Diff: targets/hal/TARGET_Freescale/TARGET_KSDK2_MCUS/TARGET_KL27Z/us_ticker.c

Revision:

121:7f86b4238bec

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/hal/TARGET_Freescale/TARGET_KSDK2_MCUS/TARGET_KL27Z/us_ticker.c	Tue May 03 00:15:16 2016 +0100
@@ -0,0 +1,98 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2013 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.
+ */
+#include <stddef.h>
+#include "us_ticker_api.h"
+#include "PeripheralNames.h"
+#include "fsl_pit.h"
+#include "fsl_lptmr.h"
+#include "fsl_clock_config.h"
+
+static int us_ticker_inited = 0;
+
+void us_ticker_init(void) {
+    if (us_ticker_inited) {
+        return;
+    }
+    us_ticker_inited = 1;
+
+    // Need to initialize the clocks here as ticker init gets called before mbed_sdk_init
+    if (SystemCoreClock == DEFAULT_SYSTEM_CLOCK)
+        BOARD_BootClockRUN();
+
+    //Timer uses PIT
+    //Common for ticker/timer
+    uint32_t busClock;
+
+    // Structure to initialize PIT
+    pit_config_t pitConfig;
+
+    PIT_GetDefaultConfig(&pitConfig);
+    PIT_Init(PIT, &pitConfig);
+
+    busClock = CLOCK_GetFreq(kCLOCK_BusClk);
+
+    PIT_SetTimerPeriod(PIT, kPIT_Chnl_0, busClock / 1000000 - 1);
+    PIT_SetTimerPeriod(PIT, kPIT_Chnl_1, 0xFFFFFFFF);
+    PIT_SetTimerChainMode(PIT, kPIT_Chnl_1, true);
+    PIT_StartTimer(PIT, kPIT_Chnl_0);
+    PIT_StartTimer(PIT, kPIT_Chnl_1);
+
+    //Ticker uses LPTMR
+    lptmr_config_t lptmrConfig;
+    LPTMR_GetDefaultConfig(&lptmrConfig);
+    lptmrConfig.prescalerClockSource = kLPTMR_PrescalerClock_0;
+    LPTMR_Init(LPTMR0, &lptmrConfig);
+
+    busClock = CLOCK_GetFreq(kCLOCK_McgInternalRefClk);
+    LPTMR_SetTimerPeriod(LPTMR0, busClock / 1000000 - 1);
+    /* Set interrupt handler */
+    NVIC_SetVector(LPTMR0_IRQn, (uint32_t)us_ticker_irq_handler);
+    NVIC_EnableIRQ(LPTMR0_IRQn);
+}
+
+
+uint32_t us_ticker_read() {
+    if (!us_ticker_inited) {
+        us_ticker_init();
+    }
+
+    return ~(PIT_GetCurrentTimerCount(PIT, kPIT_Chnl_1));
+}
+
+void us_ticker_disable_interrupt(void) {
+    LPTMR_DisableInterrupts(LPTMR0, kLPTMR_TimerInterruptEnable);
+}
+
+void us_ticker_clear_interrupt(void) {
+    LPTMR_ClearStatusFlags(LPTMR0, kLPTMR_TimerCompareFlag);
+}
+
+void us_ticker_set_interrupt(timestamp_t timestamp) {
+    int delta = (int)(timestamp - us_ticker_read());
+    if (delta <= 0) {
+        // This event was in the past.
+        // Set the interrupt as pending, but don't process it here.
+        // This prevents a recurive loop under heavy load
+        // which can lead to a stack overflow.
+        NVIC_SetPendingIRQ(LPTMR0_IRQn);
+        return;
+    }
+
+    LPTMR_StopTimer(LPTMR0);
+    LPTMR_SetTimerPeriod(LPTMR0, (uint32_t)delta);
+    LPTMR_EnableInterrupts(LPTMR0, kLPTMR_TimerInterruptEnable);
+    LPTMR_StartTimer(LPTMR0);
+}