/usr/share/common-lisp/source/cluck/clock.lisp is in cl-cluck 0.1.3-2.
This file is owned by root:root, with mode 0o644.
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;;;; *************************************************************************
;;;; FILE IDENTIFICATION
;;;;
;;;; Name: cluck.lisp
;;;; Purpose: Common Lisp uControler Clock Calculator
;;;; Programmer: Kevin M. Rosenberg
;;;; Date Started: March 2007
;;;;
;;;; $Id$
;;;;
;;;; Copyright (c) 2007 Kevin M. Rosenberg
;;;;
;;;; Redistribution and use in source and binary forms, with or without
;;;; modification, are permitted provided that the following conditions
;;;; are met:
;;;; 1. Redistributions of source code must retain the above copyright
;;;; notice, this list of conditions and the following disclaimer.
;;;; 2. Redistributions in binary form must reproduce the above copyright
;;;; notice, this list of conditions and the following disclaimer in the
;;;; documentation and/or other materials provided with the distribution.
;;;; 3. Neither the name of the author nor the names of the contributors
;;;; may be used to endorse or promote products derived from this software
;;;; without specific prior written permission.
;;;;
;;;; THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
;;;; ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
;;;; IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
;;;; ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
;;;; FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
;;;; DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
;;;; OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
;;;; HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
;;;; LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
;;;; OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
;;;; SUCH DAMAGE.
;;;; *************************************************************************
(in-package #:cluck)
(defvar *f-cpu* 16000000)
(defvar *8-bit-prescalars* '(1 8 64 256))
(defvar *10-bit-prescalars* '(1 8 64 256 1024))
(defvar *base-error-zero-baud-clk* (* 9 25 8192)
"Base multiple for multi-megahertz clock frequencies to have
0% error at common UART baud rates. Value of this base is 1.8432 million.
Common multiples of this are 2 (3.6864Mhz), 4 (7.3728Mhz), 8 (14745600),
and 10 (18.432MHz)")
(defun show-timers (f-cpu prescalers width)
(let ((max-count (expt 2 width)))
(format t "~&Prescalar MaxRate MinUS MinRate MaxMS~%")
(dolist (prescale prescalers)
(let ((base (/ f-cpu prescale)))
(format t "~4D ~12,1F ~9,3F ~10,4F ~13,3F~%"
prescale
(coerce base 'float)
(coerce (/ 1000000 base) 'float)
(coerce (/ base max-count) 'float)
(coerce (/ 1000 (/ base max-count)) 'float))))))
(defun show-8-bit-timers (&optional (f-cpu *f-cpu*))
(show-timers f-cpu *10-bit-prescalars* 8))
(defun show-16-bit-timers (&optional (f-cpu *f-cpu*))
(show-timers f-cpu *10-bit-prescalars* 16))
(defun show-32-bit-timers (&optional (f-cpu *f-cpu*))
"Show max/min periods for 32-bit timers. For 16-bit PIC
controllers, 32-bit timers use 8-bit prescalers"
(show-timers f-cpu *8-bit-prescalars* 32))
(defun ms-timer-width (ms f-cpu prescalars width)
"Returns the prescalar and compare count for both 8 and 16 bit timers."
(labels ((nearest-count (prescale)
(let ((count (round (* ms (/ f-cpu 1000 prescale))))
(max-count (expt 2 width)))
(cond
((< count 1)
1)
((<= count max-count)
count)
((> max-count)
max-count))))
(clk-ms (prescale count)
(unless (zerop count)
(/ count (/ f-cpu 1000 prescale))))
(percent-error (actual desired)
(* 100 (- (/ actual desired) 1))))
(dolist (prescale prescalars)
(let* ((count (nearest-count prescale))
(clk-ms (clk-ms prescale count))
(err (percent-error clk-ms ms))
(fmt-err (if (> err 1000)
" >1000%"
(format nil "~8,3F%" err))))
(format t "~2D ~4D ~5D ~10,4F ~A~%"
width prescale count clk-ms fmt-err)))))
(defun ms-timer (ms &optional (f-cpu *f-cpu*))
"Returns the prescalar and compare count for both 8 and 16 bit timers."
(dolist (width '(8 16))
(ms-timer-width ms f-cpu *10-bit-prescalars* width)))
(defconstant* +baud-rates+ '(300 600 1200 2400 4800 9600 14400 19200 28800
38400 56000 57600 76800 115200 128000 250000
256000 500000))
(defun avr-uart-divisors (&optional (f-cpu *f-cpu*) (view-below-percent nil))
"Displays the divisor UBRR and error percent for various baud
rates for F_CPU. UBBR is limited to 12 bits."
(dolist (baud +baud-rates+)
(let* ((ubrr (min 4096
(max 0 (round (- (/ f-cpu 16 baud) 1)))))
(ubrr2 (min 4096
(max 0 (round (- (/ f-cpu 8 baud) 1)))))
(actual-baud (/ f-cpu 16 (1+ ubrr)))
(actual-baud2 (/ f-cpu 8 (1+ ubrr2)))
(err (* 100 (- (/ actual-baud baud) 1)))
(err2 (* 100 (- (/ actual-baud2 baud) 1))))
(when (or (not view-below-percent)
(or (< (abs err) view-below-percent)
(< (abs err2) view-below-percent)))
(format t "~6D ~4D ~5,1F% ~4D ~5,1F%~%"
baud ubrr err ubrr2 err2)))))
(defun pic-uart-divisors (&optional (fcy *f-cpu*) (view-below-percent nil))
"Displays the divisor BRG and error percent for various baud
rates for Fcy. BRG is limited to 16 bits."
(dolist (baud +baud-rates+)
(let* ((brg (min 65536
(max 0 (round (- (/ fcy 16 baud) 1)))))
(actual-baud (/ fcy 16 (1+ brg)))
(err (* 100 (- (/ actual-baud baud) 1))))
(when (or (not view-below-percent)
(< (abs err) view-below-percent))
(format t "~6D ~4D ~5,1F%~%" baud brg err)))))
(defun zero-error-uart-clocks ()
(dolist (mult '(1 2 4 6 8 10 12))
(format t "~&~8,4F MHz~%" (* mult *base-error-zero-baud-clk* 1e-6))))
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