摘要:
In a data processing system having a first bus sized to accomodate 2.sup.x units of data and a second bus sized to accomodate 2.sup.y units of data, where x and y are positive integers and y is less than or equal to x, a method and apparatus for determining y from the x least significant bits of a control address, concatenated with a decode control bit, and then decoding the (x-y) most significant bits of the x control address bits to determine which of x data unit transceivers coupled between the first and second buses should be enabled.
摘要:
A method and apparatus for reducing power consumption in a data processing system by interrupting the supply of clocking pulses to selected portions of the system in response to a power-down signal provided by a data processing portion of the system only if the state of a respective control signal indicates that that particular portion of the system is then disabled or otherwise inhibited from interrupting the operation of the data processing portion.
摘要:
A method and system for transmitting binary-coded data use partitioning of data words in a plurality of data nibbles. The data nibbles are coded using modified a 1-bit hot coding format that transforms a data nibble in a data segment including a plurality of bit groups. A change in a digital state at a bit position in a more significant bit group is maintained at that bit position in less significant bit groups, and information is transmitted in a form of a transition between digital states. The data segments are transmitted in phases each including one bit group from each data segment. At a receiving terminal, the bit groups are converted back in the binary-coded data words. In one application, the invention is used to reduce power consumption during data transmissions to and from an integrated circuit device.
摘要:
A method and apparatus for providing both power and control by way of an integrated circuit terminal (22). In one form, a clock source (12) supplies a periodic signal to a phase lock loop circuit (32) and to a multiplexer (34). The output of the phase lock loop circuit (32) is a second input to the multiplexer (34). The phase lock loop circuit (32) receives its power from a power and control pin (22). The multiplexer (34) receives its power from a power pin (24). The power and control pin (22) is used as a control input to multiplexer (34). Multiplexer (34) uses the power and control pin (22) to select which input to output as a system clock.
摘要:
A data processing system (10) and method is used to recover a CPU from faulty operation. A single timer (38) is used to enable recovery operations. When the timer (38) experiences a first time-out event, a software watchdog interrupt (28) is generated. If the software interrupt (28) is properly handled before another consecutive/subsequent watchdog time out occurs, normal software execution will resume. However, if the software watchdog interrupt is not processed and the watchdog timer (38) experiences a second time-out event while the watchdog time-out interrupt (28) is pending, the timer (38) will generate a bus transfer termination signal (30) and set a status bit (270) within a watchdog status register (44). This assertion of termination signal (30) and the setting of the bit (270) allows the microprocessor to determine that a locked bus state exists. In response to the signal (30) and the bit (270), the locked bus (one or more of busses 22, 24, and/or 26) will attempt to recover from the locked bus state.
摘要:
A synchronous memory interface feeds back a buffered (34) clock signal to a microcontroller (20) to simplify and improve output hold time for the memory (38). An output delay circuit (36) in the microcontroller (20) is controlled by the same delayed clock signal as the synchronous memory (38). This delay circuit (36) selectively delays memory signals to the synchronous memory (38) from the microcontroller delay circuit (36). The use of flip-flops (40, 44) in the delay circuit (36) provides a mechanism for scan testing. This enables three different selectable modes of operation of the delay circuit (36) providing flexibility in interfacing in different environments.
摘要:
A bus interface unit within a processor ensures a delay period after the occurrence of a read operation to avoid bus contention on a multiplexed bus, When there is a requirement for a back-to-back read or write operation subsequent to the read bus cycle on a multiplexed bus it is important to allow devices, such as memory, sufficient time to reset after transmission of data. To avoid the bus contention problem that occurs after a read bus cycle, i.e, prevent a next address on the bus until the bus is in a tri-state condition, one embodiment inserts idle clock cycles subsequent to a read but not subsequent to a write, The present invention avoids bus contention on a multiplexed bus while providing flexibility in interfacing with a variety of memory devices, and providing a flexible processor design.
摘要:
Circuitry is implemented within an integrated circuit ("chip") (101) which is an IEEE 1149.1 compliant device capable of performing JTAG testing (104), such as an EXTEST or CLAMP testing procedure. Upon exiting of either of these procedures, the input/output pins (210) of the chip are placed in a known state, which may be a high impedance state.
摘要:
A data processing system (10) having a bus controller (5) that uses a communication bus (22) which adapts to various system resources (7) and is capable of burst transfers. In one embodiment, the processor core (2) and system resources (7) supply control signals supplying required parameters of the next transfer. The bus controller is capable of transferring operands and/or instructions in incremental bursts from these system resources. Each transfer data burst has an associated unique access address where successive bytes of data are associated with sequential addresses and the burst increment equals the data port size. The burst capability is dependent on the ability of system resource (7) to burst data and can be inhibited with a transfer burst inhibit signal. The length of the desired data is controlled by a sizing signal from the core (2) or from cache and the increment size is supplied by the resource (7).
摘要:
A programmable clock generator (220), which is part of an integrated circuit (IC) (210), provides clock signals (230) and (232) to various components of the IC. The clock generator includes a PLL (322) and one or more choppers (326, 328) which provide a desired waveform to the IC for testing purposes. When used in conjunction with a tester (212, 312), the IC can be scan tested at-speed using slower and less expensive testing equipment.