2 * Copyright © 2012 Robert D. Garbee <robert@gag.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; version 2 of the License.
8 * This program is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
13 * You should have received a copy of the GNU General Public License along
14 * with this program; if not, write to the Free Software Foundation, Inc.,
15 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
22 * This code implements a PWM input using ICP3.
24 * The initial use is to measure wind speed in the ULA/Ball summer intern
25 * project payload developed at Challenger Middle School.
28 volatile __data uint16_t ao_icp3_count;
31 ao_pwmin_display(void) __reentrant
33 /* display the most recent value */
34 printf("icp 3: %5u\n", ao_icp3_count);
41 ao_icp3_count = (hi <<8) | lo;
44 __code struct ao_cmds ao_pwmin_cmds[] = {
45 { ao_pwmin_display, "p\0PWM input" },
52 /* do hardware setup here */
53 TCCR3A = ((0 << WGM31) | /* normal mode, OCR3A */
54 (0 << WGM30)); /* normal mode, OCR3A */
55 TCCR3B = ((1 << ICNC3) | /* input capture noise canceler on */
56 (0 << ICES3) | /* input capture on falling edge (don't care) */
57 (0 << WGM33) | /* normal mode, OCR3A */
58 (0 << WGM32) | /* normal mode, OCR3A */
59 (4 << CS30)); /* clk/256 from prescaler */
63 TIMSK3 = (1 << ICIE3); /* Interrupt on input compare */
65 /* set the spike filter bit in the TCCR3B register */
67 ao_cmd_register(&ao_pwmin_cmds[0]);