Digital signal processing system

Abstract: A digital signal processing system for effectively accessing a large amount of memory data having a delay time larger than a system clock by means of time sharing of the pipeline method and by system clock of one cycle of single high speed digital signal processor. A digital address signal is output from the high speed signal processor (1) into a number of memories (3A - 3E) through a demultiplexer (2). A data reading from each memory is read into a number of registers (5A - 5E) each corresponding to a memory through a multiplexer (4), and is fedback to the digital signal processor.

Description: The present invention relates to a digital signal processing system, and more particularly to a high speed digital signal processing system for effectively accessing a large amount of memory information having a delay time larger than a system clock by means of time sharing of the pipeline method and by the system clock of one cycle of a single high speed digital signal processor. A digital signal processing system for converting analog signals into digital signals includes a memory for saving data and a device for operating the digital signal. The system obtains a result by operation of the data. However, the overall processing speed has heretofore been limited because the time delay for accessing the data in the memory is larger than that of the operation device. In general, a conventional digital signal processing system is constructed to use only one memory to one digital signal processor. Therefore, a system clock period larger than the data access time delay in the memory is required since the system clock of the digital signal processor is set on the basis of data access time delay in memory. The document Computer Architecture News, 18 th Annual Symposium or Computer Architecture, 19 May 1991, No. 3, New York, US, B. RAMAKRISHNA RAU: "Pseudo-Randomly Interleaved Memory, pages 74-83 discloses various interleaving schemes and corresponding memory architectures used in computer systems such as super computers. The signal processing system using the digital signal processor must use real time processing, which is an enormous operation. Therefore, the digital signal processor for real time processing is restricted and is difficult to embody due to the influence of the memory with a very large time delay. Thus, for a long time, digital signal processing systems have adopted a form in which a plurality of digital signal processors are connected in parallel to a plurality of memories. An object of the present invention is to provide an improved digital signal processing system that is capable of accessing effectively a plurality of memories, which are connected in parallel to a single digital signal processor by a method involving time sharing of a pipeline. According to the present invention there is provided a digital processing system comprising: a digital signal processor coupled to a high speed address bus and a high speed data bus, said digital signal processor generating a series of memory addresses on the high speed address bus synchronized to a system clock; an address demultiplexer receiving the memory address series and sequentially distributing each individual address to one of a plurality of low speed address buses, said each low speed address bus having lower speed than said high speed address bus; a plurality of memories having data access delay time greater than a period of the system clock, each memory coupled to one of the low speed address buses and coupled to one of a plurality of low speed data buses for transferring data from said each memory, said each low speed data bus having lower speed than said high speed address bus; a data multiplexer receiving data from each memory through each low speed data bus and multiplexing the data; and a plurality of registers for temporarily storing the data multiplexed by said data multiplexer and supplying the data to said digital signal processor through the high speed data bus. According to a preferred embodiment of the present invention, the system clock synchronizes the digital signal processor, demultiplexer, and multiplexer. It is thereby possible to effectively access a plurality of memories by means of time sharing. As a result, the system performance restricted within large memory access time delay is improved. According to the present invention, in a further aspect, there is provided a digital processing method comprising generating, by a digital signal processor, a series of memory addresses synchronized to a system clock; applying the addresses at high speed to an address demultiplexer and causing said address demultiplexer to sequentially distribute each individual address, at a low speed, over one of a plurality of low speed connections to a respective one of a plurality of memories, each memory having data access delay time greater than a period of the data clock, and each memory being coupled to one of the low speed connections; supplying data from each memory at low speed to a data multiplexer; multiplexing the data; temporarily storing the multiplexed data in a plurality of registers; and supplying the data, at high speed, from the registers to the digital signal processor. Embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings, in which; Figure 1 is a block diagram of a digital signal processing system in accordance with an embodiment of this invention; and Figure 2(A) to 2(K) are waveforms showing the operation of the circuit shown in Figure 1. Referring to Figure 1, the system comprises a digital signal processor 1 generating address signals A, B, C, D and E in accordance with a system clock SCK, having a high speed operational function. The address signals A, B, C, D and E of the digital signal processor 1 are gradually divided and suppled to a memory block 3 connected in parallel through a 1x5 demultiplexer 2. The memory block 3, for example, consists of five memories, generally 3A to 3E. Generally, the processing speed of each memory (3A to 3E) is slower than the digital signal processor 1. Each memory outputs data corresponding to the address of each memory in response to each address signal (A to E). Each portion of data is selectively stored in a respective one of five registers (5A to 5E) corresponding to each memory through a 5x1 multiplexer 4. The data temporarily stored at said registers (5A to 5E) is fedback to the digital signal processor 1. In the illustrated embodiment, the memory block 3 consists of five memories. The number of memories is determined by the value resulting from dividing the data access delay time of one memory by a system clock period of the digital signal processor. For example, in the case where the data access delay time of the memory is 100 nanoseconds and the system clock period of the digital signal processor is 20 nanoseconds, five memories can be established in the memory block 3. Figures 2(A) to 2(K) are waveforms illustrating the signals output from the components of Figure 1. The system clock of 20ns is input periodically to the digital signal processor 1, and then the digital signal processor 1 outputs address signals 1A to 1E corresponding to the system clock SCK. The waveforms of the system clock SCK is shown in Figure 2(A). Figures 2(B) to 2(F) illustrate address signals 1A to 1E which access five memories 3A to 3E. First, the first memory 3A is accessed by the signal 1A since the 1x5 demultiplexer sequentially outputs the address signals. Successively, the second to fifth memories 3B to 3E are accessed by the signals 2B to 2E per 20ns, respectively. After 100ns, referring now to Figures 2(G) to 2(K), it may be seen that the memories 3A to 3E are sequentially output the data D1 to D5 corresponding to the address of each memory per 20ns. For example, the third memory 3C is output the data D3 after 130ns. At the same time, the data D1 to D5 are sequentially stored in the registers 5A to 5E respectively, through the 5x1 multiplexer 4. Similarly, the data from the memory is gradually stored in the register 5 at intervals of 20ns. The switching time of the multiplexer which is gradually selected and output is equal to the system clock SCK and the demultiplexer 2. The data stored in the registers 5A to 5E is fed back to the digital signal processor 1. Successively, the memory block 3 may be input new address signals 1A' to 1E' and output new data D'1 to D'5. This then repeats. According to the present invention, a memory can be used in this system even if the memory is of relatively low processing speed compared to the digital signal processor. If the system clock cycle is intended to be α times and the memory access time delay is intended to be β times, the address signals 1A, 1B, 1C, 1D and 1E are available for α, 2α, 3α, 4α, and 5α times, respectively. Also, the effective times of the data D1, D2, D3, D4, and D5 are available for β, α+β, 2α+β, 3α+β, and 4α+β, respectively. Accordingly, it is possible to access the memory having a delay times β larger than α cycle within one system clock cycle α. As described above, in embodiments of the present invention there can be accessed the memory information by the system clock of one cycle as a consequence of using one digital signal processor connected in parallel to the plurality of memories. As a result, high speed processing is enabled despite the time delay of the memory. Thus, the invention is useful for a digital signal processing system having a large amount of memory to process a large amount of data within a short time.

Claims: A digital processing system comprising: a digital signal processor (1) coupled to a high speed address bus and a high speed data bus, said digital signal processor generating a series of memory addresses on the high speed address bus synchronised to a system clock; an address demultiplexer (2) receiving the memory address series and sequentially distributing each individual address to one of a plurality of low speed address buses synchronised to the system clock, said each low speed address bus having lower speed than said high speed address bus; a plurality of memories (3A - 3E) having data access delay time greater than a period of the system clock, each memory (3A-3E) coupled to one of the low speed address buses and coupled to one of a plurality of low speed data buses for transferring data from said each memory, said each low speed data bus having lower speed than said high speed address bus; a data multiplexer (4) receiving data from each memory (3A-3E) through each low speed data bus and multiplexing the data synchronised to the system clock; and a plurality of registers (5A - 5E) for temporarily storing the data multiplexed by said data multiplexer (4) and supplying the data to said digital signal processor (1) through the high speed data bus. A digital processing system according to Claim 1, wherein the number of said memories (3A-3E) is approximately equal to the ratio of the data access delay time to the period of the system clock. A digital processing method comprising generating, by a digital signal processor (1), a series of memory addresses synchronised to a system clock; applying the addresses at high speed to an address demultiplexer (2) and causing said address demultiplexer (2) to sequentially distribute each individual address, at a low speed, over one of a plurality of low speed connections to a respective one of a plurality of memories (3A-3E) each memory (3A-3E) having data access delay time greater than a period of the data clock, and each memory (3A-3E) being coupled to one of the low speed connections; supplying data from each memory at low speed to a data multiplexer (4); multiplexing the data; temporarily storing the multiplexed data in a plurality of registers (5A-5E); and supplying the data, at high speed, from the registers (5A-5E) to the digital signal processor (1).

Inventors: KIM DONGHOI, LEE BANGWON, KIM, DONGHOI, LEE, BANGWON
Applicants: SAMSUNG ELECTRONICS CO LTD, SAMSUNG ELECTRONICS CO., LTD.
Application year: 1993
Main classification: G06F12
IPC codes: G06F12, G06F17, G06F13