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_KL43Z/us_ticker.c@147:ba84b7dc41a7, 2016-09-10 (annotated)

Committer:
JojoS
Date:
Sat Sep 10 15:32:04 2016 +0000
Revision:
147:ba84b7dc41a7
Parent:
144:ef7eb2e8f9f7 
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
<> 144:ef7eb2e8f9f7 1 /* mbed Microcontroller Library
<> 144:ef7eb2e8f9f7 2 * Copyright (c) 2006-2013 ARM Limited
<> 144:ef7eb2e8f9f7 3 *
<> 144:ef7eb2e8f9f7 4 * Licensed under the Apache License, Version 2.0 (the "License");
<> 144:ef7eb2e8f9f7 5 * you may not use this file except in compliance with the License.
<> 144:ef7eb2e8f9f7 6 * You may obtain a copy of the License at
<> 144:ef7eb2e8f9f7 7 *
<> 144:ef7eb2e8f9f7 8 * http://www.apache.org/licenses/LICENSE-2.0
<> 144:ef7eb2e8f9f7 9 *
<> 144:ef7eb2e8f9f7 10 * Unless required by applicable law or agreed to in writing, software
<> 144:ef7eb2e8f9f7 11 * distributed under the License is distributed on an "AS IS" BASIS,
<> 144:ef7eb2e8f9f7 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
<> 144:ef7eb2e8f9f7 13 * See the License for the specific language governing permissions and
<> 144:ef7eb2e8f9f7 14 * limitations under the License.
<> 144:ef7eb2e8f9f7 15 */
<> 144:ef7eb2e8f9f7 16 #include <stddef.h>
<> 144:ef7eb2e8f9f7 17 #include "us_ticker_api.h"
<> 144:ef7eb2e8f9f7 18 #include "PeripheralNames.h"
<> 144:ef7eb2e8f9f7 19 #include "fsl_pit.h"
<> 144:ef7eb2e8f9f7 20 #include "fsl_lptmr.h"
<> 144:ef7eb2e8f9f7 21 #include "fsl_clock_config.h"
<> 144:ef7eb2e8f9f7 22
<> 144:ef7eb2e8f9f7 23 static int us_ticker_inited = 0;
<> 144:ef7eb2e8f9f7 24
<> 144:ef7eb2e8f9f7 25 void us_ticker_init(void) {
<> 144:ef7eb2e8f9f7 26 if (us_ticker_inited) {
<> 144:ef7eb2e8f9f7 27 return;
<> 144:ef7eb2e8f9f7 28 }
<> 144:ef7eb2e8f9f7 29 us_ticker_inited = 1;
<> 144:ef7eb2e8f9f7 30
<> 144:ef7eb2e8f9f7 31 // Need to initialize the clocks here as ticker init gets called before mbed_sdk_init
<> 144:ef7eb2e8f9f7 32 if (SystemCoreClock == DEFAULT_SYSTEM_CLOCK)
<> 144:ef7eb2e8f9f7 33 BOARD_BootClockRUN();
<> 144:ef7eb2e8f9f7 34
<> 144:ef7eb2e8f9f7 35 //Timer uses PIT
<> 144:ef7eb2e8f9f7 36 //Common for ticker/timer
<> 144:ef7eb2e8f9f7 37 uint32_t busClock;
<> 144:ef7eb2e8f9f7 38
<> 144:ef7eb2e8f9f7 39 // Structure to initialize PIT
<> 144:ef7eb2e8f9f7 40 pit_config_t pitConfig;
<> 144:ef7eb2e8f9f7 41
<> 144:ef7eb2e8f9f7 42 PIT_GetDefaultConfig(&pitConfig);
<> 144:ef7eb2e8f9f7 43 PIT_Init(PIT, &pitConfig);
<> 144:ef7eb2e8f9f7 44
<> 144:ef7eb2e8f9f7 45 busClock = CLOCK_GetFreq(kCLOCK_BusClk);
<> 144:ef7eb2e8f9f7 46
<> 144:ef7eb2e8f9f7 47 PIT_SetTimerPeriod(PIT, kPIT_Chnl_0, busClock / 1000000 - 1);
<> 144:ef7eb2e8f9f7 48 PIT_SetTimerPeriod(PIT, kPIT_Chnl_1, 0xFFFFFFFF);
<> 144:ef7eb2e8f9f7 49 PIT_SetTimerChainMode(PIT, kPIT_Chnl_1, true);
<> 144:ef7eb2e8f9f7 50 PIT_StartTimer(PIT, kPIT_Chnl_0);
<> 144:ef7eb2e8f9f7 51 PIT_StartTimer(PIT, kPIT_Chnl_1);
<> 144:ef7eb2e8f9f7 52
<> 144:ef7eb2e8f9f7 53 //Ticker uses LPTMR
<> 144:ef7eb2e8f9f7 54 lptmr_config_t lptmrConfig;
<> 144:ef7eb2e8f9f7 55 LPTMR_GetDefaultConfig(&lptmrConfig);
<> 144:ef7eb2e8f9f7 56 lptmrConfig.prescalerClockSource = kLPTMR_PrescalerClock_0;
<> 144:ef7eb2e8f9f7 57 LPTMR_Init(LPTMR0, &lptmrConfig);
<> 144:ef7eb2e8f9f7 58
<> 144:ef7eb2e8f9f7 59 busClock = CLOCK_GetFreq(kCLOCK_McgInternalRefClk);
<> 144:ef7eb2e8f9f7 60 LPTMR_SetTimerPeriod(LPTMR0, busClock / 1000000 - 1);
<> 144:ef7eb2e8f9f7 61 /* Set interrupt handler */
<> 144:ef7eb2e8f9f7 62 NVIC_SetVector(LPTMR0_IRQn, (uint32_t)us_ticker_irq_handler);
<> 144:ef7eb2e8f9f7 63 NVIC_EnableIRQ(LPTMR0_IRQn);
<> 144:ef7eb2e8f9f7 64 }
<> 144:ef7eb2e8f9f7 65
<> 144:ef7eb2e8f9f7 66
<> 144:ef7eb2e8f9f7 67 uint32_t us_ticker_read() {
<> 144:ef7eb2e8f9f7 68 if (!us_ticker_inited) {
<> 144:ef7eb2e8f9f7 69 us_ticker_init();
<> 144:ef7eb2e8f9f7 70 }
<> 144:ef7eb2e8f9f7 71
<> 144:ef7eb2e8f9f7 72 return ~(PIT_GetCurrentTimerCount(PIT, kPIT_Chnl_1));
<> 144:ef7eb2e8f9f7 73 }
<> 144:ef7eb2e8f9f7 74
<> 144:ef7eb2e8f9f7 75 void us_ticker_disable_interrupt(void) {
<> 144:ef7eb2e8f9f7 76 LPTMR_DisableInterrupts(LPTMR0, kLPTMR_TimerInterruptEnable);
<> 144:ef7eb2e8f9f7 77 }
<> 144:ef7eb2e8f9f7 78
<> 144:ef7eb2e8f9f7 79 void us_ticker_clear_interrupt(void) {
<> 144:ef7eb2e8f9f7 80 LPTMR_ClearStatusFlags(LPTMR0, kLPTMR_TimerCompareFlag);
<> 144:ef7eb2e8f9f7 81 }
<> 144:ef7eb2e8f9f7 82
<> 144:ef7eb2e8f9f7 83 void us_ticker_set_interrupt(timestamp_t timestamp) {
<> 144:ef7eb2e8f9f7 84 int delta = (int)(timestamp - us_ticker_read());
<> 144:ef7eb2e8f9f7 85 if (delta <= 0) {
<> 144:ef7eb2e8f9f7 86 // This event was in the past.
<> 144:ef7eb2e8f9f7 87 // Set the interrupt as pending, but don't process it here.
<> 144:ef7eb2e8f9f7 88 // This prevents a recurive loop under heavy load
<> 144:ef7eb2e8f9f7 89 // which can lead to a stack overflow.
<> 144:ef7eb2e8f9f7 90 NVIC_SetPendingIRQ(LPTMR0_IRQn);
<> 144:ef7eb2e8f9f7 91 return;
<> 144:ef7eb2e8f9f7 92 }
<> 144:ef7eb2e8f9f7 93
<> 144:ef7eb2e8f9f7 94 LPTMR_StopTimer(LPTMR0);
<> 144:ef7eb2e8f9f7 95 LPTMR_SetTimerPeriod(LPTMR0, (uint32_t)delta);
<> 144:ef7eb2e8f9f7 96 LPTMR_EnableInterrupts(LPTMR0, kLPTMR_TimerInterruptEnable);
<> 144:ef7eb2e8f9f7 97 LPTMR_StartTimer(LPTMR0);
<> 144:ef7eb2e8f9f7 98 }