PIC16F688T-I/ST View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC16F688T-I/ST

14-Pin Flash-Based, 8-Bit CMOS Microcontrollers with nanoWatt Technology

Microchip Technology 

PIC16F688

11.2 Reset

The PIC16F688 differentiates between various kinds of

Reset:

a) Power-on Reset (POR)

b) WDT Reset during normal operation

c) WDT Reset during Sleep

d) MCLR Reset during normal operation

e) MCLR Reset during Sleep

f) Brown-out Reset (BOR)

Some registers are not affected in any Reset condition;

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

• MCLR Reset

• MCLR Reset during Sleep

• WDT Reset

• Brown-out Reset (BOR)

They are not affected by a WDT wake-up since this is

viewed as the resumption of normal operation. TO and

PD bits are set or cleared differently in different Reset

situations, as indicated in Table 11-2. These bits are

used in software to determine the nature of the Reset.

See Table 11-4 for a full description of Reset states of

all registers.

A simplified block diagram of the On-Chip Reset Circuit

is shown in Figure 11-1.

The MCLR Reset path has a noise filter to detect and

ignore small pulses. See Section 14.0 “Electrical

Specifications” for pulse width specifications.

FIGURE 11-1:

SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT

External

Reset

MCLR/VPP pin

VDD

Sleep

WDT

Module

WDT

Time-out

Reset

VDD Rise

Detect

Power-on Reset

Brown-out(1)

Reset

BOREN

SBOREN

OSC1/

CLKI pin

OST/PWRT

OST

10-bit Ripple Counter

PWRT

LFINTOSC

11-bit Ripple Counter

S

Chip_Reset

R

Q

Note 1: Refer to the Configuration Word register (Register 11-1).

Enable PWRT

Enable OST

DS41203D-page 112

© 2007 Microchip Technology Inc.

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