pic
Open categories: embedded, integrated circuits, microcontrollers, digital circuits, automatic control
Introduction to PIC series microcontrollers
1 , Introduction
According to statistics, my country's annual capacity of single-chip microcomputers has reached 100-300 million pieces, and is growing at an annual rate of approximately 16%, but my country's share of the world market is less than 1%. This shows that the application of microcontrollers has just started in our country and has broad prospects. Cultivating microcontroller application talents, especially popularizing microcontroller knowledge among engineering and technical personnel, has important practical significance.
Today, there are a wide variety of microcontroller manufacturers with different product performances. Which model should we choose for specific situations? First, let’s clarify two concepts: centralized instruction set (CISC) and reduced instruction set (RISC). The data lines and instruction lines of a single-chip microcomputer using a CISC structure are time-division multiplexed, which is the so-called von Neumann structure. It has rich instructions and strong functions, but fetching instructions and data cannot be performed at the same time, the speed is limited, and the price is high. The data lines and instruction lines of a microcontroller using a RISC structure are separated, which is the so-called Harvard structure. This allows instruction fetching and data fetching to be carried out at the same time, and because the general instruction line is wider than the data line, its instructions contain more processing information than similar CISC microcontroller instructions, and the execution efficiency is higher and the speed is faster. At the same time, most of the instructions of this kind of microcontroller are single bytes, and the space utilization of the program memory is greatly improved, which is conducive to the realization of ultra-miniaturization. MCUs that belong to the CISC structure include Motorola and M68HC series, Atmel's AT89 series, Taiwan's Winbond W78 series, Pilips' PCF80C51 series from the Netherlands, etc.; those that belong to the RISC structure include the Intel8051 series, Microchip's PIC series, and Zilog's Z86 series. , Atmel's AT90S series, South Korea's Samsung KS57C series 4-bit microcontrollers, Taiwan's Elan's EM-78 series, etc. Generally speaking, small household appliances with relatively simple control relationships can use RISC microcontrollers; situations with more complex control relationships, such as communication products and industrial control systems, should use CISC microcontrollers. However, the rapid improvement of RISC microcontrollers has made its leaders no less effective in situations with complex control relationships.