SIGNAL DESCRIPTIONS
MOTOROLA
DSP56002 PIN DESCRIPTIONS
2 - 7
time of the interrupt signal increases, the probability that noise on IRQA will generate mul-
tiple interrupts also increases.
2.2.3.2
Mode Select B/External Interrupt Request B (MODB/IRQB)
This input pin works with the MODA and MODC pins to select the chip’s operating mode,
and it receives an interrupt request from an external source. Reset causes this input to act
as MODB.
During reset, this pin should be forced to the desired state, because as the chip comes
out of reset, it reads the states of the mode pins and writes the information to the Operat-
ing Mode Register, which sets the chip’s operating mode. After the chip has left the reset
state, the MODB pin automatically changes to external interrupt request IRQB.
IRQB receives external interrupt requests. It can be programmed to be level sensitive or
negative edge triggered. When the signal is edge triggered, triggering occurs at a voltage
level and is not directly related to the fall time of the interrupt signal. However, as the fall
time of the interrupt signal increases, the probability that noise on IRQB will generate mul-
tiple interrupts also increases.
2.2.3.3
Mode Select C/Non-Maskable Interrupt Request (MODC/NMI)
This input pin works with the MODA and MODB pins to select the chip’s operating mode,
and it receives an interrupt request from an external source. Reset causes this input to act
as MODC.
During reset, this pin should be forced to the desired state, because as the chip comes out
of reset, it reads the states of the mode pins and writes the information to the Operating
Mode Register, which sets the chip’s operating mode. After the chip has left the reset state,
the MODC pin automatically changes to a nonmaskable interrupt request (NMI) input.
The negative-edge triggered NMI receives nonmaskable interrupt requests. Triggering
occurs at a voltage level and is not directly related to the fall time of the interrupt signal.
However, as the fall time of the interrupt signal increases, the probability that noise on NMI
will generate multiple interrupts also increases.
2.2.3.4
Reset (RESET)
This Schmitt trigger input pin is used to reset the DSP56002. When RESET is asserted,
the DSP56002 is initialized and placed in the reset state. When RESET is deasserted,
the chip writes the mode pin (MODA, MODB, MODC) information to the operating mode
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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