Datasheet

Table Of Contents
© 2011 Microchip Technology Inc. DS70143E-page 153
dsPIC30F6011A/6012A/6013A/6014A
20.4 Reset
The dsPIC30F differentiates between various kinds of
Reset:
Power-on Reset (POR)
•M
CLR Reset during normal operation
•M
CLR Reset during Sleep
Watchdog Timer (WDT) Reset (during normal
operation)
Programmable Brown-out Reset (BOR)
RESET Instruction
Reset caused by trap lockup (TRAPR)
Reset caused by illegal opcode, or by using an
uninitialized W register as an Address Pointer
(IOPUWR)
Different registers are affected in different ways by
various Reset conditions. Most registers are not
affected by a WDT wake-up, since this is viewed as the
resumption of normal operation. Status bits from the
RCON register are set or cleared differently in different
Reset situations, as indicated in Table 20-5. These bits
are used in software to determine the nature of the
Reset.
A block diagram of the on-chip Reset circuit is shown in
Figure 20-2.
A MCLR
noise filter is provided in the MCLR Reset
path. The filter detects and ignores small pulses.
Internally generated Resets do not drive MCLR
pin low.
20.4.1 POR: POWER-ON RESET
A power-on event will generate an internal POR pulse
when a V
DD rise is detected. The Reset pulse will occur
at the POR circuit threshold voltage (VPOR), which is
nominally 1.85V. The device supply voltage character-
istics must meet specified starting voltage and rise rate
requirements. The POR pulse will reset a POR timer
and place the device in the Reset state. The POR also
selects the device clock source identified by the
oscillator configuration fuses.
The POR circuit inserts a small delay, T
POR, which is
nominally 10 μs and ensures that the device bias
circuits are stable. Furthermore, a user selected power-
up time-out (T
PWRT) is applied. The TPWRT parameter
is based on device Configuration bits and can be 0 ms
(no delay), 4 ms, 16 ms or 64 ms. The total delay is at
device power-up T
POR + TPWRT. When these delays
have expired, SYSRST
will be negated on the next
leading edge of the Q1 clock, and the PC will jump to
the Reset vector.
The timing for the SYSRST
signal is shown in
Figure 20-3 through Figure 20-5.
FIGURE 20-2: RESET SYSTEM BLOCK DIAGRAM
S
R
Q
MCLR
VDD
VDD Rise
Detect
POR
SYSRST
Sleep or Idle
Brown-out
Reset
BOREN
RESET
Instruction
WDT
Module
Digital
Glitch Filter
BOR
Trap Conflict
Illegal Opcode/
Uninitialized W Register