Johannes Stratmann / mbed-dev

added prescaler for 16 bit pwm in LPC1347 target

Fork of mbed-dev by mbed official

targets/hal/TARGET_Freescale/TARGET_KSDK2_MCUS/TARGET_KL27Z/us_ticker.c@147:ba84b7dc41a7, 2016-09-10 (annotated)

Committer:
JojoS
Date:
Sat Sep 10 15:32:04 2016 +0000
Revision:
147:ba84b7dc41a7
Parent:
121:7f86b4238bec 
added prescaler for 16 bit timers (solution as in LPC11xx), default prescaler 31 for max 28 ms period time

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mbed_official 121:7f86b4238bec 1 /* mbed Microcontroller Library
mbed_official 121:7f86b4238bec 2 * Copyright (c) 2006-2013 ARM Limited
mbed_official 121:7f86b4238bec 3 *
mbed_official 121:7f86b4238bec 4 * Licensed under the Apache License, Version 2.0 (the "License");
mbed_official 121:7f86b4238bec 5 * you may not use this file except in compliance with the License.
mbed_official 121:7f86b4238bec 6 * You may obtain a copy of the License at
mbed_official 121:7f86b4238bec 7 *
mbed_official 121:7f86b4238bec 8 * http://www.apache.org/licenses/LICENSE-2.0
mbed_official 121:7f86b4238bec 9 *
mbed_official 121:7f86b4238bec 10 * Unless required by applicable law or agreed to in writing, software
mbed_official 121:7f86b4238bec 11 * distributed under the License is distributed on an "AS IS" BASIS,
mbed_official 121:7f86b4238bec 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
mbed_official 121:7f86b4238bec 13 * See the License for the specific language governing permissions and
mbed_official 121:7f86b4238bec 14 * limitations under the License.
mbed_official 121:7f86b4238bec 15 */
mbed_official 121:7f86b4238bec 16 #include <stddef.h>
mbed_official 121:7f86b4238bec 17 #include "us_ticker_api.h"
mbed_official 121:7f86b4238bec 18 #include "PeripheralNames.h"
mbed_official 121:7f86b4238bec 19 #include "fsl_pit.h"
mbed_official 121:7f86b4238bec 20 #include "fsl_lptmr.h"
mbed_official 121:7f86b4238bec 21 #include "fsl_clock_config.h"
mbed_official 121:7f86b4238bec 22
mbed_official 121:7f86b4238bec 23 static int us_ticker_inited = 0;
mbed_official 121:7f86b4238bec 24
mbed_official 121:7f86b4238bec 25 void us_ticker_init(void) {
mbed_official 121:7f86b4238bec 26 if (us_ticker_inited) {
mbed_official 121:7f86b4238bec 27 return;
mbed_official 121:7f86b4238bec 28 }
mbed_official 121:7f86b4238bec 29 us_ticker_inited = 1;
mbed_official 121:7f86b4238bec 30
mbed_official 121:7f86b4238bec 31 // Need to initialize the clocks here as ticker init gets called before mbed_sdk_init
mbed_official 121:7f86b4238bec 32 if (SystemCoreClock == DEFAULT_SYSTEM_CLOCK)
mbed_official 121:7f86b4238bec 33 BOARD_BootClockRUN();
mbed_official 121:7f86b4238bec 34
mbed_official 121:7f86b4238bec 35 //Timer uses PIT
mbed_official 121:7f86b4238bec 36 //Common for ticker/timer
mbed_official 121:7f86b4238bec 37 uint32_t busClock;
mbed_official 121:7f86b4238bec 38
mbed_official 121:7f86b4238bec 39 // Structure to initialize PIT
mbed_official 121:7f86b4238bec 40 pit_config_t pitConfig;
mbed_official 121:7f86b4238bec 41
mbed_official 121:7f86b4238bec 42 PIT_GetDefaultConfig(&pitConfig);
mbed_official 121:7f86b4238bec 43 PIT_Init(PIT, &pitConfig);
mbed_official 121:7f86b4238bec 44
mbed_official 121:7f86b4238bec 45 busClock = CLOCK_GetFreq(kCLOCK_BusClk);
mbed_official 121:7f86b4238bec 46
mbed_official 121:7f86b4238bec 47 PIT_SetTimerPeriod(PIT, kPIT_Chnl_0, busClock / 1000000 - 1);
mbed_official 121:7f86b4238bec 48 PIT_SetTimerPeriod(PIT, kPIT_Chnl_1, 0xFFFFFFFF);
mbed_official 121:7f86b4238bec 49 PIT_SetTimerChainMode(PIT, kPIT_Chnl_1, true);
mbed_official 121:7f86b4238bec 50 PIT_StartTimer(PIT, kPIT_Chnl_0);
mbed_official 121:7f86b4238bec 51 PIT_StartTimer(PIT, kPIT_Chnl_1);
mbed_official 121:7f86b4238bec 52
mbed_official 121:7f86b4238bec 53 //Ticker uses LPTMR
mbed_official 121:7f86b4238bec 54 lptmr_config_t lptmrConfig;
mbed_official 121:7f86b4238bec 55 LPTMR_GetDefaultConfig(&lptmrConfig);
mbed_official 121:7f86b4238bec 56 lptmrConfig.prescalerClockSource = kLPTMR_PrescalerClock_0;
mbed_official 121:7f86b4238bec 57 LPTMR_Init(LPTMR0, &lptmrConfig);
mbed_official 121:7f86b4238bec 58
mbed_official 121:7f86b4238bec 59 busClock = CLOCK_GetFreq(kCLOCK_McgInternalRefClk);
mbed_official 121:7f86b4238bec 60 LPTMR_SetTimerPeriod(LPTMR0, busClock / 1000000 - 1);
mbed_official 121:7f86b4238bec 61 /* Set interrupt handler */
mbed_official 121:7f86b4238bec 62 NVIC_SetVector(LPTMR0_IRQn, (uint32_t)us_ticker_irq_handler);
mbed_official 121:7f86b4238bec 63 NVIC_EnableIRQ(LPTMR0_IRQn);
mbed_official 121:7f86b4238bec 64 }
mbed_official 121:7f86b4238bec 65
mbed_official 121:7f86b4238bec 66
mbed_official 121:7f86b4238bec 67 uint32_t us_ticker_read() {
mbed_official 121:7f86b4238bec 68 if (!us_ticker_inited) {
mbed_official 121:7f86b4238bec 69 us_ticker_init();
mbed_official 121:7f86b4238bec 70 }
mbed_official 121:7f86b4238bec 71
mbed_official 121:7f86b4238bec 72 return ~(PIT_GetCurrentTimerCount(PIT, kPIT_Chnl_1));
mbed_official 121:7f86b4238bec 73 }
mbed_official 121:7f86b4238bec 74
mbed_official 121:7f86b4238bec 75 void us_ticker_disable_interrupt(void) {
mbed_official 121:7f86b4238bec 76 LPTMR_DisableInterrupts(LPTMR0, kLPTMR_TimerInterruptEnable);
mbed_official 121:7f86b4238bec 77 }
mbed_official 121:7f86b4238bec 78
mbed_official 121:7f86b4238bec 79 void us_ticker_clear_interrupt(void) {
mbed_official 121:7f86b4238bec 80 LPTMR_ClearStatusFlags(LPTMR0, kLPTMR_TimerCompareFlag);
mbed_official 121:7f86b4238bec 81 }
mbed_official 121:7f86b4238bec 82
mbed_official 121:7f86b4238bec 83 void us_ticker_set_interrupt(timestamp_t timestamp) {
mbed_official 121:7f86b4238bec 84 int delta = (int)(timestamp - us_ticker_read());
mbed_official 121:7f86b4238bec 85 if (delta <= 0) {
mbed_official 121:7f86b4238bec 86 // This event was in the past.
mbed_official 121:7f86b4238bec 87 // Set the interrupt as pending, but don't process it here.
mbed_official 121:7f86b4238bec 88 // This prevents a recurive loop under heavy load
mbed_official 121:7f86b4238bec 89 // which can lead to a stack overflow.
mbed_official 121:7f86b4238bec 90 NVIC_SetPendingIRQ(LPTMR0_IRQn);
mbed_official 121:7f86b4238bec 91 return;
mbed_official 121:7f86b4238bec 92 }
mbed_official 121:7f86b4238bec 93
mbed_official 121:7f86b4238bec 94 LPTMR_StopTimer(LPTMR0);
mbed_official 121:7f86b4238bec 95 LPTMR_SetTimerPeriod(LPTMR0, (uint32_t)delta);
mbed_official 121:7f86b4238bec 96 LPTMR_EnableInterrupts(LPTMR0, kLPTMR_TimerInterruptEnable);
mbed_official 121:7f86b4238bec 97 LPTMR_StartTimer(LPTMR0);
mbed_official 121:7f86b4238bec 98 }