PIC24FJ64GA705 Datasheet, PDF (82/412 Pages) –

PIC24FJ256GA705 FAMILY
7.1 Special Function Register Reset
States
Most of the Special Function Registers (SFRs) associ-
ated with the PIC24F CPU and peripherals are reset to a
particular value at a device Reset. The SFRs are
grouped by their peripheral or CPU function and their
Reset values are specified in each section of this manual.
The Reset value for each SFR does not depend on the
type of Reset, with the exception of four registers. The
Reset value for the Reset Control register, RCON, will
depend on the type of device Reset. The Reset value
for the Oscillator Control register, OSCCON, will
depend on the type of Reset and the programmed
values of the FNOSC<2:0> bits in the FOSCSEL Flash
Configuration Word (see Table 7-2). The RCFGCAL
and NVMCON registers are only affected by a POR.
7.2 Device Reset Times
The Reset times for various types of device Reset are
summarized in Table 7-3. Note that the Master Reset
Signal, SYSRST, is released after the POR delay time
expires.
The time at which the device actually begins to execute
code will also depend on the system oscillator delays,
which include the Oscillator Start-up Timer (OST) and
the PLL lock time. The OST and PLL lock times occur
in parallel with the applicable SYSRST delay times.
The Fail-Safe Clock Monitor (FSCM) delay determines
the time at which the FSCM begins to monitor the system
clock source after the SYSRST signal is released.
7.3 Brown-out Reset (BOR)
PIC24FJ256GA705 family devices implement a BOR
circuit that provides the user with several configuration
and power-saving options. The BOR is controlled by the
BOREN<1:0> (FPOR<1:0>) Configuration bits.
When BOR is enabled, any drop of VDD below the BOR
threshold results in a device BOR. Threshold levels are
described in Section 32.1 “DC Characteristics”.
7.4 Clock Source Selection at Reset
If clock switching is enabled, the system clock source at
device Reset is chosen, as shown in Table 7-2. If clock
switching is disabled, the system clock source is always
selected according to the Oscillator Configuration bits.
For more information, refer to the “dsPIC33/PIC24
Family Reference Manual”, “Oscillator” (DS39700).
TABLE 7-2:
Reset Type
POR
BOR
MCLR
WDTO
SWR
OSCILLATOR SELECTION vs.
TYPE OF RESET (CLOCK
SWITCHING ENABLED)
Clock Source Determinant
FNOSC<2:0> Configuration bits
(FOSCSEL<2:0>)
COSC<2:0> Control bits
(OSCCON<14:12>)
DS30010118B-page 82
 2016 Microchip Technology Inc.