Thread

Definition

Thread allows programming like with process-oriented programming languages. You can use While and Wait together with If and Case. Everything will be converted to if-structures afterwards. Thread also converts If, Case and signal assignments to work together with the procedure operations, because the If statement without Thread wouldn't wait for the While loop.

What you must look for

Sometimes a signal e.g. has to be set from '0' to '1', but if you write

En <= '0';
En <= '1';

both assignments will be executed in the same cycle and a different Process would not see the change of the state. What you can do is

En <= '0';
Step{ En <= '1'; }

This way En <= '1' is executed in a separate step.

Warning: Variables are created in the compilation process. Names of procedure operations in combination with numbers should not be used as names for own signals or variables.

Example

Process()
{
Thread
{
While(Btn = '0'){}
Led <= '1';
Wait(10000);
While(Btn = '1'){}
Wait(10000);
}
}
Last updated on by Hendrik Mennen