2 * Copyright © 2012 Keith Packard <keithp@keithp.com>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
14 * You should have received a copy of the GNU General Public License along
15 * with this program; if not, write to the Free Software Foundation, Inc.,
16 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
22 * The provided 'calibration' value is
23 * that needed to tune the radio to precisely 434550kHz.
24 * The relation between value and freq is linear, so
25 * to get the value for an arbitrary frequency:
27 * target_value target_freq
28 * ------------ = ------------
31 * cal_value * target_freq
32 * target_value = -----------------------
36 uint32_t ao_freq_to_set(uint32_t target_freq, uint32_t cal_value)
38 uint64_t prod = (uint64_t) target_freq * (uint64_t) cal_value;
40 /* Round to nearest */
41 uint32_t target_value = (uint32_t) ((prod + (434550U / 2U)) / 434550U);