Argus Brown / Mbed OS signals-main-thread

A demonstration that uses multiple signals from the main thread

This example shows how to use multiple signals from the main thread in mbed-os.

The sample sets up two Tickers to generate periodic interrupts. Each ticker sets a signal during an interrupt.

osSignalWait(signal, timeout) is used to wait for an event. Set signal to 0 to exit on any signal or set signal to a mask value to only exit if all of the signals are set.

main.cpp@1:907cf114c40c, 2016-09-08 (annotated)

Committer:
argusbrown
Date:
Thu Sep 08 21:33:41 2016 +0000
Revision:
1:907cf114c40c
Parent:
0:677614c5f014 
Removed one of the osSignalWait sections to make the demo clearer.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
argusbrown 0:677614c5f014 1 #include "mbed.h"
argusbrown 0:677614c5f014 2
argusbrown 0:677614c5f014 3 Serial pc(USBTX, USBRX);
argusbrown 0:677614c5f014 4 Ticker tick1;
argusbrown 0:677614c5f014 5 Ticker tick2;
argusbrown 0:677614c5f014 6 DigitalOut led1(LED_RED,true);
argusbrown 0:677614c5f014 7 DigitalOut led2(LED_GREEN,true);
argusbrown 0:677614c5f014 8 osThreadId mainThread;
argusbrown 0:677614c5f014 9
argusbrown 0:677614c5f014 10 void interrupt1()
argusbrown 0:677614c5f014 11 {
argusbrown 0:677614c5f014 12 osSignalSet(mainThread, 0x1);
argusbrown 0:677614c5f014 13 }
argusbrown 0:677614c5f014 14
argusbrown 0:677614c5f014 15 void interrupt2()
argusbrown 0:677614c5f014 16 {
argusbrown 0:677614c5f014 17 osSignalSet(mainThread, 0x2);
argusbrown 0:677614c5f014 18 }
argusbrown 0:677614c5f014 19
argusbrown 0:677614c5f014 20 int main()
argusbrown 0:677614c5f014 21 {
argusbrown 0:677614c5f014 22 pc.baud(115200);
argusbrown 0:677614c5f014 23 pc.printf("Init\n\r");
argusbrown 0:677614c5f014 24
argusbrown 0:677614c5f014 25 // Get the id of the main thread
argusbrown 0:677614c5f014 26 mainThread = Thread::gettid();
argusbrown 0:677614c5f014 27
argusbrown 0:677614c5f014 28 tick1.attach(&interrupt1, 1.0); // setup ticker to call interrupt1 every 1.0 seconds
argusbrown 1:907cf114c40c 29 tick2.attach(&interrupt2, 2.4); // setup ticker to call interrupt2 every 1.0 seconds
argusbrown 0:677614c5f014 30
argusbrown 0:677614c5f014 31 while (true) {
argusbrown 0:677614c5f014 32 // If the event mask is set to 0, then any signal will exit the wait.
argusbrown 0:677614c5f014 33 // If nothing happens for 10 seonds, timeout
argusbrown 0:677614c5f014 34 // Internaly the code is doing something like this:
argusbrown 1:907cf114c40c 35 // if (signal1 | signal2) then exit wait
argusbrown 0:677614c5f014 36 osEvent v = osSignalWait(0, 10000);
argusbrown 1:907cf114c40c 37
argusbrown 1:907cf114c40c 38 // Use this form to wait for both events
argusbrown 1:907cf114c40c 39 // Internaly the code is doing something like this:
argusbrown 1:907cf114c40c 40 // if ((signal1 | signal2) & 0x3 == 0x3) then exit wait
argusbrown 1:907cf114c40c 41 //osEvent v = osSignalWait(0x3, 10000);
argusbrown 1:907cf114c40c 42
argusbrown 0:677614c5f014 43 pc.printf("Wait1 exit. Status: 0x%x\n",(int) v.status);
argusbrown 0:677614c5f014 44
argusbrown 0:677614c5f014 45 if (v.status == osEventSignal) {
argusbrown 0:677614c5f014 46 pc.printf("Signals Event1 Caught: 0x%x\n",(int) v.value.signals);
argusbrown 0:677614c5f014 47
argusbrown 0:677614c5f014 48 // Tick1 timeout
argusbrown 0:677614c5f014 49 if (v.value.signals & 0x1) {
argusbrown 0:677614c5f014 50 led1 = !led1;
argusbrown 0:677614c5f014 51 pc.printf("Event1 0x1\n");
argusbrown 0:677614c5f014 52 }
argusbrown 0:677614c5f014 53
argusbrown 0:677614c5f014 54 // Tick2 timeout
argusbrown 0:677614c5f014 55 if (v.value.signals & 0x2) {
argusbrown 0:677614c5f014 56 led2 = !led2;
argusbrown 0:677614c5f014 57 pc.printf("Event1 0x2\n");
argusbrown 0:677614c5f014 58 }
argusbrown 0:677614c5f014 59
argusbrown 1:907cf114c40c 60 }
argusbrown 1:907cf114c40c 61
argusbrown 0:677614c5f014 62 }
argusbrown 0:677614c5f014 63 }