Microchip has introduced six different lines of 8-bit MCUs over the years:
1. PIC12XXX: 8-pin, 12- or 14-bit instruction format
2. PIC14000: 28-pin, 14-bit instruction format (same as PIC16XX)
3. PIC16C5X: 12-bit instruction format
4. PIC16CXX: 14-bit instruction format
5. PIC17: 16-bit instruction format
6. PIC18: 16-bit instruction format
Each line of the PIC MCUs support different number of instructions with slightly different instruction formats and different design in their peripheral functions. This makes products designed with a different family of PIC MCUs incompatible. The members of the PIC18 family share the same instruction set and the same peripheral function design and provide from eight to more than 80 signal pins. This makes it possible to upgrade the PIC18-based product without changing the MCU family. One of the design goals of the PIC18 MCU is to eliminate the design flaws of other earlier MCU families and provide a better upgrade path to other families of MCUs. In terms of cost, the PIC18 MCUs are not more expensive than those in other families with similar capability.
The PIC18 MCUs provide the following peripheral functions:
1. Parallel 1/0 ports
2. Timer functions, including counters, input capture, output compare, real-time interrupt, and watchdog timer
3. Pulse width modulation (PWM)
4. SPI and J2C serial interface
5. Universal Synchronous/Asynchronous Receiver Transmitter (USART)
6. A/D converter with 10-bit resolution
7. Analog comparator
8. Low-power operation mode
9. SRAMandEEPROM
10. EPROM or flash memory
11. Controller Area Network (CAN)
From 2003, 40 devices in the PIC18 family have been produced, and more devices have been introduced in the coming few years. All these MCUs implement 77 instructions. Among them, 73 instructions are 16 bits, and the remaining four are 32 bits.
Applications:
PIC18 perfectly fits many uses, from automotive industries and controlling home appliances to industrial instruments, remote sensors, electrical door locks and safety devices. It is also ideal for smart cards as well as for battery supplied devices because of its low consumption. EEPROM memory makes it easier to apply microcontrollers to devices where permanent storage of various parameters is needed (codes for transmitters, motor speed, receiver frequencies, etc.). Low cost, low consumption, easy handling and flexibility make PIC18 applicable even in areas where microcontrollers had not previously been considered (example: timer functions, interface replacement in larger systems, co-processor applications, etc.)
In System Programmability of this chip (along with using only two pins in data transfer) makes possible the flexibility of a product, after assembling and testing have been completed. This capability can be used to create assembly-line production, to store calibration data available only after final testing, or it can be used to improve programs on finished products.
Comments
Post a Comment