2 The Smart “Things” in IoT
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2.4.2 Three Main Types of Microcontrollers
The three well-known microcontrollers currently on the market include PIC MCUs,
AVR MCUs, and ARM MCUs [6].
2.4.2.1 Peripheral Interface Controller (PIC) Microcontrollers
These microcontrollers are a group of specialized microcontroller chips created in
the early 1990s by Microchip Technology in Chandler, Arizona. PIC microcontrollers are created using a Harvard architecture and are utilized in a variety of device
families. Basic and midrange families utilize 8-bit data memory, while higher-end
device families utilize 16-bit data memory. In 2007, Microchip began producing
32-bit microcontrollers using the MIPS32 Core. The MIPS32 core is a reduced
instruction set architecture (RISC) developed by MIPS Technologies, Inc. PICs
instruction sets can vary from 35 instructions on the low end to 80+ instructions
for higher-end PICs.
2.4.2.2 AVR Microcontrollers
The AVR microcontroller was initially created in 1996 at Atmel Corporation by
Vegard Wollan and Alf-Egil Bogen. The AVR is an acronym standing for AlfEgil Bogen and Vegard Wollan’s RISC processor. These microcontrollers utilize
a modified Harvard RISC architecture with divided instruction and data memory
buses. The AVR performance is generally higher in comparison to a PIC. AVR
microcontrollers can be divided into four categories:
• TinyAVR – Smaller in size with less memory; utilized for simple applications:
– .5–32 KB program memory
– 6–32 pins
– Limited peripherals
• MegaAVR – Highly popular as these provide a larger memory (up to 256 KB) and
more in-built peripherals; utilized for modestly to more complex applications:
– 4–256 KB program memory
– 28–100 pins
– Larger instruction set (e.g., multiply instructions)
– Extensive peripheral set
• XmegaAVR – 8-/16-bit AVR XMEGA is utilized in highly complicated or
commercial applications that require a larger program memory and higher
speed:
– Compatible with tinyAVR and megaAVR devices
– 16–384 KB program memory
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2.4.2 Three Main Types of Microcontrollers
The three well-known microcontrollers currently on the market include PIC MCUs,
AVR MCUs, and ARM MCUs [6].
2.4.2.1 Peripheral Interface Controller (PIC) Microcontrollers
These microcontrollers are a group of specialized microcontroller chips created in
the early 1990s by Microchip Technology in Chandler, Arizona. PIC microcontrollers are created using a Harvard architecture and are utilized in a variety of device
families. Basic and midrange families utilize 8-bit data memory, while higher-end
device families utilize 16-bit data memory. In 2007, Microchip began producing
32-bit microcontrollers using the MIPS32 Core. The MIPS32 core is a reduced
instruction set architecture (RISC) developed by MIPS Technologies, Inc. PICs
instruction sets can vary from 35 instructions on the low end to 80+ instructions
for higher-end PICs.
2.4.2.2 AVR Microcontrollers
The AVR microcontroller was initially created in 1996 at Atmel Corporation by
Vegard Wollan and Alf-Egil Bogen. The AVR is an acronym standing for AlfEgil Bogen and Vegard Wollan’s RISC processor. These microcontrollers utilize
a modified Harvard RISC architecture with divided instruction and data memory
buses. The AVR performance is generally higher in comparison to a PIC. AVR
microcontrollers can be divided into four categories:
• TinyAVR – Smaller in size with less memory; utilized for simple applications:
– .5–32 KB program memory
– 6–32 pins
– Limited peripherals
• MegaAVR – Highly popular as these provide a larger memory (up to 256 KB) and
more in-built peripherals; utilized for modestly to more complex applications:
– 4–256 KB program memory
– 28–100 pins
– Larger instruction set (e.g., multiply instructions)
– Extensive peripheral set
• XmegaAVR – 8-/16-bit AVR XMEGA is utilized in highly complicated or
commercial applications that require a larger program memory and higher
speed:
– Compatible with tinyAVR and megaAVR devices
– 16–384 KB program memory