Johannes Stratmann / mbed-dev

added prescaler for 16 bit pwm in LPC1347 target

Fork of mbed-dev by mbed official

targets/cmsis/TARGET_ARM_SSG/TARGET_BEETLE/systick_timer.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 /*
<> 144:ef7eb2e8f9f7 2 * PackageLicenseDeclared: Apache-2.0
<> 144:ef7eb2e8f9f7 3 * Copyright (c) 2015 ARM Limited
<> 144:ef7eb2e8f9f7 4 *
<> 144:ef7eb2e8f9f7 5 * Licensed under the Apache License, Version 2.0 (the "License");
<> 144:ef7eb2e8f9f7 6 * you may not use this file except in compliance with the License.
<> 144:ef7eb2e8f9f7 7 * You may obtain a copy of the License at
<> 144:ef7eb2e8f9f7 8 *
<> 144:ef7eb2e8f9f7 9 * http://www.apache.org/licenses/LICENSE-2.0
<> 144:ef7eb2e8f9f7 10 *
<> 144:ef7eb2e8f9f7 11 * Unless required by applicable law or agreed to in writing, software
<> 144:ef7eb2e8f9f7 12 * distributed under the License is distributed on an "AS IS" BASIS,
<> 144:ef7eb2e8f9f7 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
<> 144:ef7eb2e8f9f7 14 * See the License for the specific language governing permissions and
<> 144:ef7eb2e8f9f7 15 * limitations under the License.
<> 144:ef7eb2e8f9f7 16 */
<> 144:ef7eb2e8f9f7 17
<> 144:ef7eb2e8f9f7 18 #include "cmsis.h"
<> 144:ef7eb2e8f9f7 19 #include "systick_timer.h"
<> 144:ef7eb2e8f9f7 20
<> 144:ef7eb2e8f9f7 21 volatile uint32_t MyTicks;
<> 144:ef7eb2e8f9f7 22
<> 144:ef7eb2e8f9f7 23 /* Private Data SysTick */
<> 144:ef7eb2e8f9f7 24 static uint32_t clock;
<> 144:ef7eb2e8f9f7 25
<> 144:ef7eb2e8f9f7 26 /*
<> 144:ef7eb2e8f9f7 27 * This Timer is written for MBED OS so the interrupt
<> 144:ef7eb2e8f9f7 28 * is used to keep track of the overflow.
<> 144:ef7eb2e8f9f7 29 */
<> 144:ef7eb2e8f9f7 30 #define SYSTICK_MAX_RELOAD 0xFFFFFFFF
<> 144:ef7eb2e8f9f7 31 #define SYSTICK_DIVIDER_US (SystemCoreClock/1000000)
<> 144:ef7eb2e8f9f7 32
<> 144:ef7eb2e8f9f7 33 void SysTick_IRQ_Handler(void)
<> 144:ef7eb2e8f9f7 34 {
<> 144:ef7eb2e8f9f7 35 MyTicks++;
<> 144:ef7eb2e8f9f7 36 #if 0
<> 144:ef7eb2e8f9f7 37 printf("System Tick Interrupt: %u\n\r", MyTicks);
<> 144:ef7eb2e8f9f7 38 #endif
<> 144:ef7eb2e8f9f7 39 }
<> 144:ef7eb2e8f9f7 40
<> 144:ef7eb2e8f9f7 41 /*
<> 144:ef7eb2e8f9f7 42 * SysTick_Initialize(): Initializes the SysTick timer
<> 144:ef7eb2e8f9f7 43 */
<> 144:ef7eb2e8f9f7 44 void SysTick_Initialize(void)
<> 144:ef7eb2e8f9f7 45 {
<> 144:ef7eb2e8f9f7 46 clock = SYSTICK_MAX_RELOAD;
<> 144:ef7eb2e8f9f7 47 #if 0
<> 144:ef7eb2e8f9f7 48 printf("\n\rEnable System Tick Interrupt...\n\r");
<> 144:ef7eb2e8f9f7 49 #endif
<> 144:ef7eb2e8f9f7 50 MyTicks=0;
<> 144:ef7eb2e8f9f7 51
<> 144:ef7eb2e8f9f7 52 /* SysTick Reload Value Register */
<> 144:ef7eb2e8f9f7 53 SysTick->LOAD = clock;
<> 144:ef7eb2e8f9f7 54
<> 144:ef7eb2e8f9f7 55 /*
<> 144:ef7eb2e8f9f7 56 * SysTick_CTRL_CLKSOURCE_Msk : Use core's clock
<> 144:ef7eb2e8f9f7 57 * SysTick_CTRL_ENABLE_Msk : Enable SysTick
<> 144:ef7eb2e8f9f7 58 * SysTick_CTRL_TICKINT_Msk : Active the SysTick interrupt on the NVIC
<> 144:ef7eb2e8f9f7 59 */
<> 144:ef7eb2e8f9f7 60 SysTick->CTRL = SysTick_CTRL_CLKSOURCE_Msk
<> 144:ef7eb2e8f9f7 61 | SysTick_CTRL_ENABLE_Msk
<> 144:ef7eb2e8f9f7 62 | SysTick_CTRL_TICKINT_Msk;
<> 144:ef7eb2e8f9f7 63
<> 144:ef7eb2e8f9f7 64 /* Register the Interrupt */
<> 144:ef7eb2e8f9f7 65 NVIC_SetVector(SysTick_IRQn, (uint32_t)SysTick_IRQ_Handler);
<> 144:ef7eb2e8f9f7 66 NVIC_EnableIRQ(SysTick_IRQn);
<> 144:ef7eb2e8f9f7 67 }
<> 144:ef7eb2e8f9f7 68
<> 144:ef7eb2e8f9f7 69 /*
<> 144:ef7eb2e8f9f7 70 * SysTick_Disable(): Disables the SysTick timer
<> 144:ef7eb2e8f9f7 71 */
<> 144:ef7eb2e8f9f7 72 void SysTick_Disable(void)
<> 144:ef7eb2e8f9f7 73 {
<> 144:ef7eb2e8f9f7 74 /* Disable SysTick */
<> 144:ef7eb2e8f9f7 75 SysTick->CTRL = 0;
<> 144:ef7eb2e8f9f7 76 }
<> 144:ef7eb2e8f9f7 77
<> 144:ef7eb2e8f9f7 78 /*
<> 144:ef7eb2e8f9f7 79 * SysTick_Read(): Read SysTick Value
<> 144:ef7eb2e8f9f7 80 * @return: the SysTick VALUE
<> 144:ef7eb2e8f9f7 81 */
<> 144:ef7eb2e8f9f7 82 uint32_t SysTick_Read(void)
<> 144:ef7eb2e8f9f7 83 {
<> 144:ef7eb2e8f9f7 84 return ((clock - (SysTick->VAL)) / SYSTICK_DIVIDER_US);
<> 144:ef7eb2e8f9f7 85 }
<> 144:ef7eb2e8f9f7 86
<> 144:ef7eb2e8f9f7 87 /*
<> 144:ef7eb2e8f9f7 88 * SysTick_Overflow(): Read SysTick Overflow Value
<> 144:ef7eb2e8f9f7 89 * @return: the SysTick Overflow VALUE
<> 144:ef7eb2e8f9f7 90 */
<> 144:ef7eb2e8f9f7 91 uint32_t SysTick_Overflow(void)
<> 144:ef7eb2e8f9f7 92 {
<> 144:ef7eb2e8f9f7 93 return MyTicks;
<> 144:ef7eb2e8f9f7 94 }