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//
// Copyright (C) 2015 Clifford Wolf <clifford@clifford.at>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
//
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <math.h>
const char *binstr(int v, int n)
{
static char buffer[16];
char *p = buffer;
for (int i = n-1; i >= 0; i--)
*(p++) = ((v >> i) & 1) ? '1' : '0';
*(p++) = 0;
return buffer;
}
void help(const char *cmd)
{
printf("\n");
printf("Usage: %s [options]\n", cmd);
printf("\n");
printf(" -i <input_freq_mhz>\n");
printf(" PLL Input Frequency (default: 12 MHz)\n");
printf("\n");
printf(" -o <output_freq_mhz>\n");
printf(" PLL Output Frequency (default: 60 MHz)\n");
printf("\n");
printf(" -S\n");
printf(" Disable SIMPLE feedback path mode\n");
printf("\n");
exit(1);
}
int main(int argc, char **argv)
{
double f_pllin = 12;
double f_pllout = 60;
bool simple_feedback = true;
int opt;
while ((opt = getopt(argc, argv, "i:o:S")) != -1)
{
switch (opt)
{
case 'i':
f_pllin = atof(optarg);
break;
case 'o':
f_pllout = atof(optarg);
break;
case 'S':
simple_feedback = false;
break;
default:
help(argv[0]);
}
}
if (optind != argc)
help(argv[0]);
bool found_something = false;
double best_fout = 0;
int best_divr = 0;
int best_divf = 0;
int best_divq = 0;
if (f_pllin < 10 || f_pllin > 133) {
fprintf(stderr, "Error: PLL input frequency %.3f MHz is outside range 10 MHz - 133 MHz!\n", f_pllin);
exit(1);
}
if (f_pllout < 16 || f_pllout > 275) {
fprintf(stderr, "Error: PLL output frequency %.3f MHz is outside range 16 MHz - 275 MHz!\n", f_pllout);
exit(1);
}
for (int divr = 0; divr <= 15; divr++)
{
double f_pfd = f_pllin / (divr + 1);
if (f_pfd < 10 || f_pfd > 133) continue;
for (int divf = 0; divf <= 127; divf++)
{
if (simple_feedback)
{
double f_vco = f_pfd * (divf + 1);
if (f_vco < 533 || f_vco > 1066) continue;
for (int divq = 1; divq <= 6; divq++)
{
double fout = f_vco * exp2(-divq);
if (fabs(fout - f_pllout) < fabs(best_fout - f_pllout) || !found_something) {
best_fout = fout;
best_divr = divr;
best_divf = divf;
best_divq = divq;
found_something = true;
}
}
}
else
{
for (int divq = 1; divq <= 6; divq++)
{
double f_vco = f_pfd * (divf + 1) * exp2(divq);
if (f_vco < 533 || f_vco > 1066) continue;
double fout = f_vco * exp2(-divq);
if (fabs(fout - f_pllout) < fabs(best_fout - f_pllout) || !found_something) {
best_fout = fout;
best_divr = divr;
best_divf = divf;
best_divq = divq;
found_something = true;
}
}
}
}
}
double f_pfd = f_pllin / (best_divr + 1);;
double f_vco = f_pfd * (best_divf + 1);
if (!simple_feedback)
f_vco *= exp2(best_divq);
if (!found_something) {
fprintf(stderr, "Error: No valid configuration found!\n");
exit(1);
}
printf("\n");
printf("F_PLLIN: %8.3f MHz (given)\n", f_pllin);
printf("F_PLLOUT: %8.3f MHz (requested)\n", f_pllout);
printf("F_PLLOUT: %8.3f MHz (achieved)\n", best_fout);
printf("\n");
printf("FEEDBACK: %s\n", simple_feedback ? "SIMPLE" : "NON_SIMPLE");
printf("F_PFD: %8.3f MHz\n", f_pfd);
printf("F_VCO: %8.3f MHz\n", f_vco);
printf("\n");
printf("DIVR: %2d (4'b%s)\n", best_divr, binstr(best_divr, 4));
printf("DIVF: %2d (7'b%s)\n", best_divf, binstr(best_divf, 7));
printf("DIVQ: %2d (3'b%s)\n", best_divq, binstr(best_divq, 3));
printf("\n");
return 0;
}
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