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/*
* Program for finding M & N values for DPLLs
* To be run on Host PC
*
* (C) Copyright 2010
* Texas Instruments, <www.ti.com>
*
* Aneesh V <aneesh@ti.com>
*
* See file CREDITS for list of people who contributed to this
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
#include <stdlib.h>
#include <stdio.h>
typedef unsigned int u32;
#define MAX_N 127
/*
* get_m_n_optimized() - Finds optimal DPLL multiplier(M) and divider(N)
* values based on the reference frequency, required output frequency,
* maximum tolerance for output frequency etc.
*
* target_freq_khz - output frequency required in KHz
* ref_freq_khz - reference(input) frequency in KHz
* m - pointer to computed M value
* n - pointer to computed N value
* tolerance_khz - tolerance for the output frequency. When the algorithm
* succeeds in finding vialble M and N values the corresponding output
* frequency will be in the range:
* [target_freq_khz - tolerance_khz, target_freq_khz]
*
* Formula:
* Fdpll = (2 * M * Fref) / (N + 1)
*
* Considerations for lock-time:
* - Smaller the N, better lock-time, especially lock-time will be
* - For acceptable lock-times:
* Fref / (M + 1) >= 1 MHz
*
* Considerations for power:
* - The difference in power for different N values giving the same
* output is negligible. So, we optimize for lock-time
*
* Hard-constraints:
* - N can not be greater than 127(7 bit field for representing N)
*
* Usage:
* $ gcc clocks_get_m_n.c
* $ ./a.out
*/
int get_m_n_optimized(u32 target_freq_khz, u32 ref_freq_khz, u32 *m, u32 *n,
u32 tolerance_khz)
{
u32 min_freq = target_freq_khz - tolerance_khz;
u32 max_freq = target_freq_khz;
u32 freq, freq_old;
*n = 1;
while (1) {
*m = min_freq / ref_freq_khz / 2 * (*n) ;
freq_old = 0;
while (1) {
freq = ref_freq_khz * 2 * (*m) / (*n);
if (abs(target_freq_khz - freq_old) <=
abs(target_freq_khz - freq)) {
freq = freq_old;
(*m)--;
break;
}
(*m)++;
freq_old = freq;
}
if (freq >= min_freq && freq <= max_freq)
break;
(*n)++;
if ((*n) > MAX_N + 1) {
printf("ref %d m %d n %d target %d : ",
ref_freq_khz, *m, *n, target_freq_khz);
printf("can not find m & n - please consider"
" increasing tolerance\n");
return -1;
}
}
(*n)--;
printf("ref %d m %d n %d target %d locked %d\n",
ref_freq_khz, *m, *n, target_freq_khz, freq);
if ((ref_freq_khz / (*n + 1)) < 1000) {
printf("\tREFCLK - CLKINP/(N+1) is less than 1 MHz - less than"
" ideal, locking time will be high!\n");
}
return 0;
}
void main(void)
{
u32 m, n;
printf("\nMPU - 2000000\n");
get_m_n_optimized(2000000, 12000, &m, &n, 0);
get_m_n_optimized(2000000, 13000, &m, &n, 0);
get_m_n_optimized(2000000, 16800, &m, &n, 800);
get_m_n_optimized(2000000, 19200, &m, &n, 0);
get_m_n_optimized(2000000, 26000, &m, &n, 0);
get_m_n_optimized(2000000, 27000, &m, &n, 0);
get_m_n_optimized(2000000, 38400, &m, &n, 0);
printf("\nMPU - 1200000\n");
get_m_n_optimized(1200000, 12000, &m, &n, 0);
get_m_n_optimized(1200000, 13000, &m, &n, 0);
get_m_n_optimized(1200000, 16800, &m, &n, 800);
get_m_n_optimized(1200000, 19200, &m, &n, 0);
get_m_n_optimized(1200000, 26000, &m, &n, 0);
get_m_n_optimized(1200000, 27000, &m, &n, 0);
get_m_n_optimized(1200000, 38400, &m, &n, 0);
printf("\nMPU - 1584000\n");
get_m_n_optimized(1584000, 12000, &m, &n, 0);
get_m_n_optimized(1584000, 13000, &m, &n, 0);
get_m_n_optimized(1584000, 16800, &m, &n, 400);
get_m_n_optimized(1584000, 19200, &m, &n, 0);
get_m_n_optimized(1584000, 26000, &m, &n, 0);
get_m_n_optimized(1584000, 27000, &m, &n, 0);
get_m_n_optimized(1584000, 38400, &m, &n, 0);
printf("\nCore 1600000\n");
get_m_n_optimized(1600000, 12000, &m, &n, 0);
get_m_n_optimized(1600000, 13000, &m, &n, 0);
get_m_n_optimized(1600000, 16800, &m, &n, 200);
get_m_n_optimized(1600000, 19200, &m, &n, 0);
get_m_n_optimized(1600000, 26000, &m, &n, 0);
get_m_n_optimized(1600000, 27000, &m, &n, 0);
get_m_n_optimized(1600000, 38400, &m, &n, 0);
printf("\nPER 1536000\n");
get_m_n_optimized(1536000, 12000, &m, &n, 0);
get_m_n_optimized(1536000, 13000, &m, &n, 0);
get_m_n_optimized(1536000, 16800, &m, &n, 0);
get_m_n_optimized(1536000, 19200, &m, &n, 0);
get_m_n_optimized(1536000, 26000, &m, &n, 0);
get_m_n_optimized(1536000, 27000, &m, &n, 0);
get_m_n_optimized(1536000, 38400, &m, &n, 0);
printf("\nIVA 1862000\n");
get_m_n_optimized(1862000, 12000, &m, &n, 0);
get_m_n_optimized(1862000, 13000, &m, &n, 0);
get_m_n_optimized(1862000, 16800, &m, &n, 0);
get_m_n_optimized(1862000, 19200, &m, &n, 900);
get_m_n_optimized(1862000, 26000, &m, &n, 0);
get_m_n_optimized(1862000, 27000, &m, &n, 0);
get_m_n_optimized(1862000, 38400, &m, &n, 800);
printf("\nABE 196608 sys clk\n");
get_m_n_optimized(196608, 12000, &m, &n, 700);
get_m_n_optimized(196608, 13000, &m, &n, 200);
get_m_n_optimized(196608, 16800, &m, &n, 700);
get_m_n_optimized(196608, 19200, &m, &n, 400);
get_m_n_optimized(196608, 26000, &m, &n, 200);
get_m_n_optimized(196608, 27000, &m, &n, 900);
get_m_n_optimized(196608, 38400, &m, &n, 0);
printf("\nABE 196608 32K\n");
get_m_n_optimized(196608000/4, 32768, &m, &n, 0);
printf("\nUSB 1920000\n");
get_m_n_optimized(1920000, 12000, &m, &n, 0);
get_m_n_optimized(1920000, 13000, &m, &n, 0);
get_m_n_optimized(1920000, 16800, &m, &n, 0);
get_m_n_optimized(1920000, 19200, &m, &n, 0);
get_m_n_optimized(1920000, 26000, &m, &n, 0);
get_m_n_optimized(1920000, 27000, &m, &n, 0);
get_m_n_optimized(1920000, 38400, &m, &n, 0);
printf("\nCore ES1 1523712\n");
get_m_n_optimized(1524000, 12000, &m, &n, 100);
get_m_n_optimized(1524000, 13000, &m, &n, 0);
get_m_n_optimized(1524000, 16800, &m, &n, 0);
get_m_n_optimized(1524000, 19200, &m, &n, 0);
get_m_n_optimized(1524000, 26000, &m, &n, 0);
get_m_n_optimized(1524000, 27000, &m, &n, 0);
/* exact recommendation for SDPs */
get_m_n_optimized(1523712, 38400, &m, &n, 0);
}
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