Clock
Signals/Connections
2
-5
2.3
Clock
2.4
Phase Lock Loop (PLL)
Table 2-4. Clock Signals
Signal
Name
Type
State During
Reset
Signal Description
EXTAL
Input
Input
External Clock/Crystal Input—Interfaces the internal crystal oscillator
input to an external crystal or an external clock.
XTAL
Output
Chip-driven
Crystal Output—Connects the internal crystal oscillator output to an
external crystal. If an external clock is used, leave XTAL unconnected.
Table 2-5. Phase Lock Loop Signals
Signal Name
Type
State During
Reset
Signal Description
PCAP
Input
Input
PLL Capacitor—Connects an off-chip capacitor to the PLL filter. See
the DSP56303 Technical Data sheet to determine the correct PLL
capacitor value. Connect one capacitor terminal to PCAP and the
other terminal to V
CCP
.
If the PLL is not used, PCAP can be tied to V
CC
, GND, or left floating.
CLKOUT
Output
Chip-driven
Clock Output—Provides an output clock synchronized to the internal
core clock phase.
If the PLL is enabled and both the multiplication and division factors
equal one, then CLKOUT is also synchronized to EXTAL.
If the PLL is disabled, the CLKOUT frequency is half the frequency of
EXTAL.
PINIT/NMI
Input
Input
PLL Initial/Non-Maskable Interrupt—During assertion of RESET,
the value of PINIT/NMI is written into the PLL Enable (PEN) bit of the
PLL control register, determining whether the PLL is enabled or
disabled. After RESET deassertion and during normal instruction
processing, the PINIT/NMI Schmitt-trigger input is a
negative-edge-triggered Non-Maskable Interrupt (NMI) request
internally synchronized to CLKOUT.
PINIT/NMI can tolerate 5 V.
Summary of Contents for DSP56303
Page 1: ...DSP56303 User s Manual 24 Bit Digital Signal Processor DSP56303UM AD Revision 1 January 2001 ...
Page 52: ...JTAG OnCE Interface 2 22 DSP56303 User s Manual ...
Page 114: ...General Purpose Input Output GPIO 5 10 DSP56303 User s Manual ...
Page 212: ...GPIO Signals and Registers 8 26 DSP56303 User s Manual ...
Page 268: ...Interrupt Equates A 22 DSP56303 User s Manual ...
Page 306: ...Programming Sheets B 38 DSP56303 User s Manual ...
Page 320: ...Index 14 DSP56303 User s Manual ...