/* mbed Microcontroller Library * Copyright (c) 2016 ARM Limited * * 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. */ #if DEVICE_LPTICKER #include "lp_ticker_api.h" #include "fsl_snvs_hp.h" #include "fsl_gpt.h" #include "cmsis.h" #include "rtc_api.h" #define LOWFREQ_REF_CLK_HZ (32768) static bool lp_ticker_inited = false; static void gpt_isr(void) { GPT_ClearStatusFlags(GPT2, kGPT_OutputCompare1Flag); GPT_StopTimer(GPT2); lp_ticker_irq_handler(); } /** Initialize the low power ticker * */ void lp_ticker_init(void) { gpt_config_t gptConfig; if (lp_ticker_inited) { return; } lp_ticker_inited = true; /* Setup low resolution clock - RTC */ if (!rtc_isenabled()) { rtc_init(); } /* Setup GPT */ GPT_GetDefaultConfig(&gptConfig); /* Use 32kHz drive */ gptConfig.clockSource = kGPT_ClockSource_LowFreq; GPT_Init(GPT2, &gptConfig); GPT_EnableInterrupts(GPT2, kGPT_OutputCompare1InterruptEnable); NVIC_ClearPendingIRQ(GPT2_IRQn); NVIC_SetVector(GPT2_IRQn, (uint32_t)gpt_isr); EnableIRQ(GPT2_IRQn); } /** Read the current counter * * @return The current timer's counter value in microseconds */ uint32_t lp_ticker_read(void) { uint32_t ticks = 0; uint64_t tmp = 0; if (!lp_ticker_inited) { lp_ticker_init(); } /* Do consecutive reads until value is correct */ do { ticks = tmp; tmp = SNVS->HPRTCLR; } while (tmp != ticks); return COUNT_TO_USEC(ticks, LOWFREQ_REF_CLK_HZ);; } /** Set interrupt for specified timestamp * * @param timestamp The time in microseconds to be set */ void lp_ticker_set_interrupt(timestamp_t timestamp) { uint32_t now_us, delta_us, delta_ticks; if (!lp_ticker_inited) { lp_ticker_init(); } now_us = lp_ticker_read(); delta_us = timestamp > now_us ? timestamp - now_us : (uint32_t)((uint64_t)timestamp + 0xFFFFFFFF - now_us); delta_ticks = USEC_TO_COUNT(delta_us, LOWFREQ_REF_CLK_HZ); if (delta_ticks == 0) { delta_ticks = 1; } GPT_SetOutputCompareValue(GPT2, kGPT_OutputCompare_Channel1, delta_ticks); GPT_EnableInterrupts(GPT2, kGPT_OutputCompare1InterruptEnable); GPT_StartTimer(GPT2); } void lp_ticker_fire_interrupt(void) { NVIC_SetPendingIRQ(GPT2_IRQn); } /** Disable low power ticker interrupt * */ void lp_ticker_disable_interrupt(void) { GPT_DisableInterrupts(GPT2, kGPT_OutputCompare1InterruptEnable); } /** Clear the low power ticker interrupt * */ void lp_ticker_clear_interrupt(void) { GPT_ClearStatusFlags(GPT2, kGPT_OutputCompare1Flag); } #endif /* DEVICE_LPTICKER */