FTDI Community

General Category => Discussion - Drivers => Topic started by: mikewu99 on September 17, 2019, 04:29:18 PM

Title: First asynch FIFO read always takes 3 seconds
Post by: mikewu99 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.

Title: Re: First asynch FIFO read always takes 3 seconds
Post by: FTDI Community 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 (https://www.ftdichip.com/Support/Documents/TechnicalNotes/TN_167_FIFO_Basics.pdf) for some useful information and basic test code.

Has your application set flow control for RTS_CTS?

Best Regards,
FTDI Community

Title: Re: First asynch FIFO read always takes 3 seconds
Post by: mikewu99 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.