/* * Program for finding M & N values for DPLLs * To be run on Host PC * * (C) Copyright 2010 * Texas Instruments, * * Aneesh V * * 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 #include 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); }