US 8,527,682 B2Granted

Bus controller, bus communication system, and bus control method

AssigneeMitsubishi Electric Corporation

InventorsHiroshi Ootaki, Yasuhito Oomiya

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Abstract

It is an object to prevent a command-issuing interval from being fixed and then avoid a situation where a target always returns a retry by varying a timing of a command-issuing request (i.e., a request signal) from each initiator, even if a plurality of initiators simultaneously or alternately make a plurality of command-issuing requests (i.e., send request signals). Based on predetermined priorities, a bus control unit sends a grant signal to an initiator that has sent a request signal, thereby granting use of a bus to the initiator. A mask generating unit sends a mask signal to at least one initiator to have the initiator mask a request signal, thereby controlling a timing, at which the bus control unit grants use of the bus to the initiator, to be aperiodic.

Claims9

Dependent claims

A bus controller for controlling a bus communication system wherein each initiator of a plurality of initiators connected to a bus generates and sends a request signal to request use of the bus at predetermined intervals, and upon being granted use of the bus in response to the request signal, sends a command signal to instruct execution of a predetermined process to a target connected to the bus, and when the each initiator determines that the predetermined process is not to be executed by the target, the each initiator sends, upon being granted use of the bus again, the command signal to the target, the bus controller comprising:

a bus control unit configured to, upon receiving the request signal from the each initiator, grant use of the bus to the each initiator based on predetermined priorities;
and
a mask generating unit configured to mask the request signal generated by the each initiator to control a timing, at which the request signal is sent from the each initiator, to be aperiodic,
wherein the mask generating unit includes
a mask interval setting unit configured to set, as a mask interval, an interval for masking the request signal generated by the each initiator;
a mask condition setting unit configured to set, as a plurality of mask conditions, a plurality of combinations of initiators to be subject to masking, the plurality of mask conditions including as many excluding mask conditions as the plurality of initiators, each of the excluding mask conditions corresponding to each of the plurality of initiators and being a combination of initiators to be subject to masking from which only the each of the plurality of initiators corresponding to the each of the excluding mask conditions is excluded among the plurality of initiators;
and
a counter of an initiator mask ID (identifier) corresponding to each of the plurality of mask conditions set by the mask condition setting unit, and
wherein the mask generating unit, at each mask interval set by the mask interval setting unit, counts up the counter, determines a selected initiator to be subject to masking among the plurality of initiators, the selected initiator having the initiator mask ID indicated by the counter, and masks a request signal generated by the selected initiator.

6 more elements

A bus communication system comprising a plurality of initiators and at least one target both connected to a bus,

wherein each initiator generates and sends a request signal to request use of the bus at predetermined intervals, and upon being granted use of the bus in response to the request signal, sends a command signal to instruct execution of a predetermined process to a target, and when the each initiator determines that the predetermined process is not to be executed by the target, the each initiator sends, upon being granted use of the bus again, the command signal to the target,
the bus communication system further comprising a bus controller connected to the bus, the bus controller including a bus control unit configured to, upon receiving the request signal from the each initiator, grant use of the bus to the each initiator based on predetermined priorities, and a mask generating unit configured to mask the request signal generated by the each initiator to control a timing, at which the request signal is sent from the each initiator, to be aperiodic,
wherein the mask generating unit includes
a mask interval setting unit configured to set, as a mask interval, an interval for masking the request signal generated by the each initiator;
a mask condition setting unit configured to set, as a plurality of mask conditions, a plurality of combinations of initiators to be subject to masking, the plurality of mask conditions including as many excluding mask conditions as the plurality of initiators, each of the excluding mask conditions corresponding to each of the plurality of initiators and being a combination of initiators to be subject to masking from which only the each of the plurality of initiators corresponding to the each of the excluding mask conditions is excluded among the plurality of initiators;
and
a counter of an initiator mask ID (identifier) corresponding to each of the plurality of mask conditions set by the mask condition setting unit, and
wherein the mask generating unit, at each mask interval set by the mask interval setting unit, counts up the counter, determines a selected initiator to be subject to masking among the plurality of initiators, the selected initiator having the initiator mask ID indicated by the counter, and masks a request signal generated by the selected initiator.

5 more elements

A bus control method for controlling a bus communication system wherein each initiator of a plurality of initiators connected to a bus generates and sends a request signal to request use of the bus at predetermined intervals, and upon being granted use of the bus in response to the request signal, sends a command signal to instruct execution of a predetermined process to a target connected to the bus, and when the each initiator determines that the predetermined process is not to be executed by the target, the each initiator sends, upon being granted use of the bus again, the command signal to the target, the bus control method comprising:

granting use of the bus to the each initiator based on predetermined priorities upon receiving the request signal from the each initiator;
and
masking the request signal generated by the each initiator to control a timing, at which the request signal is sent from the each initiator, to be aperiodic,
wherein the masking includes
setting, as a mask interval, an interval for masking the request signal generated by the each initiator;
setting, as a plurality of mask conditions, a plurality of combinations of initiators to be subject to masking, the plurality of mask conditions including as many excluding mask conditions as the plurality of initiators, each of the excluding mask conditions corresponding to each of the plurality of initiators and being a combination of initiators to be subject to masking from which only the each of the plurality of initiators corresponding to the each of the excluding mask conditions is excluded among the plurality of initiators;
and
at each of the mask interval, counting up a counter of an initiator mask ID (identifier) corresponding to each of the plurality of mask conditions, determining a selected initiator to be subject to masking among the plurality of initiators, the selected initiator having the initiator mask ID indicated by the counter, and masking a request signal generated by the selected initiator.

5 more elements

Dependencies are inferred from the claim text.