Motorola DSP56012 - Manual (Page 48)

2-8 DSP56012 User’s Manual MOTOROLA
Signal Descriptions
Interrupt and Mode Control
2.5 INTERRUPT AND MODE CONTROL
Table 2-5 Interrupt and Mode Control
Signal Name Type
State During
Reset
Signal Description
MODA/IRQA Input Input Mode Select A/External Interrupt Request A— This
input has two functions:
1. to select the initial chip operating mode, and
2. after synchronization, to allow an external device
to request a DSP interrupt.
MODA 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 MODA signal changes to
external interrupt request IRQA. The chip operating
mode can be changed by software after reset. The IRQA
input is a synchronized external interrupt request that
indicates that an external device is requesting service. It
may be programmed to be level-sensitive or
negative-edge-sensitive. If the processor is in the Stop
state and IRQA is asserted, the processor will exit the Stop
state.
MODB/IRQB Input Input Mode Select B/External Interrupt Request B —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 DSP interrupt.
MODB 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 MODB signal changes to
external interrupt request IRQB. After reset, the chip
operating mode can be changed by software. The IRQB
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-triggered.