KR890000274Y1 - Interface circuit of on-screen ic and ccd - Google Patents

Abstract

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Description

Interface circuit of on-screen IC and CCU

1 is a timing chart of command bus signal transmission of an on-screen IC.

2 is a timing chart of data transmission through the IM bus of the CCU.

3 is a circuit diagram of a conventional on-screen IC and a CCU.

4 is an interface circuit of an on-screen IC and a CCU according to the present invention.

5 is a flowchart showing a program inside a CCU of a portion for transmitting command data to an on-screen IC.

* Explanation of symbols for main parts of the drawings

1: Central Processing Unit (CCU) 2: On-Screen IC

3: video signal control unit 4: audio signal control unit

1, n, m: bus

The present invention is an interface for sharing the IM bus of the central control unit (CCU) with the bus that transmits commands to the character generator circuit (on-screen IC) in a television receiver having an on-screen function. It is about a circuit.

The on-screen function of a television receiver is a function of displaying on a television screen graphically or numerically the value set by channel information and control switches such as voice mode, color, brightness, volume and sound quality.

Typically, this function is performed by using an on-screen IC controlled by a central control unit (CCU) manufactured by Inter Matall (hereinafter abbreviated as IM).

Inside the central control unit, there are a CPU, a program ROM, an inter-bus bus generator, and a port, a register, etc. for connecting to an external circuit. There are three registers to connect.

One of them is for the address, the other is for the data, and the other is for the control.

The program ROM contains a program for determining the operating function of the TV.

Stored programs also include programs that change the screen, sound quality, and volume status as the TV user manipulates it. When the user presses the operation switch, the CCU recognizes this and decides how to control it. The address of the function to be controlled is stored in the address register connected to the IM bus signal generator inside the CCU, and the amount to be controlled is stored in the data register. After saving, write IM bus signal start command to control register.

From this point on, the IM bus signal generator generates an IM bus signal obtained by converting parallel data stored in two registers into serial data.

On the other hand, the bus signal generator inside the CCU is made by the CCU manufacturer and does not describe the detailed configuration, but the CCU user only needs to understand the operation of the resistors connected to the bus signal generator described above.

The IM bus signal generated by the CCU is transferred to the video controller and the audio controller through the IM bus. When an address corresponding to each control function of the TV receiver, such as color, brightness, volume, and sound quality, is transmitted to each control unit (image control unit, voice control unit), only the corresponding control unit selects and displays screen, volume, and sound quality as continuous data after the address. It changes the state.

Because the on-screen function displays the user's operation status, the on-screen IC is also controlled by the CCU just as each controller is controlled by the CCU.

Since the control of the on-screen IC is performed as the command bus signal of the on-screen IC as shown in FIG. 1, the CCU must generate the bus signal as shown in FIG.

However, although there is an IM bus signal generation circuit inside the CCU, there is no circuit for generating a bus signal as shown in FIG. 1, so an interface circuit capable of generating such a bus signal should be added to the outside.

In other words, the IM bus signal is generated inside the CCU as shown in FIG. 2, and the signal of FIG. 1 is different because there are more strobe signals. The signal structure corresponds to that of the IM bus and the first signal when the data clock of FIG. The signal of Fig. Has similarity and the data D ₀ -D ₇ of Fig. ₁ is mapped to the address A ₀ -A ₇ of Fig. 2 so that the signal corresponding to the strobe can be added to the signal of Fig. 2 by the same.

The signal of FIG. 1 is a timing chart required for an on-screen IC and FIG. 2 is an IM bus timing chart. Since the signals required for an IM bus and an on-screen IC are fundamentally different, the on-screen command bus signal generator of FIG. In 5), the signal of FIG. 1 is generated.

Such an interface circuit is conventionally constituted by providing an on-screen command bus signal generator 5 between the on-screen IC 2 and the CCU 1, as shown in FIG.

Here, an 8-bit port is required as a path for transferring data from the CCU 1 to the mus signal generator 5, and the LSI (Large-Scale Integration) is also used to construct the on-screen command bus signal generator 5 itself. ) It takes 4-5 parts, which complicates the circuit configuration and increases the cost.

In addition, when using the on-screen control of eight ports of the CCU (1) is also a problem that the CCU is subject to a lot of restrictions to control the overall function.

Accordingly, the object of the present invention is simple and simple by utilizing the commonality between the IM bus inside the CCU and the on-screen command transfer bus without using the dedicated bus signal generator 5 of FIG. 3 used for the control of the on-screen IC. To provide a low-cost on-screen IC and CCU interface circuit.

According to an aspect of the present invention, an on-screen IC using only one port of the CCU can be used to share an existing IM bus without using a separate bus signal generator to transmit a command bus signal as shown in FIG. Interfacing with the CCU.

The objects, features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.

4 is an overall circuit diagram of the present invention, in which the data terminal of the on-screen IC 2 is connected to the IM bus (l) data terminal of the CCU 1, and the clock terminal of the on-screen IC 2 is similarly used. CLK is connected to the IM bus (n) clock terminal of the CCU (1), and is a circuit connecting the strobe STB terminal of the on-screen IC (2) to any one port of the CCU (1) have.

In such a circuit, the on-screen IC 2 is connected to the command bus (hereinafter referred to as command bus) of the on-screen IC of FIG. Is held low and data D _{0 through} D ₇ are accepted into an internal 8-bit shift register when clock CLK goes from low to high.

The data D ₀ -D ₇ received in the shift register are judged to be valid instructions when the strobe signal STB becomes high level and finally operate inside the on-screen IC 2.

Therefore, in order for the on-screen IC 2 to recognize the command, a signal is applied to the clock and data lines so that an 8-bit signal is stored in the shift register inside the on-screen IC 2, and then the strobe signal STB is output. You have to. (How to output the signal is explained later).

On the other hand, the video and audio signal controllers 3 and 4 analyze the address information A ₀ -A ₇ of the data as shown in FIG. 2, and if the corresponding address is passed, the data information D ₀ delivered after the address information _. It operates in accordance with -D ₇ , no corresponding address is passed, and no action is taken regardless of data information D ₀ -D ₇ . Therefore, when sending a command signal to the on-screen IC 2, the addresses specified in the video signal controller 3 and the audio signal controller 4 should not be used.

Where the on-screen IC 2 Since the terminal is grounded, the on-screen IC 2 only needs eight clocks and the commonly used data and strobe signals to recognize the command. Eight clocks and data use the interval of data D ₀ -D _{7 in} the IMbus output signal of FIG.

8-bit data which is finally transmitted to the inside-screen shift register IC (D ₀ -D - D ₀ -D The IM bus using an interval of ₇ is transmitted when the address D ₀ -D ₇ of the information on whether anything regardless ₇ ) This is possible because only one remains.

The reason why only the last 8-bit data transferred in this way remains is because the data previously received by the shift register operation is pushed out by the data received later.

Since only the D ₀ -D ₇ of the IM bus is required for the on-screen IC 2 to recognize the command, an address not used for the video signal controller 3 and the audio signal controller 4 can be used.

That is, on-screen command data is delivered regardless of any of addresses A ₀ -A ₇ in FIG.

Here, the strobe signal STB is used as a means for preventing the on-screen IC 2 from being affected when transmitting data to the audio and video signal controller.

The strobe signal STB is output at the port A of the CCU 1 by the internal program of the CCU 1.

As for the internal program of the CCU 1, a program for transmitting data to the video and audio signal controllers has already been created to reproduce the basic functions of the TV, as shown in the flowchart shown in FIG. 5, and the on-screen command data (D _0- In order to transmit D ₇ ), it is necessary to execute a program already created to control video and audio signals, and then add a program that outputs the strobe signal STB.

In order to transmit on-screen commands, the command data is output using a program that exports audio and video signals as IM bus signals.

In this case, since the data line and the clock line are connected to the IM buses l and n, the on-screen IC 2 can store 8-bit data in the shift register inside the on-screen IC 2.

In other words, after transmitting data D ₀ -D ₇ using IM buses l and n, the strobe signal STB is output as described above. When the strobe signal STB is output, the on-screen IC 2 recognizes it as a valid command and executes an operation.

The register for address shown in FIG. 5 is a register for IM bus address (A ₀ -A ₇ ) connected between the CPU and the IM bus signal generation circuit in the CCU (1), and the register for data is also inside the CCU (1). Is a register for IM bus data (D ₀ -D ₇ ) connected between the CPU and the IM bus signal generator.

In addition, the control register is an IM bus signal generator control register connected between the CPU and the IM bus signal generation circuit in the CCU 1, and when a start command is written in this register, the signal is transmitted with the timing shown in FIG.

When the CPU executes the program up to point A in the flowchart, the bus signal as shown in FIG. 2 is transmitted outside the CCU 1.

When the transfer is completed, data D ₀ -D ₇ are stored in the internal shift register of the on-screen IC 2.

At point B where the CCU 1 outputs a high level to the port A, the strobe signal STB of the on-screen IC 2 becomes high level, and then on-screen when the point C is output to the point A where the low level is output to the port A. One complete command is sent to the IC 2.

As described above, according to the circuit of the present invention, it is possible to share an existing IM bus by adding only one port to the CCU without using a separate bus signal CCU generator to transmit a command bus signal. -The interface between the screen IC (2) and the CCU (1) is not a single hardware component, there is a practical advantage that the circuit is simplified and the cost is reduced.

Claims (1)

CPU, PROM, IM bus signal generator, CCU (1) including a port and a register for connecting to an external circuit, and the IM bus signal generated by the CCU (1) to the video and audio control unit (3, 4) In the character generator circuit of a television receiver having an IM bus (1, n, m) for transmission and an on-screen IC (2) having an on-screen function and controlled by the CCU by a command bus signal, The data terminal Data of the on-screen IC 2 is connected to the IM bus data terminal of the CCU 1, and the clock terminal CLK of the on-screen IC 2 is connected to the IM bus clock terminal of the CCU 1. And the strobe terminal STB of the on-screen IC (2) is connected to either port of the CCU (1).