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This library was superseded by mbed-dev - https://os.mbed.com/users/mbed_official/code/mbed-dev/.

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Last commit 20 Feb 2019 by mbed official

targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/us_ticker.c@526:7c4bdfe6a168, 2015-04-28 (annotated)

Committer:
mbed_official
Date:
Tue Apr 28 13:00:10 2015 +0100
Revision:
526:7c4bdfe6a168
Parent:
525:c320967f86b9
Child:
627:4fa1328d9c60
Synchronized with git revision cdff09e6b6c486eb58fb5e968f3191c8480b0567



Full URL: https://github.com/mbedmicro/mbed/commit/cdff09e6b6c486eb58fb5e968f3191c8480b0567/



Silabs - Fix unblock/block declaration, implement gpio_is_connected

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mbed_official 525:c320967f86b9 1 /* mbed Microcontroller Library
mbed_official 525:c320967f86b9 2 * Copyright (c) 2006-2013 ARM Limited
mbed_official 525:c320967f86b9 3 *
mbed_official 525:c320967f86b9 4 * Licensed under the Apache License, Version 2.0 (the "License");
mbed_official 525:c320967f86b9 5 * you may not use this file except in compliance with the License.
mbed_official 525:c320967f86b9 6 * You may obtain a copy of the License at
mbed_official 525:c320967f86b9 7 *
mbed_official 525:c320967f86b9 8 * http://www.apache.org/licenses/LICENSE-2.0
mbed_official 525:c320967f86b9 9 *
mbed_official 525:c320967f86b9 10 * Unless required by applicable law or agreed to in writing, software
mbed_official 525:c320967f86b9 11 * distributed under the License is distributed on an "AS IS" BASIS,
mbed_official 525:c320967f86b9 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
mbed_official 525:c320967f86b9 13 * See the License for the specific language governing permissions and
mbed_official 525:c320967f86b9 14 * limitations under the License.
mbed_official 525:c320967f86b9 15 */
mbed_official 525:c320967f86b9 16 #include <stddef.h>
mbed_official 525:c320967f86b9 17 #include "us_ticker_api.h"
mbed_official 525:c320967f86b9 18 #include "cmsis.h"
mbed_official 525:c320967f86b9 19 #include "mbed_assert.h"
mbed_official 525:c320967f86b9 20 #include "em_cmu.h"
mbed_official 525:c320967f86b9 21 #include "em_timer.h"
mbed_official 525:c320967f86b9 22 #include "device_peripherals.h"
mbed_official 525:c320967f86b9 23 #include "device.h"
mbed_official 525:c320967f86b9 24 #include "clocking.h"
mbed_official 525:c320967f86b9 25 #include "sleep_api.h"
mbed_official 526:7c4bdfe6a168 26 #include "sleepmodes.h"
mbed_official 525:c320967f86b9 27
mbed_official 525:c320967f86b9 28 #define TIMER_LEAST_ACTIVE_SLEEPMODE EM1
mbed_official 525:c320967f86b9 29 /**
mbed_official 525:c320967f86b9 30 * Timer functions for microsecond ticker.
mbed_official 525:c320967f86b9 31 * mbed expects a 32-bit timer. Since the EFM32 only has 16-bit timers,
mbed_official 525:c320967f86b9 32 * the upper 16 bits are implemented in software.
mbed_official 525:c320967f86b9 33 */
mbed_official 525:c320967f86b9 34
mbed_official 525:c320967f86b9 35 static uint8_t us_ticker_inited = 0; // Is ticker initialized yet
mbed_official 525:c320967f86b9 36
mbed_official 525:c320967f86b9 37 static volatile uint32_t ticker_cnt = 0x2ff00; //Internal overflow count, used to extend internal 16-bit counter to (MHz * 32-bit)
mbed_official 525:c320967f86b9 38 static volatile uint16_t ticker_int_rem = 0; //Timer match value for user interrupt
mbed_official 525:c320967f86b9 39 static volatile uint32_t ticker_int_cnt = 0; //Amount of overflows until user interrupt
mbed_official 525:c320967f86b9 40 static volatile uint8_t ticker_freq_mhz = 0; //Frequency of timer in MHz
mbed_official 525:c320967f86b9 41
mbed_official 525:c320967f86b9 42 void us_ticker_irq_handler_internal(void)
mbed_official 525:c320967f86b9 43 {
mbed_official 525:c320967f86b9 44 /* Check for user interrupt expiration */
mbed_official 525:c320967f86b9 45 if (TIMER_IntGet(US_TICKER_TIMER) & TIMER_IF_CC0) {
mbed_official 525:c320967f86b9 46 if (ticker_int_rem > 0) {
mbed_official 525:c320967f86b9 47 TIMER_CompareSet(US_TICKER_TIMER, 0, ticker_int_rem);
mbed_official 525:c320967f86b9 48 ticker_int_rem = 0;
mbed_official 525:c320967f86b9 49 TIMER_IntClear(US_TICKER_TIMER, TIMER_IF_CC0);
mbed_official 525:c320967f86b9 50 } else if (ticker_int_cnt > 0) {
mbed_official 525:c320967f86b9 51 ticker_int_cnt--;
mbed_official 525:c320967f86b9 52 TIMER_IntClear(US_TICKER_TIMER, TIMER_IF_CC0);
mbed_official 525:c320967f86b9 53 } else {
mbed_official 525:c320967f86b9 54 us_ticker_irq_handler();
mbed_official 525:c320967f86b9 55 }
mbed_official 525:c320967f86b9 56 }
mbed_official 525:c320967f86b9 57
mbed_official 525:c320967f86b9 58 /* Handle timer overflow */
mbed_official 525:c320967f86b9 59 if (TIMER_IntGet(US_TICKER_TIMER) & TIMER_IF_OF) {
mbed_official 525:c320967f86b9 60 ticker_cnt++;
mbed_official 525:c320967f86b9 61 if(ticker_cnt >= (((uint32_t)ticker_freq_mhz) << 16)) ticker_cnt = 0;
mbed_official 525:c320967f86b9 62 TIMER_IntClear(US_TICKER_TIMER, TIMER_IF_OF);
mbed_official 525:c320967f86b9 63 }
mbed_official 525:c320967f86b9 64 }
mbed_official 525:c320967f86b9 65
mbed_official 525:c320967f86b9 66 void us_ticker_init(void)
mbed_official 525:c320967f86b9 67 {
mbed_official 525:c320967f86b9 68 if (us_ticker_inited) {
mbed_official 525:c320967f86b9 69 return;
mbed_official 525:c320967f86b9 70 }
mbed_official 525:c320967f86b9 71 us_ticker_inited = 1;
mbed_official 525:c320967f86b9 72
mbed_official 525:c320967f86b9 73 /* Enable clock for TIMERs */
mbed_official 525:c320967f86b9 74 CMU_ClockEnable(US_TICKER_TIMER_CLOCK, true);
mbed_official 525:c320967f86b9 75
mbed_official 525:c320967f86b9 76 /* Clear TIMER counter value */
mbed_official 525:c320967f86b9 77 TIMER_CounterSet(US_TICKER_TIMER, 0);
mbed_official 525:c320967f86b9 78
mbed_official 525:c320967f86b9 79 /* Get frequency of clock in MHz for scaling ticks to microseconds */
mbed_official 525:c320967f86b9 80 ticker_freq_mhz = (REFERENCE_FREQUENCY / 1000000);
mbed_official 525:c320967f86b9 81 MBED_ASSERT(ticker_freq_mhz > 0);
mbed_official 525:c320967f86b9 82
mbed_official 525:c320967f86b9 83 /*
mbed_official 525:c320967f86b9 84 * Calculate maximum prescaler that gives at least 1 MHz frequency, while keeping clock as an integer multiple of 1 MHz.
mbed_official 525:c320967f86b9 85 * Example: 14 MHz => prescaler = 1 (i.e. DIV2), ticker_freq_mhz = 7;
mbed_official 525:c320967f86b9 86 * 24 MHz => prescaler = 3 (i.e. DIV8), ticker_freq_mhz = 3;
mbed_official 525:c320967f86b9 87 * 48 MHz => prescaler = 4 (i.e. DIV16), ticker_freq_mhz = 3;
mbed_official 525:c320967f86b9 88 * Limit prescaling to maximum prescaler value, which is 10 (DIV1024).
mbed_official 525:c320967f86b9 89 */
mbed_official 525:c320967f86b9 90 uint32_t prescaler = 0;
mbed_official 525:c320967f86b9 91 while((ticker_freq_mhz & 1) == 0 && prescaler <= 10) {
mbed_official 525:c320967f86b9 92 ticker_freq_mhz = ticker_freq_mhz >> 1;
mbed_official 525:c320967f86b9 93 prescaler++;
mbed_official 525:c320967f86b9 94 }
mbed_official 525:c320967f86b9 95
mbed_official 525:c320967f86b9 96 /* Set prescaler */
mbed_official 525:c320967f86b9 97 US_TICKER_TIMER->CTRL = (US_TICKER_TIMER->CTRL & ~_TIMER_CTRL_PRESC_MASK) | (prescaler << _TIMER_CTRL_PRESC_SHIFT);
mbed_official 525:c320967f86b9 98
mbed_official 525:c320967f86b9 99 /* Select Compare Channel parameters */
mbed_official 525:c320967f86b9 100 TIMER_InitCC_TypeDef timerCCInit = TIMER_INITCC_DEFAULT;
mbed_official 525:c320967f86b9 101 timerCCInit.mode = timerCCModeCompare;
mbed_official 525:c320967f86b9 102
mbed_official 525:c320967f86b9 103 /* Configure Compare Channel 0 */
mbed_official 525:c320967f86b9 104 TIMER_InitCC(US_TICKER_TIMER, 0, &timerCCInit);
mbed_official 525:c320967f86b9 105
mbed_official 525:c320967f86b9 106 /* Enable interrupt vector in NVIC */
mbed_official 525:c320967f86b9 107 TIMER_IntEnable(US_TICKER_TIMER, TIMER_IEN_OF);
mbed_official 525:c320967f86b9 108 NVIC_SetVector(US_TICKER_TIMER_IRQ, (uint32_t) us_ticker_irq_handler_internal);
mbed_official 525:c320967f86b9 109 NVIC_EnableIRQ(US_TICKER_TIMER_IRQ);
mbed_official 525:c320967f86b9 110
mbed_official 525:c320967f86b9 111 /* Set top value */
mbed_official 525:c320967f86b9 112 TIMER_TopSet(US_TICKER_TIMER, 0xFFFF);
mbed_official 525:c320967f86b9 113
mbed_official 525:c320967f86b9 114 /* Start TIMER */
mbed_official 525:c320967f86b9 115 TIMER_Enable(US_TICKER_TIMER, true);
mbed_official 525:c320967f86b9 116 }
mbed_official 525:c320967f86b9 117
mbed_official 525:c320967f86b9 118 uint32_t us_ticker_read()
mbed_official 525:c320967f86b9 119 {
mbed_official 525:c320967f86b9 120 uint32_t volatile countH_old, countH, countL;
mbed_official 525:c320967f86b9 121
mbed_official 525:c320967f86b9 122 if (!us_ticker_inited) {
mbed_official 525:c320967f86b9 123 us_ticker_init();
mbed_official 525:c320967f86b9 124 }
mbed_official 525:c320967f86b9 125
mbed_official 525:c320967f86b9 126 /* Avoid jumping in time by reading high bits twice */
mbed_official 525:c320967f86b9 127 do {
mbed_official 525:c320967f86b9 128 countH_old = ticker_cnt;
mbed_official 525:c320967f86b9 129 /* If the counter overflowed while in the IRQ handler for the CC0 interrupt,
mbed_official 525:c320967f86b9 130 * it hasn't had time to update ticker_cnt yet. Take this into account here. */
mbed_official 525:c320967f86b9 131 if (TIMER_IntGet(US_TICKER_TIMER) & TIMER_IF_OF) {
mbed_official 525:c320967f86b9 132 countH_old += 1;
mbed_official 525:c320967f86b9 133 }
mbed_official 525:c320967f86b9 134 countL = US_TICKER_TIMER->CNT;
mbed_official 525:c320967f86b9 135 countH = ticker_cnt;
mbed_official 525:c320967f86b9 136 /* If the counter overflowed while in the IRQ handler for the CC0 interrupt,
mbed_official 525:c320967f86b9 137 * it hasn't had time to update ticker_cnt yet. Take this into account here. */
mbed_official 525:c320967f86b9 138 if (TIMER_IntGet(US_TICKER_TIMER) & TIMER_IF_OF) {
mbed_official 525:c320967f86b9 139 countH += 1;
mbed_official 525:c320967f86b9 140 }
mbed_official 525:c320967f86b9 141 } while (countH_old != countH);
mbed_official 525:c320967f86b9 142
mbed_official 525:c320967f86b9 143 /* Merge upper (mhz * 16-bit) and lower 16-bit into 64bit */
mbed_official 525:c320967f86b9 144 uint64_t count = ((uint64_t)countH << 16) | (uint64_t)countL;
mbed_official 525:c320967f86b9 145 /* Divide by ticker_freq_mhz to get 32-bit 1MHz timestamp */
mbed_official 525:c320967f86b9 146 return (count / ticker_freq_mhz);
mbed_official 525:c320967f86b9 147 }
mbed_official 525:c320967f86b9 148
mbed_official 525:c320967f86b9 149 void us_ticker_set_interrupt(timestamp_t timestamp)
mbed_official 525:c320967f86b9 150 {
mbed_official 525:c320967f86b9 151 int32_t delta = 0, ts = timestamp, time = us_ticker_read();
mbed_official 525:c320967f86b9 152
mbed_official 525:c320967f86b9 153 if((US_TICKER_TIMER->IEN & TIMER_IEN_CC0) == 0) {
mbed_official 525:c320967f86b9 154 //Timer was disabled, but is going to be enabled. Set sleep mode.
mbed_official 525:c320967f86b9 155 blockSleepMode(TIMER_LEAST_ACTIVE_SLEEPMODE);
mbed_official 525:c320967f86b9 156 }
mbed_official 525:c320967f86b9 157 TIMER_IntDisable(US_TICKER_TIMER, TIMER_IEN_CC0);
mbed_official 525:c320967f86b9 158
mbed_official 525:c320967f86b9 159 delta = ts - time;
mbed_official 525:c320967f86b9 160 if(delta <= ticker_freq_mhz) {
mbed_official 525:c320967f86b9 161 delta = ticker_freq_mhz;
mbed_official 525:c320967f86b9 162 timestamp = us_ticker_read() + 0x100;
mbed_official 525:c320967f86b9 163 }
mbed_official 525:c320967f86b9 164
mbed_official 525:c320967f86b9 165 /* Multiply by ticker_freq_mhz to get clock ticks */
mbed_official 525:c320967f86b9 166 delta *= ticker_freq_mhz;
mbed_official 525:c320967f86b9 167 /* Overflowing this doesn't matter, since we only need the lower 16 bits */
mbed_official 525:c320967f86b9 168 ts *= ticker_freq_mhz;
mbed_official 525:c320967f86b9 169
mbed_official 525:c320967f86b9 170 /* Split delta between timers */
mbed_official 525:c320967f86b9 171 ticker_int_cnt = (((uint64_t)delta) >> 16) & 0xFFFFFFFF;
mbed_official 525:c320967f86b9 172 ticker_int_rem = ts & 0xFFFF;
mbed_official 525:c320967f86b9 173
mbed_official 525:c320967f86b9 174 /* Set compare channel 0 to (current position + lower 16 bits of delta).
mbed_official 525:c320967f86b9 175 * If lower 16 bits is a small number, we a do one compare of (current + lower 16 + 0x8000)
mbed_official 525:c320967f86b9 176 * and then one of (current + lower 16). Else, we simply use (current + lower 16).
mbed_official 525:c320967f86b9 177 *
mbed_official 525:c320967f86b9 178 * When time from lower 16 bits have elapsed, run complete cycles with ticker_int_rem as
mbed_official 525:c320967f86b9 179 * reference ticker_int_cnt times. */
mbed_official 525:c320967f86b9 180 if ((delta & 0xFFFF) < 0x8000 && ticker_int_cnt > 0) {
mbed_official 525:c320967f86b9 181 TIMER_CompareSet(US_TICKER_TIMER, 0, ticker_int_rem + 0x8000);
mbed_official 525:c320967f86b9 182 ticker_int_cnt--;
mbed_official 525:c320967f86b9 183 } else {
mbed_official 525:c320967f86b9 184 TIMER_CompareSet(US_TICKER_TIMER, 0, ticker_int_rem);
mbed_official 525:c320967f86b9 185 ticker_int_rem = 0;
mbed_official 525:c320967f86b9 186 }
mbed_official 525:c320967f86b9 187 TIMER_IntClear(US_TICKER_TIMER, TIMER_IFC_CC0);
mbed_official 525:c320967f86b9 188 TIMER_IntEnable(US_TICKER_TIMER, TIMER_IEN_CC0);
mbed_official 525:c320967f86b9 189 }
mbed_official 525:c320967f86b9 190
mbed_official 525:c320967f86b9 191 void us_ticker_disable_interrupt(void)
mbed_official 525:c320967f86b9 192 {
mbed_official 525:c320967f86b9 193 if((US_TICKER_TIMER->IEN & TIMER_IEN_CC0) != 0) {
mbed_official 525:c320967f86b9 194 //Timer was enabled, but is going to get disabled. Clear sleepmode.
mbed_official 525:c320967f86b9 195 unblockSleepMode(TIMER_LEAST_ACTIVE_SLEEPMODE);
mbed_official 525:c320967f86b9 196 }
mbed_official 525:c320967f86b9 197 /* Disable compare channel interrupts */
mbed_official 525:c320967f86b9 198 TIMER_IntDisable(US_TICKER_TIMER, TIMER_IEN_CC0);
mbed_official 525:c320967f86b9 199 }
mbed_official 525:c320967f86b9 200
mbed_official 525:c320967f86b9 201 void us_ticker_clear_interrupt(void)
mbed_official 525:c320967f86b9 202 {
mbed_official 525:c320967f86b9 203 /* Clear compare channel interrupts */
mbed_official 525:c320967f86b9 204 TIMER_IntClear(US_TICKER_TIMER, TIMER_IFC_CC0);
mbed_official 525:c320967f86b9 205 }