Here's a simple tutorial to help you get started with GP3EZ. In traditional programming you learn
how to write "Hello World." This example will do the embedded system equivalent -- blinking a
light. Launch the program and select the COM port that your GP3 board connects to. In this
example, the port is COM5:
There is a single step already in place. Double click on it to bring up the step editor:
Note the step is enabled. That's good because if it isn't enabled, it won't have any effect when
you run the script, and GP3EZ will just skip it and go to the next step (if any). This step also has a
tag of "Start" by default. This is just a nickname you use to refer to the step. You could change if
you like. Steps don't have to have a tag if you don't need to refer to them in other parts of the
script. However, having unneeded tag names is harmless. The Notes field is a place for you to
make any comments or notes you need to remember what this step does. GP3EZ doesn't really
pay any attention to this. You can leave it blank or write as much as you like to document this
Note there are three tabs:
· Condition - What makes this step actually occur?
· Action - What does this step do when it activates?
· Next Step - Where to go next?
Normally, GP3EZ will start with the first step (this one) and move on to step #2, then step #3, and
so on. If this step is disabled, or the condition is not met, then step #2 will definitely be the next
step (assuming we make a step #2, which we will shortly). However, if the condition is met, the
next step will be determined by the "Next Step" tab. By default, however, it simply moves to the
next step. If there is no next step, the GP3EZ software halts the script execution.
Each step can have only one condition. By default the condition is "Always" which means this
step is always executed. If you need to wait for more than one condition, you'll have to break your
logic up into multiple steps.
Notice that you can wait for some conditions. For example, if you were waiting for a particular
input pattern, the behavior will change based on the "Wait for condition" check mark. If checked,
GP3EZ will wait on this step until the condition is met. If the the check mark is not checked,
GP3EZ will check the condition. If it is met, the action and the next step will take effect. If it is not
met, GP3EZ will just go on to the next step. Of course, not all conditions make sense to wait and
those conditions will gray out the wait check box.
To blink the onboard LED, we will make this step wait a short period of time and turn the LED on.
Then we'll make a second step which will wait a little while, turn the LED off, and go back to this
step (named Start, if you recall).
To complete this condition step, click on "After" and type in 250 in the milliseconds box. This will
delay for 1/4 second (there are 1000 milliseconds in a second).
Now click the Action tab. You can select more than one action at a time, but in this case we just
need one: the check box marked LED. This is a "three state" LED. By default it is grayed out (the
exact appearance depends on how your computer is set up). When grayed out, GP3EZ won't
change the state of the LED. Each time you click on the check box it will cycle between on, off,
and "gray." For this step, we want the check mark to be on:
That's it for this step. We need to make a second step, and you can do that by pressing the ->
button at the bottom of the window. This takes you to the "next" step, but since there isn't a next
step, the editor makes one.
Note the new step starts out with the Enabled check box turned off. So the first thing to do is click
that box to turn the step on. Also, notice the editor has put you back at the Condition tab. Click on
"After" again and enter 250 in the milliseconds box. This step doesn't need a tag. You can put
something in the notes if you wish, although this is just for your benefit, so you don't have to
change it if you don't want. Switch to the Action tab and select the LED check box to be off
(remember, it starts out in the "don't change" position, so you'll need to click the box to select the
off state. It should look something like this:
Finally, you need to select the Next Step tab. There are three buttons on this tab. The default
button, "Next," tells GP3EZ to just continue on with the next step when this step is done. That's
not what we want. The second button ("Goto") will let GP3EZ jump to another step. That's what
we want. We want to go to the "Start" step. Remember, this will only happen when the current
step's condition is true, but in this case, the condition is a timed wait, so it will eventually be true
You can click the Goto button or you can just drop down the list and pick Start from the list which
will automatically pick the Goto button at the same time:
Leave the "Bookmark Place" and "Loop" boxes unchecked. You'd check the bookmark box if you
wanted to call a subroutine that would later come back to the next step by using the "Last
Bookmark" button (if you don't know what that means, don't worry about it; you don't have to use
this feature). The loop box is used for repeating a sequence of steps a certain number of times.
Now you can press the Save button at the bottom of the window to return to the main window.
The script list should now look like:
If you changed the Notes on the steps you might have a slightly different appearance, of course.
The "<" to the left of the second step is a clue that the step doesn't continue on to the next step.
You might want to save the script using the "Save As..." button. If you have the GP3 connected
and powered on, pressing Run should show you a blinking LED! Congratulations! You just wrote
your first GP3EZ script.