DSPIC30F4011_10 Datasheet, PDF (151/238 Pages) Microchip Technology – High-Performance, 16-Bit Digital Signal Controllers

21.0 SYSTEM INTEGRATION
Note:
This data sheet summarizes features of
this group of dsPIC30F devices and is not
intended to be a complete reference
source. For more information on the CPU,
peripherals, register descriptions and
general device functionality, refer to the
dsPIC30F Family Reference Manual
(DS70046). For more information on the
device instruction set and programming,
refer to the “16-bit MCU and DSC
Reference Manual” (DS70157).
There are several features intended to maximize
system reliability, minimize cost through elimination of
external components, provide power-saving operating
modes and offer code protection:
• Oscillator Selection
• Reset
- Power-on Reset (POR)
- Power-up Timer (PWRT)
- Oscillator Start-up Timer (OST)
- Programmable Brown-out Reset (BOR)
• Watchdog Timer (WDT)
• Power-Saving Modes (Sleep and Idle)
• Code Protection
• Unit ID Locations
• In-Circuit Serial Programming (ICSP)
dsPIC30F devices have a Watchdog Timer which is
permanently enabled via the Configuration bits, or can
be software controlled. It runs off its own RC oscillator for
added reliability. There are two timers that offer neces-
sary delays on power-up. One is the Oscillator Start-up
Timer (OST), intended to keep the chip in Reset until the
crystal oscillator is stable. The other is the Power-up
Timer (PWRT), which provides a delay on power-up
only, designed to keep the part in Reset while the power
supply stabilizes. With these two timers on-chip, most
applications need no external Reset circuitry.
Sleep mode is designed to offer a very low-current
Power-Down mode. The user can wake-up from Sleep
through external Reset, Watchdog Timer wake-up or
through an interrupt. Several oscillator options are also
made available to allow the part to fit a wide variety of
applications. In the Idle mode, the clock sources are
still active, but the CPU is shut off. The RC oscillator
option saves system cost, while the LP crystal option
saves power.
dsPIC30F4011/4012
21.1 Oscillator System Overview
The dsPIC30F oscillator system has the following
modules and features:
• Various external and internal oscillator options as
clock sources
• An on-chip PLL to boost internal operating
frequency
• A clock switching mechanism between various
clock sources
• Programmable clock postscaler for system power
savings
• A Fail-Safe Clock Monitor (FSCM) that detects
clock failure and takes fail-safe measures
• Oscillator Control register (OSCCON)
• Configuration bits for main oscillator selection
Table 21-1 provides a summary of the dsPIC30F
oscillator operating modes. A simplified diagram of the
oscillator system is shown in Figure 21-1.
Configuration bits determine the clock source upon
Power-on Reset (POR) and Brown-out Reset (BOR).
Thereafter, the clock source can be changed between
permissible clock sources. The OSCCON register
controls the clock switching and reflects system clock
related status bits.
© 2010 Microchip Technology Inc.
DS70135G-page 151