Designers are often faced with a decision on which microcontroller variety to use, and are left to parse out the differences between 8-, 16-, and 32-bit MCUs. 16-bit MCU was previously favored in some applications due to shortcomings of the two “extremes” in 8-bit and 32-bit varieties.
However, as vendors continue to expand their portfolios, 16-bit options seem to be used less and less. Given that trend, it’s important to outline several clear distinctions and application uses for designers when choosing between 8- bit vs. a 32-bit, as well as outlining how advances in both portfolios have eliminated the need for the 16-bit MCU.
As referenced above, vendors such as Atmel continue to develop broad 8-bit AVR MCU portfolios that deliver 16-bit performance. These 8-bit AVR products include industry-leading low-power features with smart peripherals, security blocks and high-speed features that push the boundaries of 8-bit MCUs.
Many engineers choose to use 8-bit AVR MCUs where they would have previously relied on a 16-bit MCU because the specific applications require an MCU that has scalable system performance with reduced cost, smaller size, greater flash memory and lower power. In fact, many companies today deliver microcontrollers that fulfill historic 16-bit application requirements—standby, sleep for lower power consumption, powerful and efficient peripherals, and smaller footprint – but with an 8-bit microcontroller.
Speaking more broadly, one of the key trends for the 8-bit market has been the integration of a rich peripheral set on the MCU. Previously, these blocks—including USB, LCD control, 12-bit ADC and DAC and other functions—were often all included in external components. Atmel, for instance, has solved this by developing a variety of 8-bit products that allow customers to support a wide range of applications and maximize code re-use and design efficiency.
When discussing larger scale applications, such as automotive, industrial, biometric, audio, communication and Web servers, designers were previously left with a tough decision, as these applications require extremely robust computing performance, but demand low power consumption—constraining designers to rely on 16-bit MCUs in an attempt to satisfy both needs.
However, with the integrated functionality of a deep sleep mode in the latest 32-bit MCU families, and more efficient 32-bit proprietary and ARM CPUs, designers are now able to select a 32-bit MCU and use the additional performance while still reaping the low-power performance and smaller footprint previously associated with 16-bit varieties.
Where just a few years ago, high development tool cost was a barrier to utilizing 32 bit-MCUs, low-cost 32-bit tools have emerged that allow ease-of-entry into the 32-bit workspace. Additionally, 32-bit MCUs also include more memory and interfaces such as high-speed USB for the system designer—creating fewer design barriers and spurring greater adoption.
For both 8- and 32-bit MCUs, power consumption is a key determinant, and that concern has led to greater innovation. Some vendors address the power consumption issue for both 8- and 32-bit markets using the same technology.
For instance, Atmel offers a proprietary low-power technology to address the issue with its picoPower for all 8- and 32-bit MCUs. This technology enables Atmel products to achieve the industry’s lowest power consumption and power-down sleep. These low-power technologies address the concerns of longer battery life and lower power consumption for various applications in ZigBee, power tools, medical, board controllers, networking, metering, optical transceivers, motor control, white goods and any battery-powered products.
Both 8- and 32-bit MCUs have greatly expanded the range of applications they can support—providing designers with greater selection and flexibility. Both markets have grown quickly and encroached into the 16-bit space, but by meeting low power and scalability needs, designers are left with superior choices and clearer delineation of application use.
Andreas Eieland is Senior Product Marketing Manager for Flash Microcontrollers at Atmel. Prior to this position, Mr. Eieland worked as an AVR Product Marketing Manager and Applications Engineer at Atmel’s AVR Products Center. He holds a Master of Science degree from the Norwegian University of Science and Technology.