FTDI Community
General Category => Discussion - Hardware => Topic started by: IanPo on January 15, 2019, 08:37:00 AM
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Hello!
Description of the problem:
External chip (say, FPGA) is writing a data into FTDI (2)232H chip.
After first ( in fact, after every ) 510 bytes TXE# suddenly goes up and you have data loss.
The document AN_130 says: "Although the RX and TX buffers are 4KB, they only use 2x 512 bytes for each buffer under FT245 Synchronous FIFO mode", so we would expect buffer override after 1024 bytes sent.
My workaround here is the following:
to use TXE# as WAIT signal (send new data only if TXE# is low and wait if it goes high).
After first 510 sent TXE# goes high for 10 clocks (~170 ns).
I added some diagrams taken with logic analyzer.
If you know any other solutions (driver fixed, maybe) it would be nice to see them.
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Hello,
There are two status bytes sent at the start of every packet (covered by NDA) when using FT245 Synchronous FIFO mode. Thus each packet only contains 510 data bytes, and two status bytes making up the 512 byte buffer.
Best Regards,
FTDI Community