Subject: Re: Hi-speed UARTs (3Mbps to 12Mbps) on FT2232H/FT4232H
On Tuesday, 4. May 2010 18:08:32 Emmanuel Blot wrote:
> I have not found a reference to this feature in the current FTDI lib,
> sorry if a patch has already been posted.
> Here is a quick patch to the current libftdi GIT HEAD to support
> hi-speed baudrates on recent FTDI devices
> I've kept the original 5% tolerance on UART speed, although many
> devices do not tolerate such a drift at hi baudrates (I'm using a 3%
> max tolerance with my own devices)
Thanks for your patch! Some small questions:
- FTDI_BAUDRATE_TOLERANCE doesn't seem to get used?
- Could you check if this piece of code doesn't break
the bitbang mode as it multiplies the baud rate by four:
+ if ( baudrate > (FTDI_BAUDRATE_REF_CLOCK>>1) )
+ ref_clock *= 4; // 12 MHz
+ hispeed = 1;
I haven't looked at the baudrate code in a long time...
- Where does this "magic" come from: "*index |= 1<<9; // use hispeed mode"?
Maybe a #define would be nice to give it a concrete name.
libftdi - see http://www.intra2net.com/en/developer/libftdi for details.
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