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Note
titleIt is necessary that a FW/HW routine reads USB FX2 microcontroller's EP8 buffer.

If the EP6's buffer is not is not properly written by the FPGA(reference design)/other(custom design) the EP6's buffer will become empty and the host computer will be no longer able to receive further packets. In this case the TE_USB_FX2_GetData() function could experience strange behaviors. For example, a very low throughput (9-10 Mbyte/s even if a 31-38 Mbyte/s are expected) could be measured or the function TE_USB_FX2_GetData() fails returning false.

During USB read transmission test (RX: host computer perspective) the EP6's buffer writing is carried out by MicroBlaze (inside the FPGA); this behavior is setted by MicroBlaze API command FX22MB_REG0_START_TX (TX: USB FX2 microcontroller perspective)

Code Block
languagecpp
SendFPGAcommand(USBDeviceList,FX22MB_REG0_START_TX);

Expected Data Throughput 

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The maximum data throughput expected (with a DataReadLength= 120*10^6) is 38 Mbyte/s (PacketSize = BufferSize = 102400), but in fact this value is variable between 31-38 Mbyte/s (the mean value seems 33.5 Mbyte/s); so if you measure this range of values, the data reception can be considered as normal.

Note

The data throughput is variable in two ways:

  • depends on the used host computer;
  • varies with every function call (computer loading dependent).

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