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_K66F/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_clock_config.h"
<> 144:ef7eb2e8f9f7 21
<> 144:ef7eb2e8f9f7 22 static int us_ticker_inited = 0;
<> 144:ef7eb2e8f9f7 23
<> 144:ef7eb2e8f9f7 24 void us_ticker_init(void) {
<> 144:ef7eb2e8f9f7 25 if (us_ticker_inited) {
<> 144:ef7eb2e8f9f7 26 return;
<> 144:ef7eb2e8f9f7 27 }
<> 144:ef7eb2e8f9f7 28 us_ticker_inited = 1;
<> 144:ef7eb2e8f9f7 29 // Need to initialize the clocks here as ticker init gets called before mbed_sdk_init
<> 144:ef7eb2e8f9f7 30 if (SystemCoreClock == DEFAULT_SYSTEM_CLOCK)
<> 144:ef7eb2e8f9f7 31 BOARD_BootClockRUN();
<> 144:ef7eb2e8f9f7 32 //Common for ticker/timer
<> 144:ef7eb2e8f9f7 33 uint32_t busClock;
<> 144:ef7eb2e8f9f7 34 // Structure to initialize PIT
<> 144:ef7eb2e8f9f7 35 pit_config_t pitConfig;
<> 144:ef7eb2e8f9f7 36
<> 144:ef7eb2e8f9f7 37 PIT_GetDefaultConfig(&pitConfig);
<> 144:ef7eb2e8f9f7 38 PIT_Init(PIT, &pitConfig);
<> 144:ef7eb2e8f9f7 39
<> 144:ef7eb2e8f9f7 40 busClock = CLOCK_GetFreq(kCLOCK_BusClk);
<> 144:ef7eb2e8f9f7 41
<> 144:ef7eb2e8f9f7 42 //Timer
<> 144:ef7eb2e8f9f7 43 PIT_SetTimerPeriod(PIT, kPIT_Chnl_0, busClock / 1000000 - 1);
<> 144:ef7eb2e8f9f7 44 PIT_SetTimerPeriod(PIT, kPIT_Chnl_1, 0xFFFFFFFF);
<> 144:ef7eb2e8f9f7 45 PIT_SetTimerChainMode(PIT, kPIT_Chnl_1, true);
<> 144:ef7eb2e8f9f7 46 PIT_StartTimer(PIT, kPIT_Chnl_0);
<> 144:ef7eb2e8f9f7 47 PIT_StartTimer(PIT, kPIT_Chnl_1);
<> 144:ef7eb2e8f9f7 48
<> 144:ef7eb2e8f9f7 49 //Ticker
<> 144:ef7eb2e8f9f7 50 PIT_SetTimerPeriod(PIT, kPIT_Chnl_2, busClock / 1000000 - 1);
<> 144:ef7eb2e8f9f7 51 PIT_SetTimerChainMode(PIT, kPIT_Chnl_3, true);
<> 144:ef7eb2e8f9f7 52 NVIC_SetVector(PIT3_IRQn, (uint32_t)us_ticker_irq_handler);
<> 144:ef7eb2e8f9f7 53 NVIC_EnableIRQ(PIT3_IRQn);
<> 144:ef7eb2e8f9f7 54 }
<> 144:ef7eb2e8f9f7 55
<> 144:ef7eb2e8f9f7 56
<> 144:ef7eb2e8f9f7 57 uint32_t us_ticker_read() {
<> 144:ef7eb2e8f9f7 58 if (!us_ticker_inited) {
<> 144:ef7eb2e8f9f7 59 us_ticker_init();
<> 144:ef7eb2e8f9f7 60 }
<> 144:ef7eb2e8f9f7 61
<> 144:ef7eb2e8f9f7 62 return ~(PIT_GetCurrentTimerCount(PIT, kPIT_Chnl_1));
<> 144:ef7eb2e8f9f7 63 }
<> 144:ef7eb2e8f9f7 64
<> 144:ef7eb2e8f9f7 65 void us_ticker_disable_interrupt(void) {
<> 144:ef7eb2e8f9f7 66 PIT_DisableInterrupts(PIT, kPIT_Chnl_3, kPIT_TimerInterruptEnable);
<> 144:ef7eb2e8f9f7 67 }
<> 144:ef7eb2e8f9f7 68
<> 144:ef7eb2e8f9f7 69 void us_ticker_clear_interrupt(void) {
<> 144:ef7eb2e8f9f7 70 PIT_ClearStatusFlags(PIT, kPIT_Chnl_3, PIT_TFLG_TIF_MASK);
<> 144:ef7eb2e8f9f7 71 }
<> 144:ef7eb2e8f9f7 72
<> 144:ef7eb2e8f9f7 73 void us_ticker_set_interrupt(timestamp_t timestamp) {
<> 144:ef7eb2e8f9f7 74 int delta = (int)(timestamp - us_ticker_read());
<> 144:ef7eb2e8f9f7 75 if (delta <= 0) {
<> 144:ef7eb2e8f9f7 76 // This event was in the past.
<> 144:ef7eb2e8f9f7 77 // Set the interrupt as pending, but don't process it here.
<> 144:ef7eb2e8f9f7 78 // This prevents a recurive loop under heavy load
<> 144:ef7eb2e8f9f7 79 // which can lead to a stack overflow.
<> 144:ef7eb2e8f9f7 80 NVIC_SetPendingIRQ(PIT3_IRQn);
<> 144:ef7eb2e8f9f7 81 return;
<> 144:ef7eb2e8f9f7 82 }
<> 144:ef7eb2e8f9f7 83
<> 144:ef7eb2e8f9f7 84 PIT_StopTimer(PIT, kPIT_Chnl_3);
<> 144:ef7eb2e8f9f7 85 PIT_StopTimer(PIT, kPIT_Chnl_2);
<> 144:ef7eb2e8f9f7 86 PIT_SetTimerPeriod(PIT, kPIT_Chnl_3, (uint32_t)delta);
<> 144:ef7eb2e8f9f7 87 PIT_EnableInterrupts(PIT, kPIT_Chnl_3, kPIT_TimerInterruptEnable);
<> 144:ef7eb2e8f9f7 88 PIT_StartTimer(PIT, kPIT_Chnl_3);
<> 144:ef7eb2e8f9f7 89 PIT_StartTimer(PIT, kPIT_Chnl_2);
<> 144:ef7eb2e8f9f7 90 }