Special Microcontroller Functions

There are numerous special I/O functions found on modern microcontrollers. In a nutshell they include:

Hardware interrupts Interrupts are special inputs that provide a means to get the attention of the microcontroller. When the interrupt is triggered, the controller can temporarily suspend normal program execution and run a special subprogram.

Analog/mixed-signal (A/MS) This refers to inputs (and often outputs) that can handle analog or digital signals, under software guidance. Many microcontrollers are designed to handle both analog and digital signals on the same chip and even mix and match analog/digital on the same pins of the device. This gives you more flexibility.

External reset This is an input that resets the microcontroller so it clears any data in memory and restarts its program.

Switch debouncer This feature cleans up the signal transition when a mechanical switch (push button, magnetic reed, etc.) opens or closes. Without a debouncer, the microcontroller may see numerous signal transitions and could interpret each one as a separate switch state. With the debouncer, the control electronics sees just a single transition.

Input pull-up Pull-up (and/or pull-down) resistors are required for many kinds of inputs to control electronics. If the source of the input is not actively generating a signal, the input could “float” and therefore confuse the robot’s brain. The pull-up/pull-down resistors, which may be built into a microcontroller and activated via software, prevent this floating from occurring. When the resistor function is not built into the chip, you may need to add the resistors to the circuit yourself. This increases the complexity of the circuit and adds to its cost.