In 1971, the MCU was born. The full name of MCU is micro control unit, which means that with the emergence and development of large-scale integrated circuits, the computer's CPU, RAM, ROM, timer and various I/O interfaces are integrated on a chip to form a chip-level computer. .
It is precisely because of the flexibility of the MCU that it is widely used in the fields of consumer electronics, industrial control, automotive electronics and communications.
With the continuous development of MCU, from the previous 1-bit, 4-bit, 8-bit, 16-bit, to the current 32-bit or even 64-bit. Among the wide variety of MCUs, 8-bit and 32-bit MCUs have gradually become the mainstream in the current market, and the 16-bit MCUs caught in them seem to be in the same position.
Excellent 8-bit and 32-bit MCUs
When discussing the changes of 8-bit, 16-bit, and 32-bit MCUs, let's first understand what a "bit" is. The "bit" here refers to the "word length" of the MCU, that is, the length of the data involved in the operation in one operation. According to general theory, the larger the number of digits, the higher the computing efficiency and the stronger the performance. But this is a theoretical result. In the actual selection of MCU, factors that need to be considered include frequency, power consumption, price, etc.
Forty years ago, Intel launched an 8-bit MCU with limited functions, the MCS-51, which is the predecessor of the currently known "51 microcontroller". Within a few years of its introduction, the 8051 design led the embedded market, with multiple manufacturers introducing their own versions of the 8051. The MCS-51 system single-chip microcomputer is popular because of its reliable performance, simple and practical, and high cost performance, and is known as "the most classic single-chip microcomputer".
As more designs are added, this growth in architecture is also adding to numerous end products. The Atmel 8051 also became one of the best sellers of the 8-bit Intel MCS-51. Later, the number of MCU bits gradually increased, and 16-bit and 32-bit MCUs appeared in the market, so many people believed that 8-bit MCUs would gradually disappear over time.
Back to ten years ago, some experts in the industry said: "8-bit MCU is dead". When Freescale launched the Kinetis L series, it also called the "8-bit MCU terminator", threatening to eat the 16-bit MCU market first, and then squeeze out the 8-bit MCU share.
However, ten years have passed, and the reality seems to be worse than expected. 8-bit MCU still occupies a place in the market. From the official website of the industry distributor, we can see that there are currently nearly 50,000 different MCUs available worldwide. Among them, the number of 8-bit MCUs available is the largest and accounts for the largest proportion.
What keeps 8-bit MCUs alive?
On the one hand, the most prominent features of 8-bit MCU are low power consumption and low cost. In terms of overall power consumption, although a 32-bit MCU can run four times faster, a slower 8-bit MCU will always consume more power than a faster 32-bit MCU. In many embedded designs, 8-bit MCU has the advantage of being easier to design than 32-bit, and the software and hardware following the 8-bit architecture are simpler than 32-bit. And in terms of price, as the pressure on development costs increases, embedded system brand manufacturers will be more penny-pinching about the overall bill of materials (BOM) cost, and the cheap 8-digit price still has a market advantage.
Therefore, an 8-bit MCU is sufficient in some cases. With the advantages of ultra-low cost and simple design, 8-bit MCUs are active in the market, especially in the Chinese market.
On the other hand, manufacturers have not reduced their efforts to develop 8-bit MCUs. To meet the demand for 8-bit microcontrollers (MCUs), Microchip launched 5 new series, more than 60 devices, 8-bit PIC and AVR microcontrollers; BYD further expanded the lineup of automotive-grade 8-bit general-purpose MCU series , newly launched the car-grade 8-bit MCU BS9000AMXX series, etc.
This is why 8-bit MCUs are still active in the market after many years.
Excluding the 8-bit MCU, the current market share is the 32-bit MCU. According to IC Insights forecast, the 32-bit market share in the global MCU market will reach 67% in 2022.
In fact, it is reasonable for 32-bit MCUs to achieve such a proportion. Although 8-bit MCUs are widely used and low in cost, their overall performance is still limited. In high-end and complex scenarios, a 32-bit MCU with higher performance is often required. For example, in automotive electronics, 32-bit MCUs are mainly used for high-end function control such as vehicle control, smart meters, multimedia information systems, power systems, and assisted driving.
And the intelligentization of automobiles has greatly boosted the demand for 32-bit MCUs. According to the McClean report, more than three-quarters of automotive MCU sales in 2021 will come from 32-bit MCUs, which are expected to reach about US$5.83 billion. More and more MCU companies are planning to focus on the development of high-end 32-bit products.
In addition, with the application of high-efficiency and advanced manufacturing processes, the cost of 32-bit MCUs has been effectively reduced. With the breakthrough of the $1 mark in 2015 as a turning point, the price of 32-bit MCUs continues to approach the prices of traditional 16-bit MCUs and high-end 8-bit MCUs.
The combination of price reduction and performance improvement makes 32-bit MCU an irresistible attraction. In many traditional 32-bit products, 32-bit MCUs can be seen one after another, such as watches or home appliances. (such as a refrigerator), etc.
Why do 16-bit MCUs exist?
With 32-bit MCUs continuing to drop in price and 8-bit MCUs simple and durable, 16-bit MCUs have become the product with the lowest shipment ratio, and many companies have even removed 16-bit MCUs from their plans.
In fact, the 16-bit MCU also had a glorious moment. For quite a long period of time, the industry has long had low expectations for single-chip microcomputers. 8-bit computers are enough to use, and 16-bit and 32-bit are considered to be excess performance.
Later, 8-bit MUCs became more and more powerful, but due to limited processing power and addressable memory, there are inherent limitations in performance, so that 8-bit microcontrollers are usually not selected for high-performance applications. Systems based on 32-bit cores tend to be overkill for these applications, especially if they result in unnecessary power consumption.
The 16-bit MCU sits in the middle of the 8-bit and 32-bit cores, while being as power-efficient as a simple single-supply 8-bit MCU, while offering some of the performance and memory advantages of the 32-bit core. And, if the application does not require many simultaneous threads and the memory requirements are not too high, a 16-bit MCU can provide an appropriate level of performance with significant power savings.
Therefore, for many low-power, medium-performance battery-operated embedded applications, developers at the time preferred to choose a suitable 16-bit MCU rather than a 32-bit core.
In 1996, Texas Instruments launched a 16-bit ultra-low-power mixed-signal processor, the MSP430 series single-chip microcomputer, mainly because it integrated many analog circuits, digital circuits and microprocessors for practical application requirements. on a chip to provide a "monolithic" solution. Because of its low power consumption, fast speed, few instructions, and flexible assembly language, it is well received in the industry.
In 2005, Microchip announced that the 16-bit MCU will be one of the future development priorities. The PIC24F, PIC24H in the PIC24 series, and the second dsPIC33F series with DSP control function, a total of 49 different models of 16-bit MCU.
The 16-bit MCU surpassed the 8-bit MCU for the first time in 2011, becoming the product with the largest shipment volume; in 2011, the shipment volume increased by 23%, and in 2012 it continued to grow by 11%; in 2013, the 16-bit MCU shipment volume continued An increase of 6% to 6.7 billion pieces.
Until 2015, global 32-bit MCU shipments exceeded the sum of 4/8-bit MCU and 16-bit MCU shipments, and 16-bit MCUs ushered in decline.
Will 16-bit MCU gradually withdraw from the market？
Judging from the current mainstream applications, 4-bit and 16-bit MCUs have almost disappeared, and the entire application market is basically divided by 8-bit and 32-bit MCUs. The 64-bit MCU market is still in its infancy, and most of it is used in high-end workstations, multimedia interactive systems, and advanced terminals.
Even in the current popular automotive field, 16-bit MCUs, which are mainly used for underbody, such as engines, electronic brakes, suspension systems and other power and transmission systems, are also increasing in performance and memory capacity of 8-bit MCUs and the number of 32-bit MCUs. Constantly growing and throwing away armor and armor. However, in some key applications of the power transmission system, 16-bit MCUs are still useful.
However, 16-bit MCUs may not have to. It has higher performance than 8-bit and faster response time than 32-bit. If it can strive to compete with 8-bit products in terms of price and approach 32-bit in terms of performance, then 16-bit MCU will also embark on a unique development path.
For example, Renesas launched the RL78/G15. The RL78 is a 16-bit single-chip microcomputer with a main frequency of 16MHz. It clearly pointed out that this MCU hopes to seize the 8-bit MCU market and use it to "replace" the 8-bit MCU.
The RL78/G23 is compatible with Renesas' current general-purpose RL78 MCUs (such as the RL78/G13), while improving power consumption performance to meet the needs of battery-powered applications. In addition, in response to market demand, the on-chip flash memory capacity has been increased to 768KB, and the on-chip peripheral functions have been greatly expanded, thereby improving security and reducing bill of materials (BOM) costs while increasing functions.
With the above features, the new RL78/G23 is ideal for various applications that require a balance between power consumption and cost, including home electronics, remote controls, and IoT end devices such as sensors.
In addition, ROHM Semiconductor is also constantly upgrading the technology of 16-bit MCU to cope with the diversification of MCU demand in the home appliance market. ROHM's 16-bit MCU is developed on the basis of 8-bit MCU, including two models ML620100 and ML620500, the former focuses on anti-interference, and the latter focuses on low power consumption.
Perhaps under the diversified market demand, 16-bit MCU can occupy its own place in the market.
