Microchip PIC 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

This application is mirrored at:

• http://www.golovchenko.org/cgi-bin/delay
• http://www.piclist.com/cgi-bin/delay.exe

Also:

• Multiplication and division by a constant 
• Keyword matching in a serial text stream
• Convert Binary to Decimal for A2D Converter output
• The character set extractor

See:

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

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:

• @spam@ptdpublic@spam@ at ~NOSPAM~mac.com " This is very cool. I've included link back to this generator in comments and provided credit in my code. thank you" +
• WOW Exellent Idea, Excellent Implementation!!

PICList 2013 contributors: o List host: MIT, Site host massmind.org, Top posters @20130524 RussellMc, IVP, Bob Blick, alan.b.pearce, John Gardner, veegee, Sean Breheny, Isaac Marino Bavaresco, Carl Denk, Josh Koffman, * 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: None at this time. on-going support is MOST appreciated! * Contributors: Richard Seriani, Sr.

  .