So far, so good. Electronic circuits can be very interesting and, while they seem very complex, often we find that the working can be very simple. In the previous section, we interfaced one sensor at a time. We can go ahead and interface multiple sensors, but we are limited by the number of GPIOs that are present. We have also seen that some sensors such as ultrasonic sensors may use more than one GPIO pin for their working. This further reduces the number of sensors that we can interface with the microcontroller. Once we move on to more complex circuits, we will also realize that the wiring can be really messy and if a problem occurs then finding what's wrong becomes one tedious task.

Now, there is an even bigger problem that we face while designing robotic systems and that's the problem of timing—all the work done in a system has to be synchronized. Most of the systems are currently sequential in nature, as in the output of one unit becomes the input of another:

Now...