Microcontroller Tips: Trade-offs in Choosing 8-bit vs.16- and 32-bit Architectures

by Scott Thornton

Besides the advantage of higher performance in performing calculations and faster data transfers, what are the advantages of working with an MCU that has a larger bus width?

MCUs with higher data bus widths enjoy higher performance in terms of faster operations, often more powerful development tools, more features, and better power efficiency. In general, lower bus widths limit perfprinted-circuit-board-1539113_1920ormance in exchange for a slight cost benefit to a project's budget. In this article, consider all discussion below to include 16-bits somewhere in between 8-bits and 32-bits. However, 16-bits will lean towards 32-bits in what it can offer in performance benefits, how it’s programmed, debugged, in cost, in labor, and…in general.

The number of cycles increases as the bus width decreases: Lower bit widths require more cycles to complete larger computations. It takes more cycles for an 8-bit MCU to complete a large computation than MCUs with a 16-bit data bus width. Using a 32-bit MCU can reduce computational cycles down further. Besides speed in completing calculations and in data throughput, a 32-bit MCU can handle operations in one cycle that an 8-bit MCU would need many cycles to complete. If there’s an interrupt or failure in the middle of a transfer, the 8-bit MCU has a greater chance of not completing the task, with several cycles required, versus a 32-bit MCU that completes the same task in one cycle. If computational speed and throughput are important...Read more on Microcontroller Tips

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