DSPIC30F6010A MICROCHIP [Microchip Technology], DSPIC30F6010A Datasheet - Page 157

• Manufacturer Part Number: DSPIC30F6010A
• Description: High-Performance, 16-bit Digital Signal Controllers
• Manufacturer: MICROCHIP [Microchip Technology]

21.2.8
A write to the OSCCON register is intentionally made
difficult because it controls clock switching and clock
scaling.
To write to the OSCCON low byte, the following code
sequence must be executed without any other
instructions in between:
Byte write is allowed for one instruction cycle. Write the
desired value or use bit manipulation instruction.
To write to the OSCCON high byte, the following
instructions must be executed without any other
instructions in between:
Byte write is allowed for one instruction cycle. Write the
desired value or use bit manipulation instruction.
21.3
The dsPIC30F differentiates between various kinds of
Reset:
a)
b)
c)
d)
e)
f)
g)
h)
FIGURE 21-2:
© 2011 Microchip Technology Inc.
Byte Write 0x46 to OSCCON low
Byte Write 0x57 to OSCCON low
Byte Write 0x78 to OSCCON high
Byte Write 0x9A to OSCCON high
Power-on Reset (POR)
MCLR Reset during normal operation
MCLR 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)
MCLR
V
DD
Reset
Instruction
RESET
PROTECTION AGAINST
ACCIDENTAL WRITES TO OSCCON
Illegal Opcode/
Uninitialized W Register
Trap Conflict
Brown-out
V
Sleep or Idle
Module
Detect
DD
WDT
Reset
RESET SYSTEM BLOCK DIAGRAM
Rise
BOREN
Glitch Filter
Digital
POR
BOR
dsPIC30F6010A/6015
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
are used in software to determine the nature of the
Reset.
A block diagram of the on-chip Reset circuit is shown in
Figure 21-2.
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.
21.3.1
A power-on event will generate an internal POR pulse
when a V
at the POR circuit threshold voltage (V
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
nominally 10 μs and ensures that the device bias
circuits are stable. Furthermore, a user selected power-
up time-out (T
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
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 21-3 through Figure 21-5.
DD
POR: POWER-ON RESET
rise is detected. The Reset pulse will occur
PWRT
POR
) is applied. The T
S
R
+ T
PWRT
Q
Table
. When these delays
DS70150E-page 157
PWRT
21-5. These bits
POR
SYSRST
POR
), which is
parameter
, which is