PIC16F84A, MICROCHIP MICROCONTROLLER IC, 1.75 KB FLASH, 8-BIT

The PIC16F84A-20/P is a 8-bit 20MHz CMOS Flash/EEPROM-based Microcontroller. The EEPROM data memory is readable and writable during normal operation (full VDD range). This memory is not directly mapped in the register file space. Instead it is indirectly addressed through the special function registers. The PIC16F84A 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 72ms (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.