Diff: mbed-dev/targets/TARGET_ONSEMI/TARGET_NCS36510/ncs36510_us_ticker_api.c

Revision:

18:6a4db94011d3

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed-dev/targets/TARGET_ONSEMI/TARGET_NCS36510/ncs36510_us_ticker_api.c	Sun May 14 23:18:57 2017 +0000
@@ -0,0 +1,209 @@
+/**
+ ******************************************************************************
+ * @file us_ticker_api.h
+ * @brief Implementation of a Timer driver
+ * @internal
+ * @author ON Semiconductor
+ * $Rev:  $
+ * $Date: 2015-11-15 $
+ ******************************************************************************
+ * Copyright 2016 Semiconductor Components Industries LLC (d/b/a “ON Semiconductor”).
+ * All rights reserved.  This software and/or documentation is licensed by ON Semiconductor
+ * under limited terms and conditions.  The terms and conditions pertaining to the software
+ * and/or documentation are available at http://www.onsemi.com/site/pdf/ONSEMI_T&C.pdf
+ * (“ON Semiconductor Standard Terms and Conditions of Sale, Section 8 Software”) and
+ * if applicable the software license agreement.  Do not use this software and/or
+ * documentation unless you have carefully read and you agree to the limited terms and
+ * conditions.  By using this software and/or documentation, you agree to the limited
+ * terms and conditions.
+ *
+ * THIS SOFTWARE IS PROVIDED "AS IS".  NO WARRANTIES, WHETHER EXPRESS, IMPLIED
+ * OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE.
+ * ON SEMICONDUCTOR SHALL NOT, IN ANY CIRCUMSTANCES, BE LIABLE FOR SPECIAL,
+ * INCIDENTAL, OR CONSEQUENTIAL DAMAGES, FOR ANY REASON WHATSOEVER.
+ * @endinternal
+ *
+ * @ingroup timer
+*/
+
+#include <stddef.h>
+#include "timer.h"
+
+#define US_TIMER  TIMER0
+#define US_TICKER TIMER1
+
+static int us_ticker_inited = 0;
+
+static void us_timer_init(void);
+
+static uint32_t us_ticker_target = 0;
+static volatile uint32_t msb_counter = 0;
+
+void us_ticker_init(void)
+{
+    if (!us_ticker_inited) {
+        us_timer_init();
+    }
+}
+
+/*******************************************************************************
+ * Timer for us timing reference
+ *
+ * Uptime counter for scheduling reference.  It uses TIMER0.
+ * The NCS36510 does not have a 32 bit timer nor the option to chain timers,
+ * which is why a software timer is required to get 32-bit word length.
+ ******************************************************************************/
+/* TODO - Need some sort of load value/prescale calculation for non-32MHz clock */
+/* TODO - Add msb_counter rollover protection at 16 bits count? */
+/* TODO - How is overflow handled? */
+
+/* Timer 0 for free running time */
+extern void us_timer_isr(void)
+{
+    TIM0REG->CLEAR = 0;
+    msb_counter++;
+}
+
+/* Initializing TIMER 0(TImer) and TIMER 1(Ticker) */
+static void us_timer_init(void)
+{
+    /* Enable the timer0 periphery clock */
+    CLOCK_ENABLE(CLOCK_TIMER0);
+    /* Enable the timer0 periphery clock */
+    CLOCK_ENABLE(CLOCK_TIMER1);
+
+    /* Timer init */
+    /* load timer value */
+    TIM0REG->LOAD = 0xFFFF;
+
+    /* set timer prescale 32 (1 us), mode & enable */
+    TIM0REG->CONTROL.WORD = ((CLK_DIVIDER_32        << TIMER_PRESCALE_BIT_POS) |
+                             (TIME_MODE_PERIODIC    << TIMER_MODE_BIT_POS) |
+                             (TIMER_ENABLE_BIT      << TIMER_ENABLE_BIT_POS));
+
+    /* Ticker init */
+    /* load timer value */
+    TIM1REG->LOAD = 0xFFFF;
+
+    /* set timer prescale 32 (1 us), mode & enable */
+    TIM1REG->CONTROL.WORD = ((CLK_DIVIDER_32        << TIMER_PRESCALE_BIT_POS) |
+                             (TIME_MODE_PERIODIC    << TIMER_MODE_BIT_POS));
+
+    /* Register & enable interrupt associated with the timer */
+    NVIC_SetVector(Tim0_IRQn,(uint32_t)us_timer_isr);
+    NVIC_SetVector(Tim1_IRQn,(uint32_t)us_ticker_isr);
+
+    /* Clear pending irqs */
+    NVIC_ClearPendingIRQ(Tim0_IRQn);
+    NVIC_ClearPendingIRQ(Tim1_IRQn);
+
+    /* Setup NVIC for timer */
+    NVIC_EnableIRQ(Tim0_IRQn);
+    NVIC_EnableIRQ(Tim1_IRQn);
+
+    us_ticker_inited = 1;
+}
+
+/* Reads 32 bit timer's current value (16 bit s/w timer | 16 bit h/w timer) */
+uint32_t us_ticker_read()
+{
+    uint32_t retval, tim0cval;
+
+    if (!us_ticker_inited) {
+        us_timer_init();
+    }
+
+    /* Get the current tick from the hw and sw timers */
+    tim0cval = TIM0REG->VALUE;         /* read current time */
+    retval = (0xFFFF - tim0cval);      /* subtract down count */
+
+    NVIC_DisableIRQ(Tim0_IRQn);
+    if (TIM0REG->CONTROL.BITS.INT) {
+        TIM0REG->CLEAR = 0;
+        msb_counter++;
+        tim0cval = TIM0REG->VALUE;    /* read current time again after interrupt */
+        retval = (0xFFFF - tim0cval);
+    }
+    retval |= msb_counter << 16;      /* add software bits */
+    NVIC_EnableIRQ(Tim0_IRQn);
+    return retval;
+}
+
+/*******************************************************************************
+ * Event Timer
+ *
+ * Schedules interrupts at given (32bit)us interval of time.  It uses TIMER1.
+ * The NCS36510 does not have a 32 bit timer nor the option to chain timers,
+ * which is why a software timer is required to get 32-bit word length.
+ *******************************************************************************/
+/* TODO - Need some sort of load value/prescale calculation for non-32MHz clock */
+
+/* TImer 1 disbale interrupt */
+void us_ticker_disable_interrupt(void)
+{
+    /* Disable the TIMER1 interrupt */
+    TIM1REG->CONTROL.BITS.ENABLE = 0x0;
+}
+
+/* TImer 1 clear interrupt */
+void us_ticker_clear_interrupt(void)
+{
+    /* Clear the Ticker (TIMER1) interrupt */
+    TIM1REG->CLEAR = 0;
+}
+
+/* Setting TImer 1 (ticker) */
+inline static void ticker_set(uint32_t count)
+{
+    /* Disable TIMER1, load the new value, and re-enable */
+    TIM1REG->CONTROL.BITS.ENABLE = 0;
+    TIM1REG->LOAD = count;
+    TIM1REG->CONTROL.BITS.ENABLE = 1;
+}
+
+/* TImer 1 - ticker ISR */
+extern void us_ticker_isr(void)
+{
+    /* Clear IRQ flag */
+    TIM1REG->CLEAR = 0;
+
+    int32_t delta = us_ticker_target - us_ticker_read();
+    if (delta <= 0) {
+        TIM1REG->CONTROL.BITS.ENABLE = False;
+        us_ticker_irq_handler();
+    } else {
+        // Clamp at max value of timer
+        if (delta > 0xFFFF) {
+            delta = 0xFFFF;
+        }
+
+        ticker_set(delta);
+    }
+}
+
+/* Set timer 1 ticker interrupt */
+void us_ticker_set_interrupt(timestamp_t timestamp)
+{
+    us_ticker_target = (uint32_t)timestamp;
+    int32_t delta = us_ticker_target - us_ticker_read();
+
+    if (delta <= 0) {
+        /* This event was in the past */
+        //us_ticker_irq_handler();
+        // 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(Tim1_IRQn);
+
+        return;
+    }
+
+    // Clamp at max value of timer
+    if (delta > 0xFFFF) {
+        delta = 0xFFFF;
+    }
+
+    ticker_set(delta);
+}