This demo uses the mbed RTOS to run eight threads (including main). The threads are using different I/O devices on the application board. Several of the threads output to the LCD and an OS mutex lock is used to control access to the LCD and make the LCD thread safe.

Dependencies:   C12832_lcd LCD_fonts mbed-rtos mbed

Fork of lab1 by Peter Drescher

main.cpp

Committer:
dreschpe
Date:
2012-12-05
Revision:
3:3ec443c0842a
Parent:
2:a69c8c5f5b03
Child:
4:79863d2ea5a0

File content as of revision 3:3ec443c0842a:

// example to test the mbed Lab Board lcd lib with the mbed rtos
// Pot1 change the contrast
// Pot2 change the speed of the sin wave

#include "mbed.h"
#include "rtos.h"
#include "Small_6.h"
#include "Small_7.h"
#include "Arial_9.h"
#include "stdio.h"
#include "C12832_lcd.h"

// LCD object
C12832_LCD LCD;

AnalogIn Pot1(p19);
AnalogIn Pot2(p20);


// mutex to make the lcd lib thread save
Mutex lcd_mutex;

// Thread 1
// print counter into first line and wait for 1 s
void thread1(void const *args)
{
    int i;
    while(true) {       // thread loop
        lcd_mutex.lock();
        LCD.locate(0,0);
        LCD.set_font((unsigned char*) Small_6);
        LCD.printf("Thread1 count: %d",i);
        lcd_mutex.unlock();
        i++;
        Thread::wait(1000);
    }
}

// Thread 2
// print counter into third line and wait for 0,5s
void thread2(void const *args)
{
    int k;
    while(true) {       // thread loop
        lcd_mutex.lock();
        LCD.locate(0,20);
        LCD.set_font((unsigned char*) Arial_9);
        LCD.printf("Thread 2 count : %d",k);
        lcd_mutex.unlock();
        k++;
        Thread::wait(500); // wait 0.5s
    }
}

// Thread 3
// print a sin function in a small window
// the value of pot 1 change the speed of the sinwave
void thread3(void const *args)
{
    int i,k,v;
    double s,a;
    k = 1;
    lcd_mutex.lock();
    LCD.rect(89,0,127,17,1);
    lcd_mutex.unlock();
    while(true) {       // thread loop
        v = Pot1.read_u16();  // get value of pot 1
        lcd_mutex.lock();
        for (i=90; i<127; i++) {           
            s = 8 * sin((long double)(i+k) /5);   // pixel to print  
            a = 8 * sin((long double)(i+k-1) /5); // old pixel to erase
            LCD.pixel(i,9 + (int)a ,0);           // erase pixel  
            LCD.pixel(i,9 + (int)s ,1);           // print pixel  
        }
        LCD.copy_to_lcd();  // LCD.pixel do not update the lcd 
        lcd_mutex.unlock();
        k++;
        Thread::wait(v/100);   // value of pot1 / 100
    }
}

// Thread 4
// input pot 2 and change the contrast of lcd
void thread4(void const *args)
{
    int k;
    while(true) {         // thread loop
    k = Pot2.read_u16();  // get the value of poti 2
    k = k >> 10;          // we need only 6 bit for contrast
     lcd_mutex.lock();
    LCD.set_contrast(k);
     lcd_mutex.unlock();
    Thread::wait(500);    // wait 0.5s
}
}


// print the actual contrast 
int main()
{
    int j;
    LCD.cls();
  
    Thread t1(thread1); //start thread1
    Thread t2(thread2); //start thread2
    Thread t3(thread3); //start thread3
    Thread t4(thread4); //start thread4

    while(true) {       // main is the next thread
        lcd_mutex.lock();
        LCD.locate(0,9);
        LCD.set_font((unsigned char*) Small_7);
        j = LCD.get_contrast();    // read the actual contrast
        LCD.printf("contrast : %d",j);
        lcd_mutex.unlock();
        Thread::wait(500);   // wait 0.5s
    }

}