/* mbed Microcontroller Library * Copyright (c) 2006-2018 ARM Limited * SPDX-License-Identifier: Apache-2.0 * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #include <stddef.h> #include "us_ticker_api.h" #include "us_ticker_defines.h" #include "fsl_pit.h" #include "clock_config.h" const ticker_info_t* us_ticker_get_info() { static const ticker_info_t info = { 1000000, // 1 MHz 32 // 32 bit counter }; return &info; } static bool us_ticker_inited = false; extern uint32_t us_ticker_get_clock(); static void pit_isr(void) { PIT_ClearStatusFlags(PIT, kPIT_Chnl_3, PIT_TFLG_TIF_MASK); PIT_ClearStatusFlags(PIT, kPIT_Chnl_2, PIT_TFLG_TIF_MASK); PIT_StopTimer(PIT, kPIT_Chnl_2); PIT_StopTimer(PIT, kPIT_Chnl_3); us_ticker_irq_handler(); } /** Initialize the high frequency ticker * */ void us_ticker_init(void) { /* Common for ticker/timer. */ uint32_t busClock; busClock = us_ticker_get_clock(); /* Let the timer to count if re-init. */ if (!us_ticker_inited) { /* Structure to initialize PIT. */ pit_config_t pitConfig; PIT_GetDefaultConfig(&pitConfig); PIT_Init(PIT, &pitConfig); PIT_SetTimerPeriod(PIT, kPIT_Chnl_0, busClock / 1000000 - 1); PIT_SetTimerPeriod(PIT, kPIT_Chnl_1, 0xFFFFFFFF); PIT_SetTimerChainMode(PIT, kPIT_Chnl_1, true); PIT_StartTimer(PIT, kPIT_Chnl_0); PIT_StartTimer(PIT, kPIT_Chnl_1); } /* Configure interrupt generation counters and disable ticker interrupts. */ PIT_StopTimer(PIT, kPIT_Chnl_3); PIT_StopTimer(PIT, kPIT_Chnl_2); PIT_SetTimerPeriod(PIT, kPIT_Chnl_2, busClock / 1000000 - 1); PIT_SetTimerChainMode(PIT, kPIT_Chnl_3, true); NVIC_SetVector(PIT_IRQn, (uint32_t) pit_isr); NVIC_EnableIRQ(PIT_IRQn); PIT_DisableInterrupts(PIT, kPIT_Chnl_3, kPIT_TimerInterruptEnable); us_ticker_inited = true; } /** Read the current counter * * @return The current timer's counter value in ticks */ uint32_t (us_ticker_read)() { return us_ticker_read(); } /** Disable us ticker interrupt * */ void us_ticker_disable_interrupt(void) { PIT_DisableInterrupts(PIT, kPIT_Chnl_3, kPIT_TimerInterruptEnable); } /** Clear us ticker interrupt * */ void us_ticker_clear_interrupt(void) { PIT_ClearStatusFlags(PIT, kPIT_Chnl_3, PIT_TFLG_TIF_MASK); } /** Set interrupt for specified timestamp * * @param timestamp The time in ticks when interrupt should be generated */ void us_ticker_set_interrupt(timestamp_t timestamp) { /* We get here absolute interrupt time which takes into account counter overflow. * Since we use additional count-down timer to generate interrupt we need to calculate * load value based on time-stamp. */ const uint32_t now_ticks = us_ticker_read(); uint32_t delta_ticks = timestamp >= now_ticks ? timestamp - now_ticks : (uint32_t)((uint64_t) timestamp + 0xFFFFFFFF - now_ticks); if (delta_ticks == 0) { /* The requested delay is less than the minimum resolution of this counter. */ delta_ticks = 1; } PIT_StopTimer(PIT, kPIT_Chnl_3); PIT_StopTimer(PIT, kPIT_Chnl_2); PIT_SetTimerPeriod(PIT, kPIT_Chnl_3, delta_ticks); PIT_EnableInterrupts(PIT, kPIT_Chnl_3, kPIT_TimerInterruptEnable); PIT_StartTimer(PIT, kPIT_Chnl_3); PIT_StartTimer(PIT, kPIT_Chnl_2); } /** Fire us ticker interrupt * */ void us_ticker_fire_interrupt(void) { NVIC_SetPendingIRQ(PIT_IRQn); } void us_ticker_free(void) { }