Modular chip select control circuit and method for performing pipelined memory accesses
First Claim
1. A modular chip select control circuit, comprising:
- an address decode stage having a first plurality of address decoders, each address decoder associated with a programmable region and activating at least one corresponding control signal if an input address is within said programmable region;
a timing control stage coupled to said address decode stage, having a second plurality of control units, each control unit receiving said at least one corresponding control signal from each of said first plurality of address decoders and responsive thereto to provide a corresponding plurality of timing signals to control a memory access; and
a pin configuration stage coupled to said address decode stage and to said timing control stage, having a third plurality of pin configuration logic circuits, each pin configuration logic circuit programmable to provide a selected one of a plurality of chip select signals and responsive to selected ones of said corresponding plurality of timing signals of each of said second plurality of control units to provide said selected one of said plurality of chip select signals.
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Accused Products
Abstract
A modular chip select control circuit (80) is scalable by having an address decode stage (90) with a first number of address decoders, a control stage (100) with a second number of control units, and a pin configuration stage (110) with a third number of pin configuration logic circuits. These three numbers, defining the number of memory regions, the access pipeline depth, and the number of chip select signals, respectively, are independent and may be changed between chip designs to accommodate different system needs. The control stage includes an early pipeline control circuit (186) which allows the control units (170, 180) to pipeline pending memory cycles, based on an accessed region'"'"'s characteristics. The early pipeline control circuit (186) together with the control units (170, 180) enforce a set of pipelining rules to ensure data integrity and proper cycle termination, thus providing an efficient series of pipelined memory access cycles.
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Citations
28 Claims
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1. A modular chip select control circuit, comprising:
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an address decode stage having a first plurality of address decoders, each address decoder associated with a programmable region and activating at least one corresponding control signal if an input address is within said programmable region; a timing control stage coupled to said address decode stage, having a second plurality of control units, each control unit receiving said at least one corresponding control signal from each of said first plurality of address decoders and responsive thereto to provide a corresponding plurality of timing signals to control a memory access; and a pin configuration stage coupled to said address decode stage and to said timing control stage, having a third plurality of pin configuration logic circuits, each pin configuration logic circuit programmable to provide a selected one of a plurality of chip select signals and responsive to selected ones of said corresponding plurality of timing signals of each of said second plurality of control units to provide said selected one of said plurality of chip select signals. - View Dependent Claims (2, 3, 4)
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5. A method for performing pipelined memory accesses, comprising the steps of:
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receiving and storing a first plurality of bits for controlling accesses to a first programmable region via a bus; receiving and storing a second plurality of bits for controlling accesses to a second programmable region via said bus; detecting a first access to said first programmable region using a portion of said first plurality of bits; detecting a second access to said second programmable region using a portion of said second plurality of bits prior to a completion of said first access, said second access characterized as being a read access; performing an address phase of said first access by providing a first chip select signal; performing a data phase of said first access by providing a second chip select signal; performing an address phase of said second access during at least a portion of said data phase of said first access by providing a third chip select signal; and performing a data phase of said second access by providing a fourth chip select signal. - View Dependent Claims (6, 7, 8, 9, 10, 11)
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12. A method for performing pipelined memory accesses, comprising the steps of:
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receiving and storing a first plurality of bits for controlling accesses to a first programmable region via a bus; receiving and storing a second plurality of bits for controlling accesses to a second programmable region via said bus; detecting a first write access to said first programmable region using a portion of said first plurality of bits; detecting a second write access to said second programmable region using a portion of said second plurality of bits prior to a completion of said first write access; performing an address phase of said first write access by providing a first chip select signal; performing a data phase of said first write access by providing a second chip select signal; performing an address phase of said second write access during at least a portion of said data phase of said first write access by providing a third chip select signal; and performing a data phase of said second write access by providing a fourth chip select signal. - View Dependent Claims (13, 14, 15, 16)
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17. A method for performing pipelined memory accesses, comprising the steps of:
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receiving and storing a first plurality of bits for controlling accesses to a first programmable region via a bus; receiving and storing a second plurality of bits for controlling accesses to a second programmable region Via said bus; detecting a first access to said first programmable region using a portion of said first plurality of bits, said first access characterized as being a read access; detecting a second access to said second programmable region using a portion of said second plurality of bits prior to a completion of said first access, said second access characterized as being a write access; performing an address phase of said first access by providing a first chip select signal; performing a data phase of said first access by providing a second chip select signal; performing a first portion of an address phase of said second access by providing an address of said address phase of said second access during at least a portion of said data phase of said first access; performing a second portion of said address phase of said second access after a completion of said data phase of said first access by providing a third chip select signal; and performing a data phase of said second access by providing a fourth chip select signal. - View Dependent Claims (18, 19, 20)
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21. A method for performing pipelined memory accesses, comprising the steps of:
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receiving and storing a first plurality of bits for controlling accesses to a first programmable region via a bus; receiving and storing a second plurality of bits for controlling accesses to a second programmable region via said bus; detecting a first access to said first programmable region using a portion of said first plurality of bits; detecting a second access to said second programmable region using a portion of said second plurality of bits prior to a completion of said first access; performing an address phase of said first access by providing a first chip select signal; performing a data phase of said first access by providing a second chip select signal; performing an address phase of said second access by providing a third chip select signal, during at least a portion of said data phase of said first access if, said first and second pluralities of bits indicate that at least one of said first and second programmable regions, respectively, provides a transfer acknowledge input signal to control a termination of a corresponding data phase, and said second plurality of bits indicates that said second programmable region can hold off a data output thereof; and performing a data phase of said second access by providing a fourth chip select signal. - View Dependent Claims (22, 23, 24)
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25. A method for performing pipelined memory accesses, comprising the steps of:
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receiving and storing a first plurality of bits for controlling accesses to a first programmable region via a bus; receiving and storing a second plurality of bits for controlling accesses to a second programmable region via said bus; detecting a first read access to said first programmable region using a portion of said first plurality of bits; detecting a second read access to said second programmable region using a portion of said second plurality of bits prior to a completion of said first read access; performing an address phase of said first read access by providing a first chip select signal; performing a data phase of said first read access by providing a second chip select signal; performing an address phase of said second read access by providing a third chip select signal, during at least a portion of said data phase of said first read access if, said first plurality of bits indicates that said first programmable region is a burstable region, and said second plurality of bits indicates that said second programmable region is a burstable region which can hold off a data output thereof; and performing a data phase of said second read access by providing a fourth chip select signal. - View Dependent Claims (26, 27, 28)
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Specification