Diff: targets/hal/TARGET_NXP/TARGET_LPC82X/us_ticker.c

Revision:

337:6ed01c00b962

Child:

509:53fc1beb5664

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/hal/TARGET_NXP/TARGET_LPC82X/us_ticker.c	Mon Oct 06 10:00:08 2014 +0100
@@ -0,0 +1,89 @@
+/* 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"
+
+static int us_ticker_inited = 0;
+static int ticker_expired = 0;
+
+#define US_TICKER_TIMER_IRQn     MRT_IRQn
+#define MRT_CLOCK_MHZ            30
+
+void us_ticker_init(void)
+{
+    if (us_ticker_inited)
+        return;
+
+    us_ticker_inited = 1;
+
+    // Enable the MRT clock
+    LPC_SYSCON->SYSAHBCLKCTRL |= (1 << 10);
+
+    // Clear peripheral reset the MRT
+    LPC_SYSCON->PRESETCTRL |= (1 << 7);
+
+    // Force load interval value
+    LPC_MRT->INTVAL0 = 0xFFFFFFFFUL;
+    // Enable ch0 interrupt
+    LPC_MRT->CTRL0 = 1;
+
+    // Force load interval value
+    LPC_MRT->INTVAL1 = 0x80000000UL;
+    // Disable ch1 interrupt
+    LPC_MRT->CTRL1 = 0;
+
+    // Set MRT interrupt vector
+    NVIC_SetVector(US_TICKER_TIMER_IRQn, (uint32_t)us_ticker_irq_handler);
+    NVIC_EnableIRQ(US_TICKER_TIMER_IRQn);
+}
+
+uint32_t us_ticker_read()
+{
+    if (!us_ticker_inited)
+        us_ticker_init();
+
+    // Generate ticker value
+    // MRT source clock is SystemCoreClock (30MHz) and 31-bit down count timer
+    // Calculate expected value using number of expired times
+    return (0x7FFFFFFFUL - LPC_MRT->TIMER0)/MRT_CLOCK_MHZ + (ticker_expired * (0x80000000UL/MRT_CLOCK_MHZ));
+}
+
+
+void us_ticker_set_interrupt(timestamp_t timestamp)
+{
+    // Force load interval value
+    LPC_MRT->INTVAL1 = (((timestamp - us_ticker_read()) * MRT_CLOCK_MHZ) | 0x80000000UL);
+
+    // Enable interrupt 
+    LPC_MRT->CTRL1 |= 1;
+}
+
+void us_ticker_disable_interrupt()
+{
+    LPC_MRT->CTRL1 &= ~1;
+}
+
+void us_ticker_clear_interrupt()
+{
+    if (LPC_MRT->STAT1 & 1)
+        LPC_MRT->STAT1 = 1;
+    
+    if (LPC_MRT->STAT0 & 1) {
+        LPC_MRT->STAT0 = 1;
+        ticker_expired++;
+    }
+}