Abstract: In an embodiment, the invention provides a method for characterizing a threshold voltage of a flash memory cell. The method comprises generating a pulse train signal on flash memory IC, applying the pulse train signal to an external low-pass filter, and applying an output of the low-pass filter to the input of an external gain stage. An analog signal from the output of the gain stage is directed to a control gate of the flash memory cell. An electrical parameter of the flash memory cell is measured by an external tester.

Abstract: In an embodiment, the invention provides a method for correcting soft errors in memory. A block of data is written in memory wherein all rows and all columns have a first checksum appended to it. A second checksum for each row and each column is generated after reading each row and each column from memory. The first and second checksum for each row and each column are compared for a compare such that when one and only one column has a miscompare, the logical value of any bit at an intersection of the one and only one column that has a miscompare and any row that has a miscompare is reversed.

Abstract: In a data processing system in which the complete set of op-code signal groups are stored in a ROM unit, a programmable, non-volatile memory unit stores the address signal groups of the set of op-code signal groups currently controlling the operation of the data processing system. In addition, the programmable, non-volatile memory unit has error checking and correction signal groups associated with each op-code signal groups. To retrieve an op-code signal group from the ROM unit, the central processing unit applies a pointer/address signal group to the programmable, non-volatile memory. The op-code address and the error checking and correction signal group at the location specified by the pointer/address signal group is retrieved from the programmable, non-volatile memory unit, subjected to error checking and correction procedures and the resulting address signal groups is applied to the ROM unit.

Abstract: A digital signal processing system includes multiple processor subsystems, an external input/output port (XPORT), and an XPORT arbiter. The processor subsystems each include a processor core and a DMA controller. The XPORT arbiter arbitrates between the processor cores and between the DMA controllers, and further arbitrates between processor control or DMA control of the XPORT. Upon a request signal from a DMA controller, the XPORT arbiter asserts a hold signal to the processor cores. The processor cores respond by asserting a hold acknowledge signal. A processor core will delay the hold acknowledge signal until through with the XPORT. The arbiter, then asserts a grant signal to the DMA controller requesting access. The arbiter may assert a grant signal to a processor core requesting access. However, the processor core's access will be stalled as long as the hold signal is asserted.

Abstract: A digital signal processing chip having a multiple processor cores with corresponding processor subsystems, a shared component, and a clock tree, is disclosed herein. A clock tree distributes clock signals to the processor cores and the shared component. The clock tree can be configured to disable one or more of the processor cores and the shared component by blocking the corresponding clock signal. This may advantageously conserve power. However, the clock tree is configured to preserve the clock signal to the shared component as long as at least one of the processor cores has not disabled the shared component. That is, to block the clock signal to the shared component, each of the processor cores must disable the shared component. The shared component may, for example, be a shared program memory or an arbiter for an external input/output port. The clock tree may include a register and a series of clock gates. Each of the clock gates blocks the clock signal when a gate signal is de-asserted.

Abstract: A multi-core digital signal processor is disclosed having a shared program memory with conditional write protection. In one embodiment, the digital signal processor includes a shared program memory, an emulation logic module, and multiple processor cores each coupled to the shared program memory by corresponding instruction buses. The emulation logic module preferably determines the operating modes of each of the processors, e.g., whether they are operating in a normal mode or an emulation mode. In the emulation mode, the emulation logic can alter the states of various processor hardware and the contents of various registers and memory. The instruction buses each include a read/write signal that, while their corresponding processor cores are in normal mode, is maintained in a read state. On the other hand, when the processor cores are in the emulation mode, the processor cores are allowed to determine the state of the instruction bus read/write signals.

Abstract: A DSP device is disclosed having multiple DMA controllers with global DMA access to all volatile memory resources in the DSP device. In a preferred embodiment, each of the DMA controllers is coupled to each of the memory buses and is configured to control each of the memory buses. A memory bus multiplexer may be coupled between the subsystem memory bus and each of the DMA controllers, and an arbiter may be used to set the memory bus multiplexer so as to allow any one of the DMA controllers to control the memory bus. The memory bus may also be controlled by the host port interface via the memory bus multiplexer. A round-robin arbitration technique is used to provide each of the controllers and the host port interface fair access to the memory bus. This approach may advantageously provide increased flexibility in the use of DMA controllers to transfer data from place to place, with only a minimal increase in complexity.

Abstract: A multi-core DSP device includes a shared program memory to eliminate redundancy and thereby reduce the size and power consumption of the DSP device. Because each of the program cores typically executes the same software program, memory requirements may be reduced by having multiple processor cores share only a single copy of the software. Accordingly, a program memory couples to each of the processor cores by a corresponding instruction bus. Preferably the program memory services two or more instruction requests in each clock cycle. Data is preferably stored in separate memory arrays local to the processor core subsystems and accessible by the processor cores via a dedicated data bus. In one specific implementation, the program memory includes a wrapper that can perform one memory access in the first half of each clock cycle and a second memory access in the second half of each clock cycle.

Abstract: An electronics testing circuit comprises a tested circuit (12) which includes testing cells (30,32) and a first transceiver (54) coupled to the cells (30,32). The first transceiver (54) is operable to transmit signals received from the testing cells (30,32) and to receive signals transmitted for the cells (30,32). A second transceiver (26) is operable to receive signals from the first transceiver (54) and send signals to the first transceiver (54). A testing device (18) is coupled to the second transceiver (26) and is operable to send signals to it for the testing cells (30,32) and receive signals from the testing cells (30,32).

Abstract: A DSP device is disclosed having multiple DMA controllers with global DMA access to all volatile memory resources in the DSP device. In a preferred embodiment, each of the DMA controllers is coupled to each of the memory buses and is configured to control each of the memory buses. A memory bus multiplexer may be coupled between the subsystem memory bus and each of the DMA controllers, and an arbiter may be used to set the memory bus multiplexer so as to allow any one of the DMA controllers to control the memory bus. The memory bus may also be controlled by the host port interface via the memory bus multiplexer. A round-robin arbitration technique is used to provide each of the controllers and the host port interface fair access to the memory bus. This approach may advantageously provide increased flexibility in the use of DMA controllers to transfer data from place to place, with only a minimal increase in complexity.

Abstract: A digital signal processing chip having a multiple processor cores with corresponding processor subsystems, a shared component, and a clock tree, is disclosed herein. A clock tree distributes clock signals to the processor cores and the shared component. The clock tree can be configured to disable one or more of the processor cores and the shared component by blocking the corresponding clock signal. This may advantageously conserve power. However, the clock tree is configured to preserve the clock signal to the shared component as long as at least one of the processor cores has not disabled the shared component. That is, to block the clock signal to the shared component, each of the processor cores must disable the shared component. The shared component may, for example, be a shared program memory or an arbiter for an external input/output port. The clock tree may include a register and a series of clock gates. Each of the clock gates blocks the clock signal when a gate signal is de-asserted.

Abstract: A multi-core digital signal processor is disclosed having a shared program memory with conditional write protection. In one embodiment, the digital signal processor includes a shared program memory, an emulation logic module, and multiple processor cores each coupled to the shared program memory by corresponding instruction buses. The emulation logic module preferably determines the operating modes of each of the processors, e.g., whether they are operating in a normal mode or an emulation mode. In the emulation mode, the emulation logic can alter the states of various processor hardware and the contents of various registers and memory. The instruction buses each include a read/write signal that, while their corresponding processor cores are in normal mode, is maintained in a read state. On the other hand, when the processor cores are in the emulation mode, the processor cores are allowed to determine the state of the instruction bus read/write signals.

Abstract: A digital signal processing system is disclosed that includes multiple processor subsystems, an external input/output port (XPORT), and an XPORT arbiter. The processor subsystems each include a processor core and a DMA controller, both of which may require access to the XPORT. The XPORT arbiter grants access by separately arbitrating between the processor cores and between the DMA controllers, and further arbitrating between processor control or DMA control of the XPORT. Upon receiving a request signal from a DMA controller, the XPORT arbiter asserts a hold signal to each of the processor cores. The processor cores respond to the hold signal by asserting a hold acknowledge signal. Note that if a processor core is currently using the XPORT, the processor core will delay assertion of the hold acknowledge signal until it is through with the XPORT. The arbiter, after receiving assertions of each of the hold acknowledge signals, then asserts a grant signal to the DMA controller requesting access.

Abstract: A multi-core DSP device includes a shared program memory to eliminate redundancy and thereby reduce the size and power consumption of the DSP device. Because each of the program cores typically executes the same software program, memory requirements may be reduced by having multiple processor cores share only a single copy of the software. Accordingly, a program memory couples to each of the processor cores by a corresponding instruction bus. Preferably the program memory services two or more instruction requests in each clock cycle. Data is preferably stored in separate memory arrays local to the processor core subsystems and accessible by the processor cores via a dedicated data bus. In one specific implementation, the program memory includes a wrapper that can perform one memory access in the first half of each clock cycle and a second memory access in the second half of each clock cycle.

Abstract: An improved microcomputer has a page register connected to a program counter in order to extend the program address range of the microcomputer. A page stack is connected to the pager register and operates in conjunction with an address stack. The page register is loaded from bits in the first word of a two word branch or call instruction in such a manner that no additional execution time is required nor are any additional instructions required to provide the extended address range. A predefined microprocessor ASIC cell is augmented by externally connecting a page register and an opcode decoder so that instruction memory address range can be expanded by paging without redesigning the microprocessor cell.