Jan, > What do you mean with “and a small sck period”
The smaller the SCK period the faster the programmer tries to program the target mcu. There are limits and not all programmers/software support user altering of the SCK period. I think you mentioned you use a Pololu programmer so this link might help. https://www.pololu.com/docs/0J67/5.7 Best wishes, Tristan _______________________________________________ Amforth-devel mailing list for http://amforth.sf.net/ Amforth-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/amforth-devel
