1 /**
2 * \file
3 *
4 * \brief ARM functions for busy-wait delay loops
5 *
6 * Copyright (c) 2014-2015 Atmel Corporation. All rights reserved.
7 *
8 * \asf_license_start
9 *
10 * \page License
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions are met:
14 *
15 * 1. Redistributions of source code must retain the above copyright notice,
16 * this list of conditions and the following disclaimer.
17 *
18 * 2. Redistributions in binary form must reproduce the above copyright notice,
19 * this list of conditions and the following disclaimer in the documentation
20 * and/or other materials provided with the distribution.
21 *
22 * 3. The name of Atmel may not be used to endorse or promote products derived
23 * from this software without specific prior written permission.
24 *
25 * 4. This software may only be redistributed and used in connection with an
26 * Atmel microcontroller product.
27 *
28 * THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR IMPLIED
29 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
30 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE
31 * EXPRESSLY AND SPECIFICALLY DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR
32 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
36 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
38 * POSSIBILITY OF SUCH DAMAGE.
39 *
40 * \asf_license_stop
41 *
42 */
43 /*
44 * Support and FAQ: visit <a href="http://www.atmel.com/design-support/">Atmel Support</a>
45 */
46
47 #include "delay.h"
48
49 /**
50 * Value used to calculate ms delay. Default to be used with a 8MHz clock;
51 */
52 static uint32_t cycles_per_ms = 8000000UL / 1000;
53 static uint32_t cycles_per_us = 8000000UL / 1000000;
54
55 /**
56 * \brief Initialize the delay driver.
57 *
58 * This must be called during start up to initialize the delay routine with
59 * the current used main clock. It must run any time the main CPU clock is changed.
60 */
delay_init(void)61 void delay_init(void)
62 {
63 cycles_per_ms = system_gclk_gen_get_hz(0);
64 cycles_per_ms /= 1000;
65 cycles_per_us = cycles_per_ms / 1000;
66
67 SysTick->CTRL = SysTick_CTRL_CLKSOURCE_Msk | SysTick_CTRL_ENABLE_Msk;
68 }
69
70 /**
71 * \brief Delay loop to delay at least n number of microseconds
72 *
73 * \param n Number of microseconds to wait
74 */
delay_cycles_us(uint32_t n)75 void delay_cycles_us(
76 uint32_t n)
77 {
78 while (n--) {
79 /* Devide up to blocks of 10u */
80 delay_cycles(cycles_per_us);
81 }
82 }
83
84 /**
85 * \brief Delay loop to delay at least n number of milliseconds
86 *
87 * \param n Number of milliseconds to wait
88 */
delay_cycles_ms(uint32_t n)89 void delay_cycles_ms(
90 uint32_t n)
91 {
92 while (n--) {
93 /* Devide up to blocks of 1ms */
94 delay_cycles(cycles_per_ms);
95 }
96 }
97