Motorola DSP96002 User Manual page 20

An implementation of a bus arbitration scheme may hold
owner if none of the other devices are requesting the bus. As a consequence, the current bus master may
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keep B A asserted after ceasing bus activity, regardless of whether
This situation is called "bus parking" and allows the current bus master to use the bus repeatedly without
re-arbitration until some other device requests the bus.
DSP96002
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B
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B
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B
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B
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B L
5.16.2 Bus Handshake Unit
The bus handshake unit in the DSP96002 is implemented within a finite state machine. It consists of two
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external outputs ( B
(ext_acc_req, end_of_sequence, RH) (see Figure 2-8). The ext_acc_req signal is asserted when one or
more requests for external bus access are pending, and remains asserted as long as the transfers are
being executed. The end_of_sequence signal is asserted at the last bus cycle of the current sequence.
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B
ext_acc_req
end_of_sequence
Request Hold (RH)
MOTOROLA
ARBITRATION
LOGIC
Figure 2-7. Bus Arbitration Scheme
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R, B A), two external
HANDSHAKE
Figure 2-8. Bus Handshake Unit
DSP96002 USER'S MANUAL
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B G asserted, for example, to the current bus
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B
V
cc
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inputs ( B G, B
BUS
UNIT
–
R is asserted or deasserted.
DSP96002
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B
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B
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B
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B
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B L
B) and three internal inputs
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B B
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B R
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B A
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