PIC (usually pronounced as ''"pick"'') is a family of

microcontroller A microcontroller (MCU for ''microcontroller unit'', often also MC, UC, or μC) is a small computer on a single VLSI integrated circuit (IC) chip. A microcontroller contains one or more CPUs ( processor cores) along with memory and programmabl ...

s made by Microchip Technology, derived from the PIC1650"PICmicro Family Tree", PIC16F Seminar Presentation originally developed by

General Instrument General Instrument (GI) was an American electronics manufacturer based in Horsham, Pennsylvania, specializing in semiconductors and cable television equipment. They formed in New York City in 1923 as an electronics manufacturer. During the 1950s, ...

's Microelectronics Division. The name PIC initially referred to ''Peripheral Interface Controller'',"MOS DATA 1976", General Instrument 1976 Databook and is currently expanded as ''Programmable Intelligent Computer''."1977 Data Catalog", Micro Electronics from General Instrument Corporation The first parts of the family were available in 1976; by 2013 the company had shipped more than twelve billion individual parts, used in a wide variety of

embedded system An embedded system is a computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is ''embedded ...

s. The PIC was originally intended to be used with the

General Instrument CP1600 The CP1600 is a 16-bit microprocessor created in a partnership between General Instrument and Honeywell, introduced in February 1975. It is one of the first single-chip 16-bit processors. The overall design bore a strong resemblance to the PDP-11. ...

, the first commercially available single-chip

16-bit 16-bit microcomputers are microcomputers that use 16-bit microprocessors. A 16-bit register can store 216 different values. The range of integer values that can be stored in 16 bits depends on the integer representation used. With the two ...

microprocessor A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circ ...

. The CP1600 had a complex bus that made it difficult to interface with, and the PIC was introduced as a companion device offering ROM for program storage,

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for temporary data handling, and a simple CPU for controlling the transfers. While this offered considerable power, GI's marketing was limited and the CP1600 was not a success. When the company spun off their chip division to form Microchip in 1985, sales of the CP1600 were all but dead. By this time, the PIC had formed a major market of its own, and it became one of the new company's primary products. Early models only had mask ROM for code storage, but with its spinoff it was soon upgraded to use

EPROM An EPROM (rarely EROM), or erasable programmable read-only memory, is a type of programmable read-only memory (PROM) chip that retains its data when its power supply is switched off. Computer memory that can retrieve stored data after a power s ...

and then

EEPROM EEPROM (also called E2PROM) stands for electrically erasable programmable read-only memory and is a type of non-volatile memory used in computers, usually integrated in microcontrollers such as smart cards and remote keyless systems, or ...

which made it much easier for end-users to program. All current models use

flash memory Flash memory is an electronic non-volatile computer memory storage medium that can be electrically erased and reprogrammed. The two main types of flash memory, NOR flash and NAND flash, are named for the NOR and NAND logic gates. Both use ...

for program storage, and newer models allow the PIC to reprogram itself. Since then the line has seen significant change; memory is now available in 8-bit, 16-bit, and, in latest models, 32-bit wide. Program instructions vary in bit-count by family of PIC, and may be 12, 14, 16, or 24 bits long. The instruction set also varies by model, with more powerful chips adding instructions for

digital signal processing Digital signal processing (DSP) is the use of digital processing, such as by computers or more specialized digital signal processors, to perform a wide variety of signal processing operations. The digital signals processed in this manner are ...

functions. The hardware implementations of PIC devices range from 6-pin SMD, 8-pin DIP chips up to 144-pin SMD chips, with discrete I/O pins, ADC and DAC modules, and communications ports such as

UART A universal asynchronous receiver-transmitter (UART ) is a computer hardware device for asynchronous serial communication in which the data format and transmission speeds are configurable. It sends data bits one by one, from the least signific ...

, I2C, CAN, and even USB. Low-power and high-speed variations exist for many types. The manufacturer supplies computer software for development known as MPLAB X, assemblers and C/C++ compilers, and programmer/debugger hardware under the MPLAB and PICKit series. Third party and some open-source tools are also available. Some parts have in-circuit programming capability; low-cost development programmers are available as well as high-volume production programmers. PIC devices are popular with both industrial developers and hobbyists due to their low cost, wide availability, large user base, an extensive collection of application notes, availability of low cost or free development tools, serial programming, and re-programmable flash-memory capability.

History

Original concept

The original PIC was intended to be used with General Instrument's new CP1600

central processing unit A central processing unit (CPU), also called a central processor, main processor or just processor, is the electronic circuitry that executes instructions comprising a computer program. The CPU performs basic arithmetic, logic, controlling, a ...

(CPU). In order to fit 16-bit

data bus In computer architecture, a bus (shortened form of the Latin '' omnibus'', and historically also called data highway or databus) is a communication system that transfers data between components inside a computer, or between computers. This ...

and

address bus In computer architecture, a bus (shortened form of the Latin '' omnibus'', and historically also called data highway or databus) is a communication system that transfers data between components inside a computer, or between computers. This e ...

into a then-standard 40-pin

dual inline package In microelectronics, a dual in-line package (DIP or DIL), is an electronic component package with a rectangular housing and two parallel rows of electrical connecting pins. The package may be through-hole mounted to a printed circuit board (P ...

(DIP) chip, the two busses shared the same set of 16 connection pins. In order to communicate with the CPU, devices had to watch other pins on the CPU to determine if the data on the bus was an address or data. Since only one of these was being presented at a time, the devices had to watch the bus to go into address mode, see if that address was part of its memory mapped input/output range, "latch" that address and then wait for the data mode to turn on and then read the value. Additionally, the 1600 used several external pins to select which device it was attempting to talk to, further complicating the interfacing. As interfacing devices to the 1600 could be complex, GI also released a series of support chips with all of the required circuitry built-in. These included keyboard drivers,

cassette deck A cassette deck is a type of tape machine for playing and recording audio cassettes that does not have a built-in power amplifier or speakers, and serves primarily as a transport. It can be a part of an automotive entertainment system, a part of ...

interfaces for storage, and a host of similar systems. For more complex systems, GI introduced the 8-bit PIC in 1975. The idea was that a device would use the PIC to handle all the interfacing with the host computer's CP1600, but also use its own internal processor to handle the actual device it was connected to. For instance, a floppy disk drive could be implemented with a PIC talking to the CPU on one side and the floppy disk controller on the other. In keeping with this idea, what would today be known as a

, the PIC included a small amount of

read-only memory Read-only memory (ROM) is a type of non-volatile memory used in computers and other electronic devices. Data stored in ROM cannot be electronically modified after the manufacture of the memory device. Read-only memory is useful for storing ...

(ROM) that would be written with the user's device controller code, and a separate

random access memory Random-access memory (RAM; ) is a form of computer memory that can be read and changed in any order, typically used to store working data and machine code. A random-access memory device allows data items to be read or written in almost the ...

(RAM) for buffering and working with data. These were connected separately, making the PIC a

Harvard architecture The Harvard architecture is a computer architecture with separate storage and signal pathways for instructions and data. It contrasts with the von Neumann architecture, where program instructions and data share the same memory and pathway ...

system with code and data being managed on separate internal pathways. In theory, the combination of 1600 CPU and PIC device controllers provided a very high-performance device control system, one that was similar in power and performance to the channel controllers see on

mainframe computer A mainframe computer, informally called a mainframe or big iron, is a computer used primarily by large organizations for critical applications like bulk data processing for tasks such as censuses, industry and consumer statistics, enterprise ...

s. In the floppy controller example, for instance, a single PIC could control the drive, provide a reasonable amount of buffering to improve performance, and then transfer data to and from the host computer using

direct memory access Direct memory access (DMA) is a feature of computer systems and allows certain hardware subsystems to access main system memory independently of the central processing unit (CPU). Without DMA, when the CPU is using programmed input/output, it is ...

(DMA) or through relatively simple code in the CPU. The downside to this approach was cost; while the PIC was not necessary for low-speed devices like a keyboard, many tasks would require one or more PICs to build out a complete system. While the design concept had a number of attractive features, General Instrument never strongly marketed the 1600, preferring to deal only with large customers and ignoring the low-end market. This resulted in very little uptake of the system, with the

Intellivision The Intellivision is a home video game console released by Mattel Electronics in 1979. The name is a portmanteau of "intelligent television". Development began in 1977, the same year as the launch of its main competitor, the Atari 2600. In 198 ...

being the only really widespread use with about three million units. When GI spun off its chip division to form Microchip Technology in 1985, production of the CP1600 ended. By this time, however, the PIC had developed a large market of customers using it for a wide variety of roles, and the PIC went on to become one of the new company's primary products.

After the 1600

In 1985, General Instrument sold their

microelectronics Microelectronics is a subfield of electronics. As the name suggests, microelectronics relates to the study and manufacture (or microfabrication) of very small electronic designs and components. Usually, but not always, this means micrometre- ...

division and the new owners cancelled almost everything which by this time was mostly out-of-date. The PIC, however, was upgraded with an internal

to produce a programmable channel controller. At the same time

Plessey The Plessey Company plc was a British electronics, defence and telecommunications company. It originated in 1917, growing and diversifying into electronics. It expanded after World War II by acquisition of companies and formed overseas compan ...

in the UK released NMOS processors numbered PIC1650 and PIC1655 based on the GI design, using the same instruction sets, either user mask programmable or versions pre-programmed for auto-diallers and keyboard interfaces. In 1998 Microchip introduced the PIC 16F84, a flash programmable and erasable version of its successful serial programmable PIC16C84. In 2001, Microchip introduced more Flash programmable devices, with full production commencing in 2002.}) or 8kB EEPROM in the 1886VE5U (''1886ВЕ5У''). The 1886VE5U (''1886ВЕ5У'') through 1886VE7U (''1886ВЕ7У'') are specified for the military temperature range of -60 °C to +125 °C. Hardware interfaces in the various parts include USB, CAN, I2C, SPI, as well as A/D and D/A converters. The 1886VE3U (''1886ВЕ3У'') contains a hardware accelerator for cryptographic functions according to GOST 28147-89. There are even radiation-hardened chips with the designations 1886VE8U (''1886ВЕ8У'') and 1886VE10U (''1886ВЕ10У'').

ELAN Microelectronics

ELAN Microelectronics Corp. in Taiwan make a line of microcontrollers based on the PIC16 architecture, with 13-bit instructions and a smaller (6-bit) RAM address space.

Holtek Semiconductor

Holtek Semiconductor make a large number of very cheap microcontrollers (as low as 8.5 ''cents'' in quantity) with a 14-bit instruction set strikingly similar to the PIC16.

Other manufacturers in Asia

Many ultra-low-cost OTP microcontrollers from Asian manufacturers, found in low-cost consumer electronics are based on the PIC architecture or modified form. Most clones only target the baseline parts (PIC16C5x/PIC12C50x). Microchip has attempted to sue some manufacturers when the copying is particularly egregious, without success.

References

External links

* .
Official Microchip website

PIC wifi projects website
{{DEFAULTSORT:PIC Microcontroller Microcontrollers Instruction set architectures Microchip Technology hardware