ZBasic Language Reference
65
ZBasic Microcontrollers
Dim taskStack(1 to 80) as Byte
Sub Main()
CallTask "MyTask", taskStack
Do
Debug.Print "Hello from Main"
Call Delay(1.0)
Loop
End Sub
Sub MyTask()
Do
Debug.Print "Hello from MyTask"
Call Delay(2.0)
Loop
End Sub
This simple program has two tasks: Main and MyTask. The Main task is created automatically for you
and its task stack is automatically allocated all of the remaining User RAM after explicitly defined
variables are allocated. In contrast, additional tasks such as MyTask have to be explicitly invoked using
the CallTask statement and each task’s stack must also be explicitly allocated, for example by defining
a Byte array as shown above. A task is said to be “active” if it has been invoked by CallTask and has
not yet terminated. Both of the tasks above never terminate so they are always active. The example
below shows a situation where a task terminates.
Dim taskStack(1 to 50) as Byte
Sub Main()
CallTask "MyTask", taskStack
Do
Debug.Print "Hello from Main"
Call Delay(1.0)
Loop
End Sub
Sub MyTask()
Dim i as Integer
For i = 1 to 5
Debug.Print "Hello from MyTask"
Call Delay(2.0)
Next i
End Sub
In this example, the task MyTask will output the message 5 times and then terminate. After the task
terminates, its task stack could be used for another task. It is important to note that tasks cannot use the
same task stack if they will be active at the same time.
The examples above were chosen because they clearly illustrate, when executed, that the separate tasks
experience interleaved execution. A more realistic example is shown (necessarily incompletely) below.
Dim taskStack(1 to 50) as Byte
Sub Main()
CallTask "MyTask", taskStack
Do
<other-important-stuff>
Loop
End Sub
Sub MyTask()
' set the interval timer to 5 seconds
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