The types of devices such as microprocessors, microcontrollers, processors, and digital signal processors (DSP), amongst others, in a certain manner, are related to the same device – the ASIC (Application Specific Integrated Circuit). Each processing device executes instructions, following a determined program applied to the inputs, and shares architectural characteristics developed from the first microprocessors created in 1971. In the three decades after the development of the first microprocessor, huge developments and innovations have been made in this engineering field.

The programmable SoC (system-on-chip) concept started in 1972 with the 4-bit TMS1000 microcomputer developed by Texas Instruments (TI), and in those days it was ideal for applications such as calculators and ovens. This term was changed to Microcontroller Unit (MCU), which was more descriptive of a typical application. Nowadays, MCUs are at the heart of many physical systems, with higher levels of integration and processing power at lower power consumption.

The following list presents several qualities that define a microcontroller:

  1. Cost: Usually, the microcontrollers are high-volume low-costs devices;
  2. Clock frequency: Compared with other devices (microprocessors and DSPs), microcontrollers use a low clock frequency.
  3. Microcontrollers today can run up to 100 MHz/ 100 Million Instructions Per Second (MIPS)
  4. Power consumption: orders of magnitude lower than their DSP and MPU cousins;
  5. Bits: 4 bits (older devices) to 32 bits devices;
  6. Memory: Limited available memory, usually less than 1 MByte;
  7. Input/Output (I/O): Low to high (8-150) pin-out count.