libftdi Archives

Subject: Re: Writing EEPROM on FT232R / FT245R

From: Jim Paris <jim@xxxxxxxx>
To: libftdi@xxxxxxxxxxxxxxxxxxxxxxx
Date: Fri, 27 Mar 2009 15:44:53 -0400
Karl Cunningham wrote:
> I just subscribed to this list because I had the same situation as
> Marius Kintel did in his original post of the thread started on 25 Feb
> 2009 -- trouble programming an FT245R with libftdi. My apologies that
> this message will likely not be threaded into the original in the archives.
>
> In the email in this thread on 12-Mar-09 from Jim Paris and in the FTDI  
> datasheet, I see mention of setting the latency timer to 77 (decimal)  
> milliseconds to program the FT245R. The patch appears to set it to 0x77  
> (hex) ms.
>
> I assume the value of 77ms is a minimum and 0x77 seems to work fine too,  
> but I wanted to point this out in case it matters to anyone.

Hi Karl,

I'm aware of this discrepency -- it's from the FTDI document at
  
http://www.ftdichip.com/Documents/AppNotes/AN_105_FTDI_Device_Programming_Using_Vinculum_VNC1L(FT_000078).pdf
which says 77ms.  I'm pretty sure this is just a typo, and it should
have read 119ms.

0x77 is the number we want, since that's what the AN-105 example code
shows, it's what MPROG uses under Windows, and it's what the D2XX
Linux drivers use in FT_EE_Program.

Thanks,
-jim


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