The PIC 16x8x Family

The PIC16F8X family of devices are CMOS (Complementary Metal Oxide Semiconductor) microcontrollers consisting of the PIC16F83, PIC16C83, PIC16F84, PIC16C84, PIC16LCR8X and PIC16LF8X types. CMOS technology offers a number of advantages over other technologies. For example, CMOS circuits consume very little power, operate over quite a wide voltage range and are quite forgiving of bad layout and electrical noise. The PIC16X8X is available in an 18 pin IC package. The IC consists of two pins for the power supply, two pins for the oscillator, OSC1 and OSC2, a pin for the master reset clear line MCLR and 13 pins for input/output (I/O) ports, RA0 to RA4 and RB0 to RB7.

All PICmicro™ microcontrollers employ an advanced RISC architecture. PIC16F8X devices have enhanced core features, eight-level deep stack, and multiple internal and external interrupt sources. The separate instruction and data buses of the Harvard architecture allow a 14-bit wide instruction word with a separate 8-bit wide data bus. The two stage instruction pipeline allows all instructions to execute in a single cycle, except for program branches (which require two cycles). A total of 35 instructions (reduced instruction set) are available. Additionally, a large register set is used to achieve a very high performance level.  PIC16F8X microcontrollers typically achieve a 2:1 code compression and up to a 4:1 speed improvement (at 20MHz) over other 8-bit microcontrollers in their class. The PIC16F8X has up to 68 bytes of RAM, 64 bytes of Data EEPROM memory, and 13 I/O pins. A timer/counter is also available. The PIC16CXX family has special features to reduce external components, thus reducing cost, enhancing system reliability and reducing power consumption. There are four oscillator options, of which the single pin RC oscillator provides a low-cost solution, the LP oscillator minimizes power consumption, XT is a standard crystal, and the HS is for High Speed crystals. The SLEEP (power-down) mode offers power saving. The user can wake the chip from sleep through several external and internal interrupts and resets. A highly reliable Watchdog Timer with its own on-chip RC oscillator provides protection against software lock-up.

Features of PIC16x8x:

What Dose the F,C,CR & LF in the PIC device number mean

• F, as in PIC16F84. These devices have Flash program memory and operate over the standard voltage range.

• LF, as in PIC16LF84. These devices have Flash program memory and operate over an extended voltage range.

• CR, as in PIC16CR83. These devices have ROM program memory and operate over the standard voltage range.

• LCR, as in PIC16LCR84. These devices have ROM program memory and operate over an extended voltage range.

Special Features of the PIC 16f84

What sets a microcontroller apart from other processors are special circuits to deal with the needs of real time applications. The PIC16F8X has a host of such features intended to maximize system reliability, minimize cost through elimination of external components, provide power saving operating modes and offer code protection. These features are:

• OSC Selection

• Reset

  - Power-on Reset (POR)

  - Power-up Timer (PWRT)

  - Oscillator Start-up Timer (OST)

• Interrupts

• Watchdog Timer (WDT)

• SLEEP

• Code protection

• ID locations

• In-circuit serial programming

The PIC16F8X has a Watchdog Timer which can be shut off only through configuration bits. It runs off its own RC oscillator for added reliability. There are two timers that offer necessary delays on power-up. One is the Oscillator Start-up Timer (OST), intended to keep the chip in reset until the crystal oscillator is stable. The other is the Power-up Timer (PWRT), which provides a fixed delay of 72 ms (nominal) on power-up only. This
design keeps the device in reset while the power supply stabilizes. With these two timers on-chip, most applications need no external reset circuitry. SLEEP mode offers a very low current power-down mode. The user can wake-up from SLEEP through external reset, Watchdog Timer time-out or through an interrupt. Several oscillator options are provided to allow the part to fit the application. The RC oscillator option saves system cost while the LP crystal option saves power. A set of configuration bits are used to select the various options.