[ntp:questions] WinXP no DCD interupts unless RTS/CTS handshaking enabled

David Taylor david-taylor at blueyonder.co.uk.invalid
Thu Apr 10 15:59:22 UTC 2014

On 10/04/2014 09:49, James Gibb wrote:
> I'm not sure if this is a generic problem or something weird has happened to the UARTs on my box, but I find I only see DCD events if RTS/CTS handshaking is on.  This is true for David Taylor's SerialPort LEDs viewer, RealTerm (a Windows terminal/debugging program) and NTPd.  I've hacked refclock_open to set the DCB flags fOutxCtsFlow to 1 and fRtsControl to RTS_CONTROL_HANDSHAKE and it sees PPS; otherwise it does not.
> Now, last week it was seeing the PPS without those hacks.  Since then I've disconnected an oscilloscope and re-worked the wiring around a level converter which temporarily broke PPS at the wire level.  I can't remember using anything except the LED viewer and RealTerm to check I'd got it working again and I had used both prior to that and they didn't cause this interrupt disabling.
> Anyone any ideas what's happened?
> // James Gibb

James, that doesn't rung any bells with me in software, perhaps you 
damaged more than just the PPS line when working on the interface.  A 
flake of solder, perhaps?  But that's just a guess.

There's nothing special in the Serial Port LEDs program which would 
require that.
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