Bus system design method, bus system, and device unit
AssigneeFujitsu Limited
InventorRyohei Nishimiya
Life of this patent
Estimating the term…
Abstract
On the basis of a period of a timing signal, a signal propagation delay in a device unit, signal propagation delay in the timing signal bus and the data bus, and a setup time of another device unit or a device connected to the data bus, a timing at which noise caused by active connection of the first device to the data bus is propagated to the other device unit or the device is computed in a step of noise propagation computing, and on the basis of the timing computed in the step of noise propagation computing, a connection timing at which the first device unit is connected to the data bus. With thes two steps, a noise caused by active connection of a device unit does not affect other device units and devices connected to the same data bus.
Claims14
A design method for a bus system equipped with a plurality of device units, a data bus to which the plural device units are connectable, a timing-signal supply source for supplying a timing signal to said plural device units through a timing-signal bus, a bus switch for connecting and disconnecting a signal between said plural device units and said data bus, and a bus switch controller for controlling connecting and disconnecting operations performed by said bus switch, comprising the steps of:
- for each of said plural device units,
- computing noise propagation timing at which, when each said device unit is connected to said data bus being active, a noise propagates to other one of said plural device units or another device connected to said data bus based on a period of said timing signal, a signal propagation delay in each said device unit, signal propagation delays in said timing-signal bus and said data bus, and a setup time in the other device unit or in the device connected to said data bus;
- and
- computing, based on said noise propagation timing computed in said step of noise propagation computing, connection timing at which each said device unit is to be connected to said data bus.
A bus system comprising:
- a plurality of device units;
- a data bus to which the plural device units are connectable;
- a timing-signal supply source for supplying a timing signal to said plural device units through a timing-signal bus;
- a bus switch for connecting and disconnecting a signal between said plural device units and said data bus;
- and
- a bus switch controller for controlling the connecting and disconnecting operations of said bus switch by issuing, to said bus switch, a connection control signal for connecting each of said plural device unit and said data bus;
- wherein
- said bus switch controller controls said bus switch so that each said device unit is connected to said data bus after a control delay time “b” between receipt of said timing signal and issue of said connection control signal to said bus switch in said bus switch controller after each said device unit is connected to said timing-signal bus;
- and
- on the basis of the period “T” of said timing signal, skew “a” from said timing-signal supply source to said bus switch controller, the control delay time “b”, a signal propagation delay time “c” between said bus switch controller and said bus switch, an operating delay time “d” of said bus switch, a pulse width (time) “e” of a noise caused when each said device unit is connected to said data bus being active, a propagation delay time “f” of said noise in each said device unit and said data bus, skew “g” from said timing-signal supply source to other one of said plural device units or a device connected to said data bus, and a setup time “S” in said bus system, the control delay time “b” is computed as a value such that a timing margin M{=(T+g)−(a+b+c+d+e+f)−S} from arrival of said noise at the other device unit or the device to start of said setup time is 0 or greater.
A device unit installable to a bus unit equipped with a data bus, a timing-signal supply source, and a timing-signal bus connected to said timing-signal supply source, comprising:
- a bus switch for connecting and disconnecting a signal between said device unit and said data bus;
- and
- a bus switch controller for controlling connecting and disconnecting operations of said bus switch by issuing, to said bus switch, a connection control signal for connecting said device unit and said data bus;
- wherein
- said bus switch controller controls said bus switch so that said device unit is connected to said data bus after a control delay time “b” between receipt of said timing signal and issuing of the connection control signal to said bus switch in the bus switch controller after said device unit is connected to said timing-signal bus;
- and on the basis of a period “T” of said timing signal, skew “a” from said timing-signal supply source to said bus switch controller, the control delay time “b”, a signal propagation delay time “c” between said bus switch controller and said bus switch, an operating delay time “d” of said bus switch, a pulse width (time) “e” of a noise caused when said device unit is connected to said data bus being active, a propagation delay time “f” of said noise in said device unit and said data bus, skew g from said timing-signal supply source to another device unit other than said first device unit or a device connected to said data bus, and a setup time “S” in said bus system, the control delay time “b” of said bus switch is computed as a value such that a timing margin M{=(T+g)−(a+b+c+d+e+f)−S} from arrival of said noise at the second device unit or the device to start of said setup time is 0 or greater.
A device unit installable to a bus unit equipped with a data bus, a timing-signal supply source, and a timing-signal bus connected to said timing-signal supply source, comprising:
- a bus switch for connecting and disconnecting a signal between said device unit and said data bus;
- and
- a bus switch controller, including an adjustment circuit for changing a phase of a timing signal supplied by said timing signal supply source through said timing-signal bus, for controlling connecting and disconnecting operations of said bus switch by issuing, to said bus switch, a connection control signal for connecting said device unit and said data bus based on the timing signal whose phase has been changed.
Dependencies are inferred from the claim text.