/cpu/cc253x/dev/clock.c

  1/*
  2 * Copyright (c) 2009, Swedish Institute of Computer Science.
  3 * All rights reserved.
  4 *
  5 * Redistribution and use in source and binary forms, with or without
  6 * modification, are permitted provided that the following conditions
  7 * are met:
  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 Institute nor the names of its contributors
 14 *    may be used to endorse or promote products derived from this software
 15 *    without specific prior written permission.
 16 *
 17 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 27 * SUCH DAMAGE.
 28 *
 29 * This file is part of the Contiki operating system.
 30 */
 31
 32/**
 33 * \file
 34 *         Implementation of the clock functions for the cc253x.
 35 *         Ported over from the cc243x original.
 36 * \author
 37 *         Zach Shelby (zach@sensinode.com) - original (cc243x)
 38 *         George Oikonomou - <oikonomou@users.sourceforge.net> - cc2530 port
 39 */
 40#include "sfr-bits.h"
 41#include "sys/clock.h"
 42#include "sys/etimer.h"
 43#include "cc253x.h"
 44#include "sys/energest.h"
 45
 46/* Sleep timer runs on the 32k RC osc. */
 47/* One clock tick is 7.8 ms */
 48#define TICK_VAL (32768/128)  /* 256 */
 49/*---------------------------------------------------------------------------*/
 50#if CLOCK_CONF_STACK_FRIENDLY
 51volatile uint8_t sleep_flag;
 52#endif
 53/*---------------------------------------------------------------------------*/
 54/* Do NOT remove the absolute address and do NOT remove the initialiser here */
 55__xdata __at(0x0000) static unsigned long timer_value = 0;
 56
 57static volatile CC_AT_DATA clock_time_t count = 0; /* Uptime in ticks */
 58static volatile CC_AT_DATA clock_time_t seconds = 0; /* Uptime in secs */
 59/*---------------------------------------------------------------------------*/
 60/**
 61 * Each iteration is ~1.0xy usec, so this function delays for roughly len usec
 62 */
 63void
 64clock_delay_usec(uint16_t len)
 65{
 66  DISABLE_INTERRUPTS();
 67  while(len--) {
 68    ASM(nop);
 69  }
 70  ENABLE_INTERRUPTS();
 71}
 72/*---------------------------------------------------------------------------*/
 73/**
 74 * Wait for a multiple of ~8 ms (a tick)
 75 */
 76void
 77clock_wait(clock_time_t i)
 78{
 79  clock_time_t start;
 80
 81  start = clock_time();
 82  while(clock_time() - start < (clock_time_t)i);
 83}
 84/*---------------------------------------------------------------------------*/
 85CCIF clock_time_t
 86clock_time(void)
 87{
 88  return count;
 89}
 90/*---------------------------------------------------------------------------*/
 91CCIF unsigned long
 92clock_seconds(void)
 93{
 94  return seconds;
 95}
 96/*---------------------------------------------------------------------------*/
 97/*
 98 * There is some ambiguity between TI cc2530 software examples and information
 99 * in the datasheet.
100 *
101 * TI examples appear to be writing to SLEEPCMD, initialising hardware in a
102 * fashion semi-similar to cc2430
103 *
104 * However, the datasheet claims that those bits in SLEEPCMD are reserved
105 *
106 * The code here goes by the datasheet (ignore TI examples) and seems to work.
107 */
108void
109clock_init(void)
110{
111  /* Make sure we know where we stand */
112  CLKCONCMD = CLKCONCMD_OSC32K | CLKCONCMD_OSC;
113
114  /* Stay with 32 KHz RC OSC, Chance System Clock to 32 MHz */
115  CLKCONCMD &= ~CLKCONCMD_OSC;
116  while(CLKCONSTA & CLKCONCMD_OSC);
117
118  /* Tickspeed 500 kHz for timers[1-4] */
119  CLKCONCMD |= CLKCONCMD_TICKSPD2 | CLKCONCMD_TICKSPD1;
120  while(CLKCONSTA != CLKCONCMD);
121
122  /* Initialize tick value */
123  timer_value = ST0;
124  timer_value += ((unsigned long int)ST1) << 8;
125  timer_value += ((unsigned long int)ST2) << 16;
126  timer_value += TICK_VAL;
127  ST2 = (unsigned char)(timer_value >> 16);
128  ST1 = (unsigned char)(timer_value >> 8);
129  ST0 = (unsigned char)timer_value;
130
131  STIE = 1; /* IEN0.STIE interrupt enable */
132}
133/*---------------------------------------------------------------------------*/
134/* avoid referencing bits, we don't call code which use them */
135#pragma save
136#if CC_CONF_OPTIMIZE_STACK_SIZE
137#pragma exclude bits
138#endif
139void
140clock_isr(void) __interrupt(ST_VECTOR)
141{
142  DISABLE_INTERRUPTS();
143  ENERGEST_ON(ENERGEST_TYPE_IRQ);
144
145  /*
146   * Read value of the ST0:ST1:ST2, add TICK_VAL and write it back.
147   * Next interrupt occurs after the current time + TICK_VAL
148   */
149  timer_value = ST0;
150  timer_value += ((unsigned long int)ST1) << 8;
151  timer_value += ((unsigned long int)ST2) << 16;
152  timer_value += TICK_VAL;
153  ST2 = (unsigned char)(timer_value >> 16);
154  ST1 = (unsigned char)(timer_value >> 8);
155  ST0 = (unsigned char)timer_value;
156
157  ++count;
158
159  /* Make sure the CLOCK_CONF_SECOND is a power of two, to ensure
160     that the modulo operation below becomes a logical and and not
161     an expensive divide. Algorithm from Wikipedia:
162     http://en.wikipedia.org/wiki/Power_of_two */
163#if (CLOCK_CONF_SECOND & (CLOCK_CONF_SECOND - 1)) != 0
164#error CLOCK_CONF_SECOND must be a power of two (i.e., 1, 2, 4, 8, 16, 32, 64, ...).
165#error Change CLOCK_CONF_SECOND in contiki-conf.h.
166#endif
167  if(count % CLOCK_CONF_SECOND == 0) {
168    ++seconds;
169  }
170
171#if CLOCK_CONF_STACK_FRIENDLY
172  sleep_flag = 1;
173#else
174  if(etimer_pending()
175      && (etimer_next_expiration_time() - count - 1) > MAX_TICKS) {
176    etimer_request_poll();
177  }
178#endif
179
180  STIF = 0; /* IRCON.STIF */
181  ENERGEST_OFF(ENERGEST_TYPE_IRQ);
182  ENABLE_INTERRUPTS();
183}
184#pragma restore
185/*---------------------------------------------------------------------------*/