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Author Topic: First asynch FIFO read always takes 3 seconds  (Read 100 times)

mikewu99

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First asynch FIFO read always takes 3 seconds
« on: September 17, 2019, 04:29:18 PM »

Chip: FT2232H
Configuration: Channel A is SPI interface (MPSSE); Channel B is asynchronous FIFO
Driver Version: 2.12.28.0
Software: Microsoft C# using FTD2XX_NET Managed Wrapper version 1.1.0

First FT_Read (through the Read method in the wrapper) on the asynchronous FIFO always takes slightly more than three seconds. Subsequent reads are very fast. If I do an write first followed by a read the write executes very quickly but the subsequent read still takes 3 seconds.

Is this normal operation?

ETA: Changing the timeout values does not change the 3 second delay.
« Last Edit: September 17, 2019, 04:57:20 PM by mikewu99 »
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FTDI Community

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Re: First asynch FIFO read always takes 3 seconds
« Reply #1 on: September 19, 2019, 04:36:51 PM »

Hello Mike,

Which OS are you using?

Have you tested without the C# wrapper?

See TN_167 FTDI FIFO Basics for some useful information and basic test code.

Has your application set flow control for RTS_CTS?

Best Regards,
FTDI Community
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mikewu99

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Re: First asynch FIFO read always takes 3 seconds
« Reply #2 on: September 19, 2019, 10:10:16 PM »

Never mind - bug elsewhere in code was inadvertently triggering a Xilinx reprogram which apparently takes a bit over 3 seconds.
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