Lancaster University / mbed-src

Lancaster University's (short term!) clone of mbed-src for micro:bit. This is a copy of the github branch https://github.com/lancaster-university/mbed-classic

Fork of mbed-src by mbed official

common/us_ticker_api.c@641:be9b2017785a, 2016-07-13 (annotated)

Committer:
LancasterUniversity
Date:
Wed Jul 13 12:52:54 2016 +0100
Revision:
641:be9b2017785a
Parent:
525:c320967f86b9 
Synchronized with git rev 1fb8ab4c

Author: James Devine

mbed-classic: BUGFIX for timer when using wait_ms from interrupt context



Previously if a user used wait[_ms,_us] in interrupt context the device would

hang indefinitely. This was due to incrementing overflowCount from

interrupt context only.



This meant that if a user used wait[_ms,_us] in an ISR with

the same or greater interrupt priority, it would result in an infinite

loop as the overflowCount variable would never be incremented, and

wait[_ms,_us] would never return.



This patch simply applies a better solution for the race condition

mentioned in the previous commit. It instead disables the timer1

interrupt and increments the overflowCount variable, preventing

the race condition whilst supporting wait[_ms,_us] in interrupt

context.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
emilmont 4:c4bfb462ca53 1 /* mbed Microcontroller Library
mbed_official 525:c320967f86b9 2 * Copyright (c) 2015 ARM Limited
emilmont 4:c4bfb462ca53 3 *
emilmont 4:c4bfb462ca53 4 * Licensed under the Apache License, Version 2.0 (the "License");
emilmont 4:c4bfb462ca53 5 * you may not use this file except in compliance with the License.
emilmont 4:c4bfb462ca53 6 * You may obtain a copy of the License at
emilmont 4:c4bfb462ca53 7 *
emilmont 4:c4bfb462ca53 8 * http://www.apache.org/licenses/LICENSE-2.0
emilmont 4:c4bfb462ca53 9 *
emilmont 4:c4bfb462ca53 10 * Unless required by applicable law or agreed to in writing, software
emilmont 4:c4bfb462ca53 11 * distributed under the License is distributed on an "AS IS" BASIS,
emilmont 4:c4bfb462ca53 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
emilmont 4:c4bfb462ca53 13 * See the License for the specific language governing permissions and
emilmont 4:c4bfb462ca53 14 * limitations under the License.
emilmont 4:c4bfb462ca53 15 */
emilmont 4:c4bfb462ca53 16 #include "us_ticker_api.h"
emilmont 4:c4bfb462ca53 17
mbed_official 525:c320967f86b9 18 static ticker_event_queue_t events;
mbed_official 221:8276e3a4886f 19
mbed_official 525:c320967f86b9 20 static const ticker_interface_t us_interface = {
mbed_official 525:c320967f86b9 21 .init = us_ticker_init,
mbed_official 525:c320967f86b9 22 .read = us_ticker_read,
mbed_official 525:c320967f86b9 23 .disable_interrupt = us_ticker_disable_interrupt,
mbed_official 525:c320967f86b9 24 .clear_interrupt = us_ticker_clear_interrupt,
mbed_official 525:c320967f86b9 25 .set_interrupt = us_ticker_set_interrupt,
mbed_official 525:c320967f86b9 26 };
mbed_official 221:8276e3a4886f 27
mbed_official 525:c320967f86b9 28 static const ticker_data_t us_data = {
mbed_official 525:c320967f86b9 29 .interface = &us_interface,
mbed_official 525:c320967f86b9 30 .queue = &events,
mbed_official 525:c320967f86b9 31 };
mbed_official 525:c320967f86b9 32
mbed_official 525:c320967f86b9 33 const ticker_data_t* get_us_ticker_data(void)
mbed_official 525:c320967f86b9 34 {
mbed_official 525:c320967f86b9 35 return &us_data;
emilmont 4:c4bfb462ca53 36 }
emilmont 4:c4bfb462ca53 37
mbed_official 525:c320967f86b9 38 void us_ticker_irq_handler(void)
mbed_official 525:c320967f86b9 39 {
mbed_official 525:c320967f86b9 40 ticker_irq_handler(&us_data);
emilmont 4:c4bfb462ca53 41 }