1 /*
2 * Copyright (C) 2014 BlueKitchen GmbH
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the copyright holders nor the names of
14 * contributors may be used to endorse or promote products derived
15 * from this software without specific prior written permission.
16 * 4. Any redistribution, use, or modification is done solely for
17 * personal benefit and not for any commercial purpose or for
18 * monetary gain.
19 *
20 * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS
21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
23 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL BLUEKITCHEN
24 * GMBH OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
26 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
27 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
28 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
29 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
30 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * Please inquire about commercial licensing options at
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35 *
36 */
37
38
39 /*
40 * hal_tick.c
41 *
42 * Implementation for MSP430 Experimenter board using 250 ms ticks provided by Timer A1
43 *
44 */
45
46 #include <msp430.h>
47 #include <stdlib.h>
48 #include "hal_compat.h"
49
50 #include "hal_tick.h"
51
dummy_handler(void)52 static void dummy_handler(void){};
53
54 static void (*tick_handler)(void) = &dummy_handler;
55
56 // Auxillary Clock (ACLK) = 32768 hz
57 // 8192 ticks = 1/4 second
58
59 #define TIMER_COUNTDOWN 8192
60
hal_tick_init(void)61 void hal_tick_init(void){
62 TA1CCTL0 = CCIE; // CCR0 interrupt enabled
63 TA1CTL = TASSEL_1 | MC_2 | TACLR; // use ACLK (32768), contmode, clear TAR
64 TA1CCR0 = TIMER_COUNTDOWN; // -> 1/4 s
65 }
66
hal_tick_set_handler(void (* handler)(void))67 void hal_tick_set_handler(void (*handler)(void)){
68 if (handler == NULL){
69 tick_handler = &dummy_handler;
70 return;
71 }
72 tick_handler = handler;
73 }
74
hal_tick_get_tick_period_in_ms(void)75 int hal_tick_get_tick_period_in_ms(void){
76 return 250;
77 }
78
79 // Timer A1 interrupt service routine
80 #ifdef __GNUC__
81 __attribute__((interrupt(TIMER1_A0_VECTOR)))
82 #endif
83 #ifdef __IAR_SYSTEMS_ICC__
84 #pragma vector=TIMER1_A0_VECTOR
85 __interrupt
86 #endif
timerA0ISR(void)87 void timerA0ISR(void){
88 TA1CCR0 += TIMER_COUNTDOWN;
89 (*tick_handler)();
90
91 // force exit low power mode
92 __bic_SR_register_on_exit(LPM0_bits); // Exit active CPU
93 }
94