Motorola DSP56012 - Manual (Page 49)

Signal Descriptions
Interrupt and Mode Control
MOTOROLA DSP56012 User’s Manual 2-9
MODC/NMI Input Input Mode Select C/Non-maskable Interrupt Request — This
input has two functions:
1. to select the initial chip operating mode, and
2. after internal synchronization, to allow an
external device to request a non-maskable DSP
interrupt.
MODC is read and internally latched in the DSP when the
processor exits the Reset state. MODA, MODB, and
MODC select the initial chip operating mode. Several
clock cycles (depending on PLL stabilization time) after
leaving the Reset state, the MODC signal changes to the
nonmaskable external interrupt request NMI. After reset,
the chip operating mode can be changed by software. The
NMI input is an external interrupt request that indicates
that an external device is requesting service. It may be
programmed to be level-sensitive or
negative-edge-sensitive.
RESET Input Input Reset— This input is a direct hardware reset on the
processor. When RESET is asserted low, the DSP is
initialized and placed in the Reset state. A Schmitt trigger
input is used for noise immunity. When the RESET signal
is deasserted, the initial chip operating mode is latched
from the MODA, MODB, and MODC signals. The
internal reset signal is deasserted synchronous with the
internal clocks. In addition, the PINIT pin is sampled and
written into the PEN bit of the PLL Control Register.
Table 2-5 Interrupt and Mode Control (Continued)
Signal Name Type
State During
Reset
Signal Description