Electrical computers and digital data processing systems: input/ – Input/output data processing – Direct memory accessing
Reexamination Certificate
2001-01-25
2004-04-27
Gaffin, Jeffrey (Department: 2182)
Electrical computers and digital data processing systems: input/
Input/output data processing
Direct memory accessing
C710S021000, C710S023000, C710S026000, C708S303000, C708S523000
Reexamination Certificate
active
06728796
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a digital memory arrangement and signal processing arrangement, in particular a filter arrangement, having a plurality of filter modules for digital signal processing/storing, in particular filtering, of input values or input signals. The digital signal processing arrangement includes a memory area and at least one multiplier-accumulator (MAC) which has at least one multiplier and at least one adder. The input values, coefficients, in particular fixed filter coefficients, and output values of the signal processing arrangement can be stored in the memory area and called up again therefrom as needed. The multiplier forms products, in particular partial products for all filter modules, from the input values and coefficients, and the adder forms sums of the products, in particular of the partial products of all filter modules, as output values or output signals of the signal processing arrangement.
The present invention also relates to a method of storing values and of digital signal processing, in particular filtering, of input values or input signals in a digital filter arrangement. The input values, coefficients, in particular fixed filter coefficients, and output values of the memory arrangement or signal processing arrangement are stored in a memory area and called up again therefrom as needed. Products, in particular partial products for all filter modules, are formed from the input values and coefficients and sums of the products, in particular partial products of all filter modules, are formed in a multiplier-accumulator (MAC) of the signal processing arrangement as output values or output signals of the signal processing arrangement.
BACKGROUND INFORMATION
The most recent trend increasingly calls for digital, rather than analog, signal processing. The advantages of digital signal processing are the higher degree of accuracy and reproducibility, as well as reduced sensitivity to disturbances. The disadvantage is the higher circuitry cost, which, however, is becoming less and less important with the increasing degree of integration of digital circuits.
In digital signal processing, discrete sequences of digits (sampled and quantized signals), rather than continuous signals, are processed. To the degree to which digital signals are being digitally processed, digital signal processing arrangements, for example, filter arrangements and suitable memory arrangements, are also increasingly being used. Certain frequencies are eliminated or suppressed from the signal by digital filtering in order to improve the signal
oise ratio.
In motor vehicle controllers, filtering of the input signals or discrete input values is required for some engine control functions, for example. The controller is used for controlling certain functions in a motor vehicle, for example, of the internal combustion engine, the transmission, the brakes, or the air conditioning/heating. The controller has a microcontroller containing a processor. A control program is executed in the processor in order to perform the function of the controller. In executing the control program, input signals are processed and appropriate control commands are generated.
Digital signal processing, in particular filtering, of input values is relatively time- and computation-intensive. Therefore, it is known from the related art that digital signal processing, for example, digital filtering, of input values can be performed using a digital signal processor (DSP). A DSP can perform certain functions automatically, i.e., without support by the processor of the controller. The use of a DSP for digital signal processing, in particular filtering, of the input values has the advantage that digital signal processing, i.e., filtering, takes place without placing any load on the higher-level processor of the controller. The processor remains entirely available for performing control tasks. The use of a DSP for digital signal processing, in particular filtering, of the input values has the disadvantage that the DSP has a complex design and therefore its integration in a controller is cost- and time-intensive.
SUMMARY OF THE INVENTION
From the above disadvantages of the related art results an object of the present invention: to perform digital signal processing, in particular filtering, of input values as rapidly and reliably as possible without, however, the digital signal processing, i.e., filtering, placing extra load on a processor that is on a level higher than that of the signal processing arrangement, in particular the digital filter, for signal processing.
In order to achieve this object, the present invention proposes, based on the digital signal processing arrangement, in particular a filter arrangement, that the digital signal processing arrangement, i.e., filter arrangement, have a direct memory access (DMA) controller for coordinating data transmission of coefficients, in particular filter coefficients, input values or input signals, and output values or output signals between the multiplier-accumulator (MAC) and the memory area.
In the following, a filter arrangement will be described in detail. Further embodiments, in particular, the exemplary embodiment shown, however, should also be understood as referring generically to a signal processing arrangement or a memory arrangement having a signal processing module according to the present invention.
The design and the function of DMA controllers can be found in a plurality of manuals and specialized journals. In this respect, reference is made, for example, to Tietze, Ullrich: Halbleiter-Schaltungstechnik (Semiconductor Circuit Technology) U. Tietze, Ch. Schenk, 9th ed., Springer Verlag, 1989, pp. 704-707. A DMA controller has one or more DMA channels over which data transmission takes place from a memory area to any module of a microprocessor. In contrast to data transmission via an interface, where a plurality of commands is to be executed for transmitting one bit, which requires a plurality of clock cycles of the central processing unit (CPU) of the higher-level microprocessor, in the case of data transmission using the DMA controller, data transmission is only initiated by the CPU and the filtered output values are read from the memory area after filtering. Data transmission of the filter coefficients, input values, and the output values is coordinated by the DMA controller so that all of the digital signal processing, in particular filtering of the input values, takes place almost without using any processing time of the central processing unit of the microprocessor.
Thus, according to the present invention, a microprocessor of a signal processing device (e.g., a vehicle controller) of a higher level than the signal processing arrangement, in particular the filter arrangement, is extended by a multiplier-accumulator (MAC) having at least one multiplier and at least one adder, as well as a direct memory access (DMA) controller. The MAC and DMA controller extension of the microprocessor has a particularly simple structure and can be integrated into the higher-level signal processing device without considerable cost or effort.
The microprocessor is, for example, a component of a controller for a motor vehicle that is used for controlling certain functions in the motor vehicle. The controller processes, within the framework of vehicle function control, analog and/or digital signals. For certain control functions of the internal combustion engine, the signals are filtered. For this purpose, the analog input signals are converted into digital input values in an analog-digital converter (ADC) or the digital input values are used directly if they are available. The digital input values are stored in the memory area and are transmitted from there into the MAC via the DMA channel(s). In the MAC, the filtered output values are calculated and stored again in the memory area via the DMA channels. From there the output values are picked up by the microprocessor of the controller as filtered signal values.
According to an advantageous
Aue Axel
Martin Dirk
Gaffin Jeffrey
Kenyon & Kenyon
Peyton Tammara
Robert & Bosch GmbH
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