Delay Code Generator

For long delays (> 10 cycles) the code is based on nested loops using 'decfsz' and 'goto' instructions. Small delays are built using 'goto $ + 1' (2 cycles delay) and 'nop' (one cycle delay).

To calculate nested loop counter values the code generator uses an optimum search algorithm. The algorithm finds such values for counters that achieve good approximation to the specified delay.

Even if there is an error in the first block of nested loops, the rest of the code fixes that. As a result, one cycle resolution is achieved.

Idea: James Newton
Implementation: Nikolai Golovchenko

See:

• /techref/microchip/12ceeprom.htm proper initialization delays for 12cxxx EEPROM access
• PIC Specific delays
• SX Specific delays

See also:

• http://www.disall.narod.ru/prog.htm PIC Delay routine
• http://www.mnsi.net/~boucher/picloops.html
• http://www.golovchenko.org/cgi-bin/delay

Questions:

Daniel Chia Jin Hao Says:

For PIC18, this delay routine will need a little modification to work properly.. the goto $+1 within the delay loops that sometimes appears needs to be changed to goto $+6, since each program word is 2 bytes, and goto is a 4 byte instruction. Also, at the end sometimes goto $+1 is used as a 2 cycle delay, need to use goto $+4 to skip over the whole goto.

I hope this is correct, AFAIK it is.

Comments:

PICList 2008 contributors: o List host: MIT, Site host massmind.org, Top posters @20081120 Apptech, Jinx, Xiaofan Chen, olin piclist, Vitaliy, William \Chops\ Westfield, Tamas Rudnai, Alan B. Pearce, JonnyMac, Gerhard Fiedler, * Page Editors: James Newton, David Cary, and YOU! * Roman Black of Black Robotics donates from sales of Linistep stepper controller kits. * Ashley Roll of Digital Nemesis donates from sales of RCL-1 RS232 to TTL converters. * Monthly Subscribers: Shultz Electronics, Timothy Weber, on-going support is MOST appreciated! * Contributors: Richard Seriani, Sr.

  .