Diff: mbed-dev/targets/TARGET_Freescale/TARGET_K20XX/TARGET_TEENSY3_1/us_ticker.c

Revision:

18:6a4db94011d3

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed-dev/targets/TARGET_Freescale/TARGET_K20XX/TARGET_TEENSY3_1/us_ticker.c	Sun May 14 23:18:57 2017 +0000
@@ -0,0 +1,84 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2015 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 "clk_freqs.h"
+
+static int us_ticker_inited = 0;
+
+void us_ticker_init(void) {
+    if (us_ticker_inited)
+        return;
+    us_ticker_inited = 1;
+    
+    SIM->SCGC6 |= SIM_SCGC6_PIT_MASK;   // Clock PIT
+    PIT->MCR = 0;                       // Enable PIT
+    
+    //Timer on PIT0+1, ticker on PIT 2+3
+    //Init timer
+    PIT->CHANNEL[1].LDVAL = 0xFFFFFFFF;
+    PIT->CHANNEL[1].TCTRL = PIT_TCTRL_CHN_MASK | PIT_TCTRL_TEN_MASK;   // Start timer 1, chained to timer 0
+    
+    // Use channel 0 as a prescaler for channel 1
+    uint32_t ldval = (bus_frequency() + 500000) / 1000000 - 1;
+    PIT->CHANNEL[0].LDVAL = ldval;
+    PIT->CHANNEL[0].TCTRL = PIT_TCTRL_TEN_MASK;    // Start timer
+    
+    //Init ticker
+    PIT->CHANNEL[2].LDVAL = ldval;
+    PIT->CHANNEL[2].TCTRL = PIT_TCTRL_TEN_MASK;    // Start timer 2 as prescaler
+    
+    NVIC_SetVector(PIT3_IRQn, (uint32_t)us_ticker_irq_handler);
+    NVIC_EnableIRQ(PIT3_IRQn);
+}
+
+/******************************************************************************
+ * Timer for us timing.
+ ******************************************************************************/
+
+uint32_t us_ticker_read() {
+    if (!us_ticker_inited)
+        us_ticker_init();
+   
+   return ~(PIT->CHANNEL[1].CVAL);
+}
+
+/******************************************************************************
+ * Ticker Event
+ ******************************************************************************/
+
+void us_ticker_disable_interrupt(void) {
+    PIT->CHANNEL[3].TCTRL &= ~PIT_TCTRL_TIE_MASK;
+}
+
+void us_ticker_clear_interrupt(void) {
+    PIT->CHANNEL[3].TFLG = 1;
+}
+
+void us_ticker_set_interrupt(timestamp_t timestamp) {
+    int delta = (int)((uint32_t)timestamp - us_ticker_read());
+    if (delta <= 0) {
+        // This event was in the past:
+        us_ticker_irq_handler();
+        return;
+    }
+    
+    PIT->CHANNEL[3].TCTRL = 0;
+    PIT->CHANNEL[3].LDVAL = delta;
+    PIT->CHANNEL[3].TCTRL = PIT_TCTRL_TIE_MASK | PIT_TCTRL_TEN_MASK | PIT_TCTRL_CHN_MASK;
+    
+}