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Signal/Connection Descriptions
Host Interface (HI08)
Table 2-9 Interrupt and Mode Control (Continued)
Signal Name
MODD
Input
IRQD
2.8
HOST INTERFACE (HI08)
The HI08 provides a fast parallel 8-bit port, which can connect directly to the host bus.
The HI08 supports a variety of standard buses and can be directly connected to a
number of industry standard microcomputers, microprocessors, DSPs, and DMA
hardware.
2.8.1
Host Port Usage Considerations
When reading multiple-bit registers that are written by another asynchronous system,
you must synchronize carefully. This problem commonly occurs when two
asynchronous systems are connected (as they are in the host port). The considerations
for proper operation are discussed in Table 2-10.
2-16
State
Type
During
Reset
Input
Mode Select DÑMODD is an active-low
Schmitt-trigger input, internally synchronized to
CLKOUT. MODA, MODB, MODC, and MODD
select one of 16 initial chip operating modes,
latched into OMR when the RESET signal is
deasserted.
External Interrupt Request DÑAfter hardware
reset, this signal becomes a level-sensitive or
negative-edge-triggered, maskable interrupt
request input during normal instruction
processing. If IRQD is asserted synchronous to
CLKOUT, multiple processors can be
resynchronized using the WAIT instruction and
asserting IRQD to exit the wait state.
DSP56309UM/D
Signal Description
MOTOROLA
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