USB Write data Speed in Slave FIFO mode using CY7C68013A ?
Chip using CY7C68013A-56LTXC, GPIF clock frequency is set to 20MHz, uses a 16-bit bandwidth.The work mode is Slave FIFO mode, GPIF connection is Spartan 6 FPGA.USB write speeds were tested under Windows XP environment. Program every 10ms to write 10KByte USB port data, the time required for each test. Testing found that: minimum time is 470us, almost able to speed 20MB / s, more than 10ms maximum when used. USB port and multiple write statistics: 10KByte write data to a USB port, 70% of the time in less than 1ms, 20% ~ 30% longer than 1ms and less than 3ms, the rest of the time more than 10ms. What causes more than 10ms? Appears this normal? How to avoid using too long? What method can be used to control this time in 2ms?