This system seems ideal for small chips like the ATmega328. Nil RTOS is extremely simple so it is great for new users.
I have written a number of examples and a guide, "Understanding the Examples", to help new users.
Here is the first example new users should try. It is included in the above download and requires about 2150 bytes of flash on an Uno.
Code: Select all
/*
* Example to demonstrate thread definition, semaphores, and thread sleep.
*/
#include <NilRTOS.h>
// The LED is attached to pin 13 on Arduino.
const uint8_t LED_PIN = 13;
// Declare a semaphore with an inital counter value of zero.
SEMAPHORE_DECL(sem, 0);
//------------------------------------------------------------------------------
/*
* Thread 1, turn the LED off when signaled by thread 2.
*/
// Declare a stack with 128 bytes beyond context switch and interrupt needs.
NIL_WORKING_AREA(waThread1, 128);
// Declare the thread function for thread 1.
NIL_THREAD(Thread1, arg) {
while (TRUE) {
// Wait for signal from thread 2.
nilSemWait(&sem);
// Turn LED off.
digitalWrite(LED_PIN, LOW);
}
}
//------------------------------------------------------------------------------
/*
* Thread 2, turn the LED on and signal thread 1 to turn the LED off.
*/
// Declare a stack with 128 bytes beyond context switch and interrupt needs.
NIL_WORKING_AREA(waThread2, 128);
// Declare the thread function for thread 2.
NIL_THREAD(Thread2, arg) {
pinMode(LED_PIN, OUTPUT);
while (TRUE) {
// Turn LED on.
digitalWrite(LED_PIN, HIGH);
// Sleep for 200 milliseconds.
nilThdSleepMilliseconds(200);
// Signal thread 1 to turn LED off.
nilSemSignal(&sem);
// Sleep for 200 milliseconds.
nilThdSleepMilliseconds(200);
}
}
//------------------------------------------------------------------------------
/*
* Threads static table, one entry per thread. A thread's priority is
* determined by its position in the table with highest priority first.
*
* These threads start with a null argument. A thread's name may also
* be null to save RAM since the name is currently not used.
*/
NIL_THREADS_TABLE_BEGIN()
NIL_THREADS_TABLE_ENTRY("thread1", Thread1, NULL, waThread1, sizeof(waThread1))
NIL_THREADS_TABLE_ENTRY("thread2", Thread2, NULL, waThread2, sizeof(waThread2))
NIL_THREADS_TABLE_END()
//------------------------------------------------------------------------------
void setup() {
// Start Nil RTOS.
nilSysBegin();
}
//------------------------------------------------------------------------------
// Loop is the idle thread. The idle thread must not invoke any
// kernel primitive able to change its state to not runnable.
void loop() {
// Not used.
}
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