Motorola DSP56012 3.8 OPERATION ON HARDWARE RESET

3-20 DSP56012 User’s Manual MOTOROLA
Memory, Operating Modes, and Interrupts
Operation on Hardware Reset
3.8 OPERATION ON HARDWARE RESET
The processor enters the Reset processing state when the external RESET pin is
asserted (hardware reset occurs). The Reset state:
• resets internal peripheral devices and initializes their control registers as
described in the peripheral sections,
• sets the modifier registers to $FFFF,
• clears the Interrupt Priority Register,
• clears the Stack Pointer,
• clears the Scaling mode, Trace mode, Loop Flag, Double Precision Multiply
mode and condition code bits, and sets the interrupt mask bits of the Status
Register (SR), and
• clears the Stop Delay (SD) bit and the Program RAM Enable (PEA and PEB)
bits in the OMR.
The DSP remains in the Reset state until the RESET pin is deasserted. When the
processor leaves the Reset state it:
• loads the chip operating mode bits of the OMR from the external mode select
pins (MODC, MODB, MODA), and
• begins program execution of the bootstrap ROM starting at address $0000.
Figure 3-7 PLL Configuration
Divider Out
EXTAL
VCO Out
MF[11:0]
DF[3:0]
Phase
Detector
(PD)
Charge
Pump
Loop
Filter
Voltage
Controlled
Oscillator
(VCO)
Low
Power
Divider
20 to 215
Multiplication
Factor
1 to 4096
Frequency
Multiplier
AA0293k