Diff: mbed-dev/targets/TARGET_ARM_SSG/TARGET_BEETLE/us_ticker.c

Revision:

18:6a4db94011d3

diff -r f713758f6238 -r 6a4db94011d3 mbed-dev/targets/TARGET_ARM_SSG/TARGET_BEETLE/us_ticker.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed-dev/targets/TARGET_ARM_SSG/TARGET_BEETLE/us_ticker.c	Sun May 14 23:18:57 2017 +0000
@@ -0,0 +1,116 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 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 "cmsis.h"
+#include "us_ticker_api.h"
+#include "PeripheralNames.h"
+/* Private data */
+/* us_ticker reload value */
+static uint32_t us_ticker_reload = 0x0; /* Max Value */
+/* us ticker initialized */
+static uint32_t us_ticker_inited = 0;
+/* us ticker overflow */
+static uint32_t us_ticker_overflow_delta = 0;
+/* us ticker overflow limit */
+static uint32_t us_ticker_overflow_limit = 0;
+
+void __us_ticker_irq_handler(void) {
+    Timer_ClearInterrupt(TIMER1);
+    /*
+     * For each overflow event adds the timer max represented value to
+     * the delta. This allows the us_ticker to keep track of the elapsed
+     * time:
+     * elapsed_time = (num_overflow * overflow_limit) + current_time
+     */
+    us_ticker_overflow_delta += us_ticker_overflow_limit;
+}
+
+void us_ticker_init(void) {
+    uint32_t us_ticker_irqn0 = 0;
+    uint32_t us_ticker_irqn1 = 0;
+
+    if (us_ticker_inited)
+        return;
+    us_ticker_inited = 1;
+
+    /* Initialize Timer 0 */
+    Timer_Initialize(TIMER0, us_ticker_reload);
+    /* Enable Timer 0 */
+    Timer_Enable(TIMER0);
+
+    /* Initialize Timer 1 */
+    Timer_Initialize(TIMER1, us_ticker_reload);
+    /* Enable Timer 1 */
+    Timer_Enable(TIMER1);
+
+    /* Timer 0 get IRQn */
+    us_ticker_irqn0 = Timer_GetIRQn(TIMER0);
+    NVIC_SetVector((IRQn_Type)us_ticker_irqn0, (uint32_t)us_ticker_irq_handler);
+    NVIC_EnableIRQ((IRQn_Type)us_ticker_irqn0);
+
+    /* Timer 1 get IRQn */
+    us_ticker_irqn1 = Timer_GetIRQn(TIMER1);
+    NVIC_SetVector((IRQn_Type)us_ticker_irqn1, (uint32_t)__us_ticker_irq_handler);
+    NVIC_EnableIRQ((IRQn_Type)us_ticker_irqn1);
+
+    /* Timer set interrupt on TIMER1 */
+    Timer_SetInterrupt(TIMER1, TIMER_DEFAULT_RELOAD);
+
+    /*
+     * Set us_ticker Overflow limit. The us_ticker overflow limit is required
+     * to calculated the return value of the us_ticker read function in us
+     * on 32bit.
+     * A 32bit us value cannot be represented directly in the Timer Load
+     * register if it is greater than (0xFFFFFFFF ticks)/TIMER_DIVIDER_US.
+     */
+    us_ticker_overflow_limit = Timer_GetReloadValue(TIMER1);
+}
+
+uint32_t us_ticker_read() {
+    uint32_t return_value = 0;
+
+    if (!us_ticker_inited)
+        us_ticker_init();
+
+    return_value = us_ticker_overflow_delta + Timer_Read(TIMER1);
+
+    return return_value;
+}
+
+void us_ticker_set_interrupt(timestamp_t timestamp) {
+    int32_t delta = 0;
+
+    if (!us_ticker_inited)
+        us_ticker_init();
+    delta = (int32_t)(timestamp - us_ticker_read());
+    /* Check if the event was in the past */
+    if (delta <= 0) {
+        /* This event was in the past */
+        Timer_SetInterrupt(TIMER0, 0);
+        return;
+    }
+
+    /* If the event was not in the past enable interrupt */
+    Timer_SetInterrupt(TIMER0, delta);
+}
+
+void us_ticker_disable_interrupt(void) {
+    Timer_DisableInterrupt(TIMER0);
+}
+
+void us_ticker_clear_interrupt(void) {
+    Timer_ClearInterrupt(TIMER0);
+}