Diff: targets/hal/TARGET_STM/TARGET_STM32L0/us_ticker.c

Revision:

0:9b334a45a8ff

Child:

136:5728e9819171

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/hal/TARGET_STM/TARGET_STM32L0/us_ticker.c	Thu Oct 01 15:25:22 2015 +0300
@@ -0,0 +1,113 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2015, STMicroelectronics
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ * 3. Neither the name of STMicroelectronics nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#include <stddef.h>
+#include "us_ticker_api.h"
+#include "PeripheralNames.h"
+
+// Timer selection
+#define TIM_MST TIM21
+
+static TIM_HandleTypeDef TimMasterHandle;
+static int us_ticker_inited = 0;
+
+volatile uint32_t SlaveCounter = 0;
+volatile uint32_t oc_int_part = 0;
+volatile uint16_t oc_rem_part = 0;
+
+void set_compare(uint16_t count)
+{
+    TimMasterHandle.Instance = TIM_MST;
+    // Set new output compare value
+    __HAL_TIM_SetCompare(&TimMasterHandle, TIM_CHANNEL_1, count);
+    // Enable IT
+    __HAL_TIM_ENABLE_IT(&TimMasterHandle, TIM_IT_CC1);
+}
+
+void us_ticker_init(void)
+{
+    if (us_ticker_inited) return;
+    us_ticker_inited = 1;
+
+    HAL_InitTick(0); // The passed value is not used
+}
+
+uint32_t us_ticker_read()
+{
+    uint32_t counter, counter2;
+    if (!us_ticker_inited) us_ticker_init();
+    // A situation might appear when Master overflows right after Slave is read and before the
+    // new (overflowed) value of Master is read. Which would make the code below consider the
+    // previous (incorrect) value of Slave and the new value of Master, which would return a
+    // value in the past. Avoid this by computing consecutive values of the timer until they
+    // are properly ordered.
+    counter = (uint32_t)(SlaveCounter << 16);
+    counter += TIM_MST->CNT;
+    while (1) {
+        counter2 = (uint32_t)(SlaveCounter << 16);
+        counter2 += TIM_MST->CNT;
+        if (counter2 > counter) {
+            break;
+        }
+        counter = counter2;
+    }
+    return counter2;
+}
+
+void us_ticker_set_interrupt(timestamp_t timestamp)
+{
+    int delta = (int)((uint32_t)timestamp - us_ticker_read());
+    uint16_t cval = TIM_MST->CNT;
+
+    if (delta <= 0) { // This event was in the past
+        us_ticker_irq_handler();
+    } else {
+        oc_int_part = (uint32_t)(delta >> 16);
+        oc_rem_part = (uint16_t)(delta & 0xFFFF);
+        if (oc_rem_part <= (0xFFFF - cval)) {
+            set_compare(cval + oc_rem_part);
+            oc_rem_part = 0;
+        } else {
+            set_compare(0xFFFF);
+            oc_rem_part = oc_rem_part - (0xFFFF - cval);
+        }
+    }
+}
+
+void us_ticker_disable_interrupt(void)
+{
+    TimMasterHandle.Instance = TIM_MST;
+    __HAL_TIM_DISABLE_IT(&TimMasterHandle, TIM_IT_CC1);
+}
+
+void us_ticker_clear_interrupt(void)
+{
+    TimMasterHandle.Instance = TIM_MST;
+    if (__HAL_TIM_GET_FLAG(&TimMasterHandle, TIM_FLAG_CC1) == SET) {
+        __HAL_TIM_CLEAR_FLAG(&TimMasterHandle, TIM_FLAG_CC1);
+    }
+}