PIC16F87-ISLASHML datasheet(134/214 Pages) MICROCHIP

134 / 214 page

PIC16F87/88

DS30487B-page 132

Preliminary

 2003 Microchip Technology Inc.

15.2

RESET

The PIC16F87/88 differentiates between various kinds

of RESET:

• Power-on Reset (POR)

•MCLR Reset during normal operation

•MCLR Reset during SLEEP

• WDT Reset during normal operation

• WDT Wake-up during SLEEP

• Brown-out Reset (BOR)

Some registers are not affected in any RESET condi-

tion. Their status is unknown on POR and unchanged

in any other RESET. Most other registers are reset to a

“RESET state” on Power-on Reset (POR), on the

MCLR and WDT Reset, on MCLR Reset during

SLEEP, and Brown-out Reset (BOR). They are not

affected by a WDT wake-up, which is viewed as the

resumption of normal operation. The TO and PD bits

are set or cleared differently in different RESET situa-

tions, as indicated in Table 15-3. These bits are used in

software to determine the nature of the RESET. Upon

a POR, BOR, or wake-up from SLEEP, the CPU

requires approximately 5-10

µs to become ready for

code execution. This delay runs in parallel with any

other timers. See Table 15-4 for a full description of

RESET states of all registers.

A simplified block diagram of the on-chip RESET circuit

is shown in Figure 15-1.

FIGURE 15-1:

SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT

External

RESET

MCLR

VDD

OSC1

WDT

Module

VDD Rise

Detect

OST/PWRT

INTRC

WDT

Time-out

Power-on Reset

OST

10-bit Ripple Counter

PWRT

Chip_Reset

11-bit Ripple Counter

Reset

Enable OST

Enable PWRT

SLEEP

Brown-out

Reset

BOREN

31.25 kHz

PIC16F87-I/ML Datasheet(PDF) 134 Page - Microchip Technology

PIC16F87-I/ML Datasheet(HTML) 134 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL