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10 years, 5 months ago.
Multiple threads
Hey guys , I am just trying to create a multi-thread program so I can send and receive information from my setup but for some reason the threads do not start or at least they dont seem to start.
Main.cpp
#include "mbed.h"
#include "BurstSPI.h"
#include "rtos.h"
Serial pc(USBTX, USBRX);
AnalogIn Vin(p18);
DigitalOut CS(p35);
DigitalOut LDR(p30);
int output=0x0000 ;
int next=1;
int i=0;
int data=0x0000;
BurstSPI device(p5, p6, p7); // mosi, miso, sclk
void outputSignal(void const *args)
{
device.format(16,0);
device.frequency(48000000);
device.setFormat();
LDR=1;
while(1) {
CS=0;
data=output|0x3000;
device.fastWrite(data);
device.clearRX();
CS=1;
if (next==1) {
output=output+0x000F;
} else if (next==2) {
output=output-0x000F;
}
if (output>=0x0fff) {
//output=0x0000;
next=2;
} else if (output<=0x0000) {
next=1;
}
i++;
LDR=0;
LDR=1;
}
}
//osThreadDef(led2_thread, osPriorityNormal, DEFAULT_STACK_SIZE);
///the main method
int main()
{
Thread testSignal(outputSignal);
//device.format(16,0);
// device.frequency(48000000);
// device.setFormat();
// LDR=1;
//
// while(1) {
// CS=0;
//
// data=output|0x3000;
// device.fastWrite(data);
// device.clearRX();
//
// CS=1;
// if (next==1) {
// output=output+0x000F;
// } else if (next==2) {
// output=output-0x000F;
// }
// if (output>=0x0fff) {
// //output=0x0000;
// next=2;
// } else if (output<=0x0000) {
// next=1;
// }
//
// i++;
// LDR=0;
// LDR=1;
}
}
1 Answer
10 years, 5 months ago.
As a start, I think you need to have an infinite loop inside main(). Otherwise, main(), and thus your program, exits immediately after starting your thread.
Something like:
int main() {
Thread testSignal(outputSignal);
while (true) {
}
}
The truth is , that this is the first thing I did myself , but it didnt seem to have any effect . But I tested it when the program itself was a bit different . I will try again .
posted by 03 Jan 2014Better then also disable the main thread, either by letting it wait on a signal it will never get, or just using a regular RTOS wait. Then it won't use CPU time on an infinite loop.
posted by 03 Jan 2014Seems like you might also want to have your outputSignal thread do a signal_wait() or wait().
posted by 03 Jan 2014I just tried the wait technique in my main loop . It seems to work now , I mean the second thread is running but the triangles I output are only there half of the time and the signal comes out really bad . For example half the waveform is there and the other half is like a shadow that is there for a very brief amount of time. Why is this ? I am using a wait without the while loop .
posted by 06 Jan 2014Correction , I was using wait right before the while loop that I assumed would never be reached because I used wait for ever . By removing the loop and leaving only wait for ever it seems that my main loop reaches the end and stops the whole thing again . How can I get the main loop to stop doing whatever its doing and concentrate on the new thread?
posted by 06 Jan 2014Progress . I managed to get a nice smooth signal using priorityHigh . Is there another way to make this work , just for future reference .
posted by 06 Jan 2014Excuse me there guys , If anybody still checks this question out . Can you explain what priorities really do ? I have two threads one with high priority and one with normal and the one with normal priority does not execute at all . I was expecting the lower priority thread to be slower than the high priority and instead I don't see it working at all .
posted by 07 Jan 2014