Microchip Technology Inc.

Vlsi Technology, Inc.

Rodney J Pesavento

Joseph W Triece

Gregg Lahti

James C Steele

Philip Wszolek

Brian N Fall

David K Cassetti

Swaroop Adusumilli

Steven Dawson

Barry M Davis

Nick Richardson

Igor Wojewoda

D C Sessions

Roshan Samuel

Gregg D Lahti

Sergey Pavlov

James Casady

A system has at least one bus, a central processing unit (CPU) coupled with the bus, a memory coupled with the bus, a direct memory access (DMA) controller having a plurality of DMA channels and operating independently from the CPU and being coupled with the bus, wherein for access to the bus the DMA controller is programmable in a first mode to have priority over the CPU and in a second mode in which at least one DMA channel of the DMA controller is suspended from accessing the bus.

Direct memory access controller

A serial peripheral interface is configurable to operate in a IS transmission mode. The interface has a transmission unit connected with external pins for data, bit clock, and left/right clock signal, a first-in-first-out (FIFO) buffer with a plurality of memory lines, and a control unit operable to read data portions from two memory lines, to assemble them into a transmission word, and to forward the assembled transmission word to the transmission unit, wherein the transmission unit is configured to serially transmit the assembled transmission word through the external data pin.

[object Object]

A multi-boot device capable of booting from a plurality of boot devices, each storing a boot image. The multi-boot device determines which boot device to load based on sequence numbers assigned to each of the boot devices. Some embodiments will make this determination using only hardware operations. The multi-boot device compares the sequence numbers of the available boot devices in order to determine the boot image to be loaded. The address of the selected boot image is then mapped to the device's default boot vector. The remaining images are likewise mapped to a secondary boot memory. The device then boots from the default boot vector. The user can change the boot device to be loaded by modifying one or more of the boot sequence numbers. The boot images can be updated without resetting the device by switching execution to and from boot images in the secondary boot memory.

Boot sequencing for multi boot devices

A cache module for a central processing unit has a cache control unit with an interface for a memory, a cache memory coupled with the control unit, wherein the cache memory has a plurality of cache lines, at least one cache line of the plurality of cache lines has an address tag bit field and an associated storage area for storing instructions or data, wherein the address tag bit field is readable and writeable and wherein the cache control unit is operable upon detecting that an address has been written to the address tag bit field to initiate a preload function in which instructions or data from the memory are loaded from the address into the at least one cache line.

Configurable cache for a microprocessor

A microcontroller or integrated system has a bus, a plurality of peripheral devices each one coupled with the bus, a non-volatile memory, and a state machine coupled with the non-volatile memory and being operable to initialize the peripheral devices by reading initialization information from the non-volatile memory and writing it to the peripheral devices.

Dynamic state configuration restore

A system has a central processing unit (CPU) operable to operate in a sleep or low power mode and in an active mode, a plurality of system components operable to operate in a sleep or low power mode and in an active mode, and a direct memory access (DMA) controller operating independently from the CPU and operable to operate in a sleep or low power mode and in an active mode, wherein the DMA controller is further operable to transfer data from and to a memory or peripheral device, wherein when the system is in a sleep or low power mode, only the DMA controller and any system component which is necessary to perform a DMA transaction are switched into active mode.

A cache module for a central processing unit has a cache control unit coupled with a memory, and a cache memory coupled with the control unit and the memory wherein the cache memory has a plurality of cache lines, each cache line having a storage area for storing instructions to be issued sequentially and associated control bits, wherein at least one cache line of the plurality of cache lines has at least one branch trail control bit which when set provides for an automatic locking function of the cache line in case a predefined branch instruction has been issued.

A cache module for a central processing unit has a cache control unit coupled with a memory, and a cache memory coupled with the control unit and the memory, wherein the cache memory has a plurality of cache lines, at least one cache line of the plurality of cache lines has an address tag bit field and an associated storage area for storing instructions to be issued sequentially and at least one control bit field, wherein the control bit field is coupled with the address tag bit field to mask a predefined number of bits in the address tag bit field.

An interrupt controller has an interrupt register unit receiving a plurality of interrupt source signals, an interrupt detector coupled to the interrupt register unit, a counter unit coupled to the interrupt detector, wherein on the first occurrence of an interrupt source signal the counter unit defines a time window during which the interrupt register stores further interrupt source signals, and an interrupt request unit coupled to the counter unit for generating an interrupt request signal.

Interrupt controller handling interrupts with and without coalescing

A computer system in which a host bus is relieved from the burdens of data transfers between main memory and devices connected to an input/output (I/O) bus. Instead, the invention operates to place most of the burden of the data transfer on an internal bus within a bus arbitration unit so that the host bus is freed up much sooner than conventionally achieved. As a result, the computer system has substantially better performance because the host bus is available for other processing operations instead of being tied up with data transfers with devices (e.g., peripheral devices) connected to the I/O bus.

Method and apparatus for direct access to main memory by an I/O bus

A computer system in which a host bus is relieved from the burdens of data transfers between main memory and devices connected to an input/output (I/O) bus (e.g., peripheral devices). Instead, the invention operates to place most of the burden of the data transfer on an internal bus within a bus arbitration unit so that the host bus is freed up much sooner than conventionally achieved. Further, to reduce stalling of a processor seeking access to the main memory via the host bus and the internal bus, the host bus is able to gain access to the main memory using the internal bus during times in which the internal bus is temporarily not needed by the data transfer between the main memory and the peripheral devices. As a result, the computer system has substantially better performance because the host bus is available for other processing operations instead of being tied up with data transfers with peripheral devices, and because the internal bus is occasionally freed up during the data transfer between the main memory and the peripheral devices.

Method and apparatus for arbitrating access to main memory of a computer

A link system controller is interposed between a PCI bus and the data bus and memory data bus of a personal computer system to normally allow transfer of write information from the PCI bus to DRAM memories on the memory data bus. Whenever a request is made for the transfer of data to the CPU data bus, a CPU bus interface controller requests release of the system from the DRAM controller. The DRAM controller then grants permission or releases control to the CPU bus interface whenever the DRAM controller is not writing data out to the DRAM data bus. When this release is effected, the transfer of write data to the memory data bus is prevented and transfer of data to the CPU data bus is enabled. This prevents simultaneous switching of the devices on both the CPU data bus and the memory data bus, to reduce the generation of noise; so that the operation of the IC system device is not impaired.

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Chandler, AZ, United States of America

Rodney J Pesavento