Roman, Let me see if I have this right. I adjust the period until I get bit change in the counter. However the pulse width will be constant (actually a very very slowly changing - to the extent of being constant) so effectively changing the period will only change duty cycle. Maybe I'm being obtuse but I can't see how this will improve the resolution if I'm running with a system clock of 1uS. Initially I thought you were suggesting a the use of dither to get the resolution, but as far as I remember dither will help resolve and additional 1/2LSB which will gain only 500uS. For the application I would really need 250nS resolution on the width of the pulse. I'll give what I was proposing a shot and I'll let you know how it gets on. Slan John *************************************************************** John.Walshe@inpactmicro.com INPACT MICROELECTRONICS (Irl) Ltd 21A Pouladuff Road, Cork, Ireland, Tel: +353 21 4318296 Fax: +353 21 4318980 WWW.INPACTMICRO.COM *************************************************************** -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.