Lancaster University / mbed-src

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api/DigitalOut.h@641:be9b2017785a, 2016-07-13 (annotated)

Committer:
LancasterUniversity
Date:
Wed Jul 13 12:52:54 2016 +0100
Revision:
641:be9b2017785a
Parent:
455:8bc3a354916d 
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
bogdanm 13:0645d8841f51 1 /* mbed Microcontroller Library
bogdanm 13:0645d8841f51 2 * Copyright (c) 2006-2013 ARM Limited
bogdanm 13:0645d8841f51 3 *
bogdanm 13:0645d8841f51 4 * Licensed under the Apache License, Version 2.0 (the "License");
bogdanm 13:0645d8841f51 5 * you may not use this file except in compliance with the License.
bogdanm 13:0645d8841f51 6 * You may obtain a copy of the License at
bogdanm 13:0645d8841f51 7 *
bogdanm 13:0645d8841f51 8 * http://www.apache.org/licenses/LICENSE-2.0
bogdanm 13:0645d8841f51 9 *
bogdanm 13:0645d8841f51 10 * Unless required by applicable law or agreed to in writing, software
bogdanm 13:0645d8841f51 11 * distributed under the License is distributed on an "AS IS" BASIS,
bogdanm 13:0645d8841f51 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
bogdanm 13:0645d8841f51 13 * See the License for the specific language governing permissions and
bogdanm 13:0645d8841f51 14 * limitations under the License.
bogdanm 13:0645d8841f51 15 */
bogdanm 13:0645d8841f51 16 #ifndef MBED_DIGITALOUT_H
bogdanm 13:0645d8841f51 17 #define MBED_DIGITALOUT_H
bogdanm 13:0645d8841f51 18
bogdanm 13:0645d8841f51 19 #include "platform.h"
bogdanm 13:0645d8841f51 20 #include "gpio_api.h"
bogdanm 13:0645d8841f51 21
bogdanm 13:0645d8841f51 22 namespace mbed {
bogdanm 13:0645d8841f51 23
bogdanm 13:0645d8841f51 24 /** A digital output, used for setting the state of a pin
bogdanm 13:0645d8841f51 25 *
bogdanm 13:0645d8841f51 26 * Example:
bogdanm 13:0645d8841f51 27 * @code
bogdanm 13:0645d8841f51 28 * // Toggle a LED
bogdanm 13:0645d8841f51 29 * #include "mbed.h"
bogdanm 13:0645d8841f51 30 *
bogdanm 13:0645d8841f51 31 * DigitalOut led(LED1);
bogdanm 13:0645d8841f51 32 *
bogdanm 13:0645d8841f51 33 * int main() {
bogdanm 13:0645d8841f51 34 * while(1) {
bogdanm 13:0645d8841f51 35 * led = !led;
bogdanm 13:0645d8841f51 36 * wait(0.2);
bogdanm 13:0645d8841f51 37 * }
bogdanm 13:0645d8841f51 38 * }
bogdanm 13:0645d8841f51 39 * @endcode
bogdanm 13:0645d8841f51 40 */
bogdanm 13:0645d8841f51 41 class DigitalOut {
bogdanm 13:0645d8841f51 42
bogdanm 13:0645d8841f51 43 public:
bogdanm 13:0645d8841f51 44 /** Create a DigitalOut connected to the specified pin
bogdanm 13:0645d8841f51 45 *
bogdanm 13:0645d8841f51 46 * @param pin DigitalOut pin to connect to
bogdanm 13:0645d8841f51 47 */
mbed_official 212:34d62c0b2af6 48 DigitalOut(PinName pin) : gpio() {
mbed_official 113:65a335a675de 49 gpio_init_out(&gpio, pin);
mbed_official 113:65a335a675de 50 }
mbed_official 113:65a335a675de 51
mbed_official 113:65a335a675de 52 /** Create a DigitalOut connected to the specified pin
mbed_official 113:65a335a675de 53 *
mbed_official 113:65a335a675de 54 * @param pin DigitalOut pin to connect to
mbed_official 113:65a335a675de 55 * @param value the initial pin value
mbed_official 113:65a335a675de 56 */
mbed_official 212:34d62c0b2af6 57 DigitalOut(PinName pin, int value) : gpio() {
mbed_official 113:65a335a675de 58 gpio_init_out_ex(&gpio, pin, value);
bogdanm 13:0645d8841f51 59 }
bogdanm 13:0645d8841f51 60
bogdanm 13:0645d8841f51 61 /** Set the output, specified as 0 or 1 (int)
bogdanm 13:0645d8841f51 62 *
bogdanm 13:0645d8841f51 63 * @param value An integer specifying the pin output value,
bogdanm 13:0645d8841f51 64 * 0 for logical 0, 1 (or any other non-zero value) for logical 1
bogdanm 13:0645d8841f51 65 */
bogdanm 13:0645d8841f51 66 void write(int value) {
bogdanm 13:0645d8841f51 67 gpio_write(&gpio, value);
bogdanm 13:0645d8841f51 68 }
bogdanm 13:0645d8841f51 69
bogdanm 13:0645d8841f51 70 /** Return the output setting, represented as 0 or 1 (int)
bogdanm 13:0645d8841f51 71 *
bogdanm 13:0645d8841f51 72 * @returns
bogdanm 13:0645d8841f51 73 * an integer representing the output setting of the pin,
bogdanm 13:0645d8841f51 74 * 0 for logical 0, 1 for logical 1
bogdanm 13:0645d8841f51 75 */
bogdanm 13:0645d8841f51 76 int read() {
bogdanm 13:0645d8841f51 77 return gpio_read(&gpio);
bogdanm 13:0645d8841f51 78 }
bogdanm 13:0645d8841f51 79
mbed_official 455:8bc3a354916d 80 /** Return the output setting, represented as 0 or 1 (int)
mbed_official 455:8bc3a354916d 81 *
mbed_official 455:8bc3a354916d 82 * @returns
mbed_official 455:8bc3a354916d 83 * Non zero value if pin is connected to uc GPIO
mbed_official 455:8bc3a354916d 84 * 0 if gpio object was initialized with NC
mbed_official 455:8bc3a354916d 85 */
mbed_official 455:8bc3a354916d 86 int is_connected() {
mbed_official 455:8bc3a354916d 87 return gpio_is_connected(&gpio);
mbed_official 455:8bc3a354916d 88 }
mbed_official 455:8bc3a354916d 89
bogdanm 13:0645d8841f51 90 #ifdef MBED_OPERATORS
bogdanm 13:0645d8841f51 91 /** A shorthand for write()
bogdanm 13:0645d8841f51 92 */
bogdanm 13:0645d8841f51 93 DigitalOut& operator= (int value) {
bogdanm 13:0645d8841f51 94 write(value);
bogdanm 13:0645d8841f51 95 return *this;
bogdanm 13:0645d8841f51 96 }
bogdanm 13:0645d8841f51 97
bogdanm 13:0645d8841f51 98 DigitalOut& operator= (DigitalOut& rhs) {
bogdanm 13:0645d8841f51 99 write(rhs.read());
bogdanm 13:0645d8841f51 100 return *this;
bogdanm 13:0645d8841f51 101 }
bogdanm 13:0645d8841f51 102
bogdanm 13:0645d8841f51 103 /** A shorthand for read()
bogdanm 13:0645d8841f51 104 */
bogdanm 13:0645d8841f51 105 operator int() {
bogdanm 13:0645d8841f51 106 return read();
bogdanm 13:0645d8841f51 107 }
bogdanm 13:0645d8841f51 108 #endif
bogdanm 13:0645d8841f51 109
bogdanm 13:0645d8841f51 110 protected:
bogdanm 13:0645d8841f51 111 gpio_t gpio;
bogdanm 13:0645d8841f51 112 };
bogdanm 13:0645d8841f51 113
bogdanm 13:0645d8841f51 114 } // namespace mbed
bogdanm 13:0645d8841f51 115
bogdanm 13:0645d8841f51 116 #endif