Hi,
On 24/01/16 19:34, Rogier Wolff wrote:
Hi,
Occasional reader, here...
On Sat, Jan 23, 2016 at 03:29:50PM +0100, Johan Ström wrote:
c) Would it make sense for libftdi to set rts/dts defaults to 1, as
both Linux and FreeBSD seems to do this (when opening as a regular
serial port)? Although, devices may use RTS/DTR for any purpose, it
might be best to leave it alone..?
The setting of CTS/RTS is "standard" when opening a serial port. The
default for those signals is "inactive": "please don't send anything,
there is (probably) nobody listening".
Once you open the port, the signal should go active: "we're listening,
go ahead, send data.".
However, for "other-than-standard-serial-port" devices, where you'd
want a libftdi driver, the signal might be used for completely
different purposes. Say: "Detonate the bomb".
So a default in libftdi to set the signal might not be a good idea.
If you need it, the "set the signal" belongs in the layer that uses
libftdi. "libow" or whatever it is called in your case.
Roger.
Yep, all good examples of why it would be a bad idea! Don't want to blow
any bombs prematurely.. :)
One thing I don't understand though.. the RTS pin of the FTDI chip isn't
actually tied to the chip (a PIC with RX/TX), as far as I know.. I
cannot open the device to verify, but there is a similar device for OEM
installations, and this does not expose anything but RX/TX..
So not sure why enabling RTS is required in this case.. Any ideas?
Anyway, anyone who does standard-serial-port stuff needs to be aware
that this should be done!
In my case, the only reason I use libftdi directly is to be able to tune
down the latency timer, to increases the throughput (a lot when dealing
with small transfers).
Johan
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libftdi - see http://www.intra2net.com/en/developer/libftdi for details.
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