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Despite being 40 years old, 8051 microcontrollers can still serve useful roles in modern systems.

But integrating 8051s in today's systems with their de facto standard AMBA® buses, wider datapaths, and shared memories can seem impossible. Yet it can be done. Here we take a look at the challenges, and how to overcome them.

Why Use 8051s?

First, why should you even consider using an 8-bit 8051-compatible microcontroller?

A primary reason is to more efficiently handle useful functions in certain ultra-low-power systems, such as for edge-device Internet of Things applications. Consider:

• The 8-bit 8051 will be considerably smaller than any 32-bit counterpart. Less silicon area means less power leakage, a critical factor for devices with long idle times.
• Code for the 8051’s 8-bit Complex Instruction Set Architecture (CISC) can be smaller and more dense than that for today’s more popular Reduced Instruction Set Architecture (RISC) processors. This means smaller memories—further reducing area-dependent leakage— and also, significantly, fewer energy-consuming instruction fetches to complete a given task.
• Developer training and 8051 deployment and testing are simplified through a vast, robust ecosystem of 8051 development and debugging tools, software stacks, example code, and general support.
• There are numerous thoroughly proven 8051 microcontroller IP cores available that integrate peripherals—SPI, I2C, UARTs, etc.—in a package that can be reliably dropped into many systems.

With these advantages, why aren’t 8051s used as often as they once were?