JP3820135B2 - Printed wiring board - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a printed wiring board that enables waveform shaping of signals on a board in a printer controller having an additional memory slot.
[0002]
[Prior art]
In a printer controller board (printed wiring board) on which an additional memory connector is mounted, the signal waveform on each connector varies depending on the number of connectors mounted and the mounting positions thereof. Here, when the frequency of the signal on the printed wiring board is low, there is often no problem. However, when the frequency of the signal on the printed circuit board becomes high, such as 50 MHz or higher, it is necessary to consider the transmission line in the digital circuit as an analog distributed constant circuit. This is to prevent malfunction of the printed circuit due to reflection on the signal on the printed circuit board due to the difference in characteristic impedance, and overshoot, undershoot and shoulder. Conventionally, in order to prevent signal reflection, the signal is terminated by the Thevenin termination or the like.
[0003]
[Problems to be solved by the invention]
However, in order to terminate all signals due to an increase in the number of pins of the connector, an increase in the mounting area and the number of components cannot be avoided, and thus the cost must be increased.
[0004]
The present invention has been made in view of the above problems, and causes the malfunction by changing the characteristic impedance of the transmission line (switching the transmission line) by using the memory detection means and changing the characteristic impedance of the transmission line depending on the mounting state and the operating state of the memory. The purpose of this is to obtain a highly reliable waveform with reduced cost.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 detects the presence / absence of the signal processing means and the extension memory connected to the extension memory connector and also detects the access speed of the signal processing means to the corresponding extension memory. to the memory detection unit, connected to the connector for expansion memory, and a transmission line control unit which switches on the basis of a plurality of transmission lines having different characteristic impedances from each other on the detection result of the memory detection unit, the memory detection unit, signal processing A printed wiring board having a function of holding data of access speed to the corresponding additional memory of the means is the main feature.
[0006]
The invention according to claim 2 is characterized in that, in the printed wiring board according to claim 1, the memory detector has a printed wiring board having a nonvolatile memory in order to retain access speed data to the corresponding additional memory. And
[0007]
In the printed circuit board according to claim 2, when there is no change in the presence or absence of the additional memory, the printed circuit board using the access speed data held in the nonvolatile memory is mainly used. Features.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a printer controller mounted on a printed wiring board according to the present invention. In the figure, reference numeral 101 denotes a CPU which performs overall system control, image processing, and the like. A ROM 102 stores programs executed by the CPU 101, various parameters, and the like. Reference numeral 103 denotes a RAM which stores control data, image data generated by processing the print data by the CPU 101, and the like for use as a work for image processing. A host I / F 104 exchanges print commands and commands with the host. Reference numeral 105 denotes an engine I / F which is connected to the printer engine in order to send commands and print data. A memory detection unit 106 is connected to a plurality of expansion memory connectors, and detects the presence / absence of the expansion memory, the operation speed, and the like. Reference numeral 107 denotes a transmission line control unit, which determines the result of the memory detection unit 106 and determines the type of transmission line connected to the connector.
[0009]
FIG. 2 is a diagram illustrating a connection state of the memory detection unit, the transmission line control unit, and the connector. Three transmission lines (signal lines) 110, 111, and 112 having characteristic impedances A, B, and C are connected between the transmission line control unit 107 and the plurality of additional memory connectors 108 and 109, respectively. In the example of the present invention, a plurality of transmission lines (signal lines) using the transmission line control unit 107 depending on the operating speed of the memory, the presence / absence of the memory, and the manufacturer of the memory module among the information obtained by using the additional memory detection unit 106. One of 110, 111, and 112 is selected and operated to switch.
[0010]
FIG. 3 is a flowchart showing a first example of transmission line switching control. For example, when a memory module is mounted on the expansion memory and the memory module is accessed at 100 MHz, the memory detection unit 106 acquires this information (S1), and maintains the access speed in the memory detection unit 106 Data is stored in the part (S2). The transmission line control unit 107 uses data stored in the access speed holding unit. For example, as shown in FIG. 2, connectors 108, 109 are used for transmission lines (signal lines) 110, 111, 112 having three types of characteristic impedances. In the case of operation at 66 MHz, the transmission line 110 with the characteristic impedance A in the case of operation at 66 MHz, the transmission line 111 with the characteristic impedance B in the case of 100 MHz (100 MHz in S3), and the case of 133 MHz (133 MHz in S3). Performs switching control like the transmission line 112 of the characteristic impedance C, and operates so as to be connected by each characteristic impedance.
[0011]
FIG. 4 is a flowchart showing a second example of transmission line switching control. Information obtained in the memory detection unit 106 is stored in the nonvolatile memory of the access speed holding unit in the memory detection unit 106 (S1, S2). Using this non-volatile memory data, each characteristic impedance is changed (S3 to S5).
[0012]
FIG. 5 is a flowchart showing a third example of transmission line switching control. The memory detection unit 106 detects the presence / absence of connection in each of the connectors 108 and 109 (S1, S2). If there is no change in the presence / absence of connection (Y in S3), the data of the nonvolatile memory of the access speed holding unit in the memory detection unit 106 is used to change the characteristic impedance (S4). ). If the state is not the same as the previous time (N in S3), the memory access speed is confirmed (S5) and stored in the nonvolatile memory (S6).
[0013]
【The invention's effect】
According to the first aspect of the present invention, in order to detect the access speed of the memory module by the memory detector and store the data in the memory module, when detecting the presence / absence of the memory again and determining the transmission line, Data can be recalled at high speed, and the time required to connect to a transmission line having an optimum characteristic impedance can be shortened.
[0014]
According to the second aspect of the present invention, since the memory detector detects the access speed of the memory module and stores the data in the nonvolatile memory of the access speed holding unit, the access speed even when the power is turned off and on. Can be called at high speed.
[0015]
According to the third aspect of the present invention, when the power is turned on, the memory detection unit checks the presence or absence of the additional memory, and if there is no change in the additional memory, the access speed data stored in the internal nonvolatile memory is stored. By using it, the time from turning on the power to determining the characteristic impedance can be shortened.
[Brief description of the drawings]
FIG. 1 is a block diagram of a printer controller mounted on a printed wiring board according to the present invention.
FIG. 2 is a diagram illustrating a connection state of a memory detection unit, a transmission line control unit, and a connector.
FIG. 3 is a flowchart showing a first example of transmission line switching control;
FIG. 4 is a flowchart illustrating a second example of transmission line switching control.
FIG. 5 is a flowchart showing a third example of transmission line switching control;
[Explanation of symbols]
101 CPU
106 Memory Control Unit 107 Transmission Line Control Unit 108, 109 Connectors 110-112 Transmission Line

Claims (3)

Signal processing means;
While detecting the presence or absence of additional memory connected to an expansion memory connector, a memory detection section for detecting the access speed to the corresponding expansion memory of the signal processing means, connected to the connector for the additional memory, different characteristic impedances and a said memory detecting unit switches on the basis of the detection result transmission line controller plurality of transmission lines with the memory detection section holds the data access speed to the appropriate expansion memory of the signal processing means A printed wiring board characterized by having a function of placing. 2. The printed wiring board according to claim 1, wherein the memory detection unit has a nonvolatile memory in order to hold data of access speed to the corresponding expansion memory. The extension to the case of the presence of the memory there are no changes, the printed wiring board according to claim 2, wherein the use data access speed that is held in the nonvolatile memory.

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