As we've seen throughout our projects, it can be helpful to watch the values associated with the PicoBoard sensors. In addition to selectively watching the sensor values, we can watch them all at one time.

From the Sensing palette, right-click on the sensor block and select the show ScratchBoard watcher option.

ScratchBoard was the predecessor to the PicoBoard. Selecting the ScratchBoard watcher places a monitor on the stage that shows all the sensors. Refer to the following screenshot:

As you look at the screenshot, you might think that some of the values are missing. The alligator clip sensors measure resistance, as the picture shows. However, the alligator clip sensors also report a true or false value to indicate when the clips touch. Why doesn't the ScratchBoard watcher show the Boolean value of the alligator clip sensors?

Have I led you enough yet? As you might guess, the Boolean values of the alligator clips are reported. We just have to interpret the true and false. In the screenshot, sensors A, B, and C report 100 while sensor D reports zero.

We know from our experiments that a value of 100 means no current is flowing. The alligator clips might as well be disconnected, and the answer to the question, "Is sensor A connected?" would be false. By contrast, a sensor value of zero indicates the current is flowing freely and that the clips are connected.