The main features of PlC microcontroller

Photocoupler

1). Harvard bus structure PIC microcontroller uses a unique Harvard bus structure to separate the internal data bus from the instruction bus and use different instruction widths, which is convenient for the "flowing operation" of instructions. The so-called "flowing operation" refers to the instruction fetching of the next instruction while executing an instruction, which greatly improves the speed and efficiency of the CPU executing the instruction.

2). After the instruction single-byte data bus is separated from the instruction bus, it also creates conditions for the single-byte and single-cycle of all instructions of the PIC microcontroller. The address space of the program memory ROM and data memory RAM of the PIC microcontroller is independent of each other, and the two memory widths are different. This design not only ensures data security, but also improves the running speed and realizes single byte of all instructions. Turn.

3). The Reduced Instruction Set (RISC) technology PIC uses a reduced instruction set technique. Not only are all instructions single-byte instructions, but most instructions are single-cycle instructions, which helps to increase the speed of operation. The PlC series MCUs have different instruction byte widths. For example, the instruction byte of the PIC primary product is 12 bits, the instruction byte of the intermediate product is 14 bits, and the instruction byte of the advanced product is 16 bits. The data width is 8 bits.

4). The code compression rate of the instruction is high and the running speed is fast. Because the PIC microcontroller adopts the independent data bus and the Harvard bus structure of the instruction bus, the instruction has a single word length characteristic, and the instruction code bit number can be more than 8 data bits. Compared with the traditional 8-bit single-chip microcomputer with CISC (complex instruction set) and von Neumann structure, the code compression rate can reach 2:1 and the speed is increased by 4:1. For example: 1KB program memory space, for a microcontroller like MCS-51 can only store more than 500 instructions, and for PIC series microcontrollers, because of the very efficient use of memory space, store up to 1024 instructions.

5). Low power consumption PIC microcontroller adopts CMOS structure, and its power consumption is very low. It is one of the lowest power consumption microcontrollers in the world. Some of the special models of the MCU consume only 2 mA in 4MHz mode, while the power consumption in sleep mode can be as low as 1 microamp.

6). 1/0 port drive capability PIC microcontroller 1/0 port drive load is strong, each pin can drive 20/25mA load at maximum output, high level pull current output reaches 20mA, low power The flat sink current output is up to 25 mA. It can directly drive LEDs, optocouplers, small relays, etc. This greatly simplifies the control circuit due to its relatively high symmetrical high and low drive capability. However, it should be noted that the drive capability of each pin is 20/25mA, but the total drive capability of all ports of the chip should be less than 200mA.

7). On-chip resource-rich PIC series MCUs have integrated functions such as power-on reset circuits, I/O pin pull-up circuits, watchdog timers, etc., with comparison and capture functions. Timer/counter, multi-channel 10-bit ADC, SPI synchronous serial interface, IIC serial interface, etc., can minimize or eliminate external devices for "pure monolithic" applications. In this way, the manufacturing cost of the product is greatly reduced.

8). Easy to learn, develop, and cost-effective to use MicroChip's free integrated development environment (MPLAB-IDE) for program writing, simulation and online debugging, and MPLAB-IDE also supports third-party C compilers so that users can Using C language for development, greatly improving work efficiency. Under the amateur conditions, a PIC DEMO comprehensive test board and an ICD2 in-circuit debugger/program downloader can be used to complete the learning and development of the PIC microcontroller, and the cost is very low, only a few hundred dollars.

9). The program memory version is complete. Microchip's PIC microcontroller series offers a wide range of memory types and product packaging processes. It provides a full range of options for different test phases and different applications. .

EPROM type chip. It is a program memory chip that can be repeatedly erased/written. It needs to be irradiated under ultraviolet light for 20 minutes to erase its internal information content.

One-time programming (OTP) EPROM chip. Suitable for small batches of non-shaped products, users must complete the programming process by means of special equipment, which can reduce product cost.

Mask ROM type chip. Suitable for large-scale styling products, low cost.

EEPROM or Flash program memory. It is slightly more expensive than other products. The biggest advantage is that the program can be repeatedly erased/written online, which is especially suitable for the debugging of the development stage.