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/lp_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
mbed_official 525:c320967f86b9 1 /* mbed Microcontroller Library
mbed_official 525:c320967f86b9 2 * Copyright (c) 2015 ARM Limited
mbed_official 525:c320967f86b9 3 *
mbed_official 525:c320967f86b9 4 * Licensed under the Apache License, Version 2.0 (the "License");
mbed_official 525:c320967f86b9 5 * you may not use this file except in compliance with the License.
mbed_official 525:c320967f86b9 6 * You may obtain a copy of the License at
mbed_official 525:c320967f86b9 7 *
mbed_official 525:c320967f86b9 8 * http://www.apache.org/licenses/LICENSE-2.0
mbed_official 525:c320967f86b9 9 *
mbed_official 525:c320967f86b9 10 * Unless required by applicable law or agreed to in writing, software
mbed_official 525:c320967f86b9 11 * distributed under the License is distributed on an "AS IS" BASIS,
mbed_official 525:c320967f86b9 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
mbed_official 525:c320967f86b9 13 * See the License for the specific language governing permissions and
mbed_official 525:c320967f86b9 14 * limitations under the License.
mbed_official 525:c320967f86b9 15 */
mbed_official 525:c320967f86b9 16 #include "lp_ticker_api.h"
mbed_official 525:c320967f86b9 17
mbed_official 525:c320967f86b9 18 #if DEVICE_LOWPOWERTIMER
mbed_official 525:c320967f86b9 19
mbed_official 525:c320967f86b9 20 static ticker_event_queue_t events;
mbed_official 525:c320967f86b9 21
mbed_official 525:c320967f86b9 22 static const ticker_interface_t lp_interface = {
mbed_official 525:c320967f86b9 23 .init = lp_ticker_init,
mbed_official 525:c320967f86b9 24 .read = lp_ticker_read,
mbed_official 525:c320967f86b9 25 .disable_interrupt = lp_ticker_disable_interrupt,
mbed_official 525:c320967f86b9 26 .clear_interrupt = lp_ticker_clear_interrupt,
mbed_official 525:c320967f86b9 27 .set_interrupt = lp_ticker_set_interrupt,
mbed_official 525:c320967f86b9 28 };
mbed_official 525:c320967f86b9 29
mbed_official 525:c320967f86b9 30 static const ticker_data_t lp_data = {
mbed_official 525:c320967f86b9 31 .interface = &lp_interface,
mbed_official 525:c320967f86b9 32 .queue = &events,
mbed_official 525:c320967f86b9 33 };
mbed_official 525:c320967f86b9 34
mbed_official 525:c320967f86b9 35 const ticker_data_t* get_lp_ticker_data(void)
mbed_official 525:c320967f86b9 36 {
mbed_official 525:c320967f86b9 37 return &lp_data;
mbed_official 525:c320967f86b9 38 }
mbed_official 525:c320967f86b9 39
mbed_official 525:c320967f86b9 40 void lp_ticker_irq_handler(void)
mbed_official 525:c320967f86b9 41 {
mbed_official 525:c320967f86b9 42 ticker_irq_handler(&lp_data);
mbed_official 525:c320967f86b9 43 }
mbed_official 525:c320967f86b9 44
mbed_official 525:c320967f86b9 45 #endif