lp_ticker_api.h

00001 
00002 /** \addtogroup hal */
00003 /** @{*/
00004 /* mbed Microcontroller Library
00005  * Copyright (c) 2015 ARM Limited
00006  * SPDX-License-Identifier: Apache-2.0
00007  *
00008  * Licensed under the Apache License, Version 2.0 (the "License");
00009  * you may not use this file except in compliance with the License.
00010  * You may obtain a copy of the License at
00011  *
00012  *     http://www.apache.org/licenses/LICENSE-2.0
00013  *
00014  * Unless required by applicable law or agreed to in writing, software
00015  * distributed under the License is distributed on an "AS IS" BASIS,
00016  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00017  * See the License for the specific language governing permissions and
00018  * limitations under the License.
00019  */
00020 #ifndef MBED_LPTICKER_API_H
00021 #define MBED_LPTICKER_API_H
00022 
00023 #include "device.h"
00024 
00025 #if DEVICE_LPTICKER
00026 
00027 #include "hal/ticker_api.h"
00028 
00029 #ifdef __cplusplus
00030 extern "C" {
00031 #endif
00032 
00033 /**
00034  * \defgroup hal_lp_ticker Low Power Ticker
00035  * Low level interface to the low power ticker of a target
00036  *
00037  * # Defined behavior
00038  * * Has a reported frequency between 4KHz and 64KHz - verified by ::lp_ticker_info_test
00039  * * Has a counter that is at least 12 bits wide - verified by ::lp_ticker_info_test
00040  * * Continues operating in deep sleep mode - verified by ::lp_ticker_deepsleep_test
00041  * * All behavior defined by the @ref hal_ticker_shared "ticker specification"
00042  *
00043  * # Undefined behavior
00044  * * See the @ref hal_ticker_shared "ticker specification"
00045  * * Calling any function other than lp_ticker_init after calling lp_ticker_free
00046  *
00047  * # Potential bugs
00048  * * Glitches due to ripple counter - Verified by ::lp_ticker_glitch_test
00049  *
00050  * @see hal_lp_ticker_tests
00051  *
00052  * @{
00053  */
00054 
00055 /**
00056  * \defgroup hal_lp_ticker_tests Low Power Ticker tests
00057  * Tests to validate the proper implementation of the low power ticker
00058  *
00059  * To run the low power ticker hal tests use the command:
00060  *
00061  *     mbed test -t <toolchain> -m <target> -n tests-mbed_hal-common_ticker*,tests-mbed_hal-lp_ticker*
00062  *
00063  */
00064 
00065 typedef void (*ticker_irq_handler_type)(const ticker_data_t *const);
00066 
00067 /** Set low power ticker IRQ handler
00068  *
00069  * @param ticker_irq_handler IRQ handler to be connected
00070  *
00071  * @return previous ticker IRQ handler
00072  *
00073  * @note by default IRQ handler is set to ::ticker_irq_handler
00074  * @note this function is primarily for testing purposes and it's not required part of HAL implementation
00075  *
00076  */
00077 ticker_irq_handler_type set_lp_ticker_irq_handler(ticker_irq_handler_type ticker_irq_handler);
00078 
00079 /** Get low power ticker's data
00080  *
00081  * @return The low power ticker data
00082  */
00083 const ticker_data_t *get_lp_ticker_data(void);
00084 
00085 /** The wrapper for ticker_irq_handler, to pass lp ticker's data
00086  *
00087  */
00088 void lp_ticker_irq_handler(void);
00089 
00090 /* HAL lp ticker */
00091 
00092 /** Initialize the low power ticker
00093  *
00094  * Initialize or re-initialize the ticker. This resets all the
00095  * clocking and prescaler registers, along with disabling
00096  * the compare interrupt.
00097  *
00098  * Pseudo Code:
00099  * @code
00100  * void lp_ticker_init()
00101  * {
00102  *     // Enable clock gate so processor can read LPTMR registers
00103  *     POWER_CTRL |= POWER_CTRL_LPTMR_Msk;
00104  *
00105  *     // Disable the timer and ensure it is powered down
00106  *     LPTMR_CTRL &= ~(LPTMR_CTRL_ENABLE_Msk | LPTMR_CTRL_COMPARE_ENABLE_Msk);
00107  *
00108  *     // Configure divisors - no division necessary
00109  *     LPTMR_PRESCALE = 0;
00110  *     LPTMR_CTRL |= LPTMR_CTRL_ENABLE_Msk;
00111  *
00112  *     // Install the interrupt handler
00113  *     NVIC_SetVector(LPTMR_IRQn, (uint32_t)lp_ticker_irq_handler);
00114  *     NVIC_EnableIRQ(LPTMR_IRQn);
00115  * }
00116  * @endcode
00117  */
00118 void lp_ticker_init(void);
00119 
00120 /** Deinitialize the lower power ticker
00121  *
00122  * Powerdown the lp ticker in preparation for sleep, powerdown, or reset.
00123  *
00124  * After calling this function no other ticker functions should be called except
00125  * lp_ticker_init(). Calling any function other than init after freeing is
00126  * undefined.
00127  *
00128  * @note This function stops the ticker from counting.
00129  */
00130 void lp_ticker_free(void);
00131 
00132 /** Read the current tick
00133  *
00134  * If no rollover has occurred, the seconds passed since lp_ticker_init()
00135  * was called can be found by dividing the ticks returned by this function
00136  * by the frequency returned by ::lp_ticker_get_info.
00137  *
00138  * @return The current timer's counter value in ticks
00139  *
00140  * Pseudo Code:
00141  * @code
00142  * uint32_t lp_ticker_read()
00143  * {
00144  *     uint16_t count;
00145  *     uint16_t last_count;
00146  *
00147  *     // Loop until the same tick is read twice since this
00148  *     // is ripple counter on a different clock domain.
00149  *     count = LPTMR_COUNT;
00150  *     do {
00151  *         last_count = count;
00152  *         count = LPTMR_COUNT;
00153  *     } while (last_count != count);
00154  *
00155  *     return count;
00156  * }
00157  * @endcode
00158  */
00159 uint32_t lp_ticker_read(void);
00160 
00161 /** Set interrupt for specified timestamp
00162  *
00163  * @param timestamp The time in ticks to be set
00164  *
00165  * @note no special handling needs to be done for times in the past
00166  * as the common timer code will detect this and call
00167  * lp_ticker_fire_interrupt() if this is the case
00168  *
00169  * @note calling this function with timestamp of more than the supported
00170  * number of bits returned by ::lp_ticker_get_info results in undefined
00171  * behavior.
00172  *
00173  * Pseudo Code:
00174  * @code
00175  * void lp_ticker_set_interrupt(timestamp_t timestamp)
00176  * {
00177  *     LPTMR_COMPARE = timestamp;
00178  *     LPTMR_CTRL |= LPTMR_CTRL_COMPARE_ENABLE_Msk;
00179  * }
00180  * @endcode
00181  */
00182 void lp_ticker_set_interrupt(timestamp_t timestamp);
00183 
00184 /** Disable low power ticker interrupt
00185  *
00186  * Pseudo Code:
00187  * @code
00188  * void lp_ticker_disable_interrupt(void)
00189  * {
00190  *     // Disable the compare interrupt
00191  *     LPTMR_CTRL &= ~LPTMR_CTRL_COMPARE_ENABLE_Msk;
00192  * }
00193  * @endcode
00194  */
00195 void lp_ticker_disable_interrupt(void);
00196 
00197 /** Clear the low power ticker interrupt
00198  *
00199  * Pseudo Code:
00200  * @code
00201  * void lp_ticker_clear_interrupt(void)
00202  * {
00203  *     // Write to the ICR (interrupt clear register) of the LPTMR
00204  *     LPTMR_ICR = LPTMR_ICR_COMPARE_Msk;
00205  * }
00206  * @endcode
00207  */
00208 void lp_ticker_clear_interrupt(void);
00209 
00210 /** Set pending interrupt that should be fired right away.
00211  *
00212  * Pseudo Code:
00213  * @code
00214  * void lp_ticker_fire_interrupt(void)
00215  * {
00216  *     NVIC_SetPendingIRQ(LPTMR_IRQn);
00217  * }
00218  * @endcode
00219  */
00220 void lp_ticker_fire_interrupt(void);
00221 
00222 /** Get frequency and counter bits of this ticker.
00223  *
00224  * Pseudo Code:
00225  * @code
00226  * const ticker_info_t* lp_ticker_get_info()
00227  * {
00228  *     static const ticker_info_t info = {
00229  *         32768,      // 32KHz
00230  *         16          // 16 bit counter
00231  *     };
00232  *     return &info;
00233  * }
00234  * @endcode
00235  */
00236 const ticker_info_t *lp_ticker_get_info(void);
00237 
00238 /**@}*/
00239 
00240 #ifdef __cplusplus
00241 }
00242 #endif
00243 
00244 #endif
00245 
00246 #endif
00247 
00248 /** @}*/