KR19990005569A - How to protect your monitor - Google Patents

Abstract

The present invention relates to a DDC monitor, the method of the present invention, the microcomputer detects the state of the SDA signal line and the SCL clock line, if the SCL clock line is low state, and if the SDA signal line is low state And applying an active high square wave signal to the SDA signal line to restore the SDA signal line to a normal state.

Therefore, the present invention displays the communication failure caused by the SCL clock line in the I ² C communication channel between the microcomputer and its peripheral integrated circuits so that the user can take necessary measures, and if the communication failure occurs due to the SDA signal line, By initializing the SDA signal line, the SDA signal line is restored to its normal state, thereby protecting the monitor from abnormal operating conditions.

Description

How to protect your monitor

The present invention relates to a DDC monitor, and more particularly, to a method of protecting a monitor by detecting and initializing a communication failure between a microcomputer transmitting and receiving data through an I ² C communication channel and a peripheral integrated circuit.

In addition to the recent trend of larger monitors, the 'PLUG PLAY' method for increasing user convenience has been implemented in monitors. Here, 'plug and play' literally means that when you attach a new board or peripheral to your computer, simply plug in a cable and plug in the power, and the computer automatically reconfigures your environment and makes it ready for immediate use. It means.

To this end, conventional monitors simply receive signals from the computer and display them, while plug-and-play monitors can exchange information with the computer. The monitor can provide information on the optimal available modes and adjustments to the computer. Must be able to provide Therefore, plug and play on a monitor should connect the signal cable to the computer, operate the monitor, automatically select the best mode for the computer to use, and provide the user with the best calibrated screen.

In order to apply the plug and play function to the monitor, a protocol for storing its own information on the monitor and transmitting it to a computer must be preceded.

Therefore, the Video Electronic Standards Association (VESA), a non-profit corporation established among US computer and peripheral companies, has established a standard for the display data channel (DDC) transmission method for plug and play monitors.

Here, the DDC transmission method defines a communication channel between the computer and the monitor, and refers to a protocol for transmitting the monitor information stored in the monitor to the computer or changing the monitor information using a keyboard mouse.

In other words, the existing monitor is only displayed by the one-way signal of the video card, but by using the DDC, the information and capabilities of the display can be communicated with the computer, and the integrated communication of the computer, monitor, keyboard, and mouse is possible. Done. This DDC monitor is convenient because it can be used immediately without connecting the display resolution setting process even if there is no manual of each product at the time of purchase.

On the other hand, the DDC monitor has a one-way to provide the monitor information to the computer and a bi-directional to provide information to the monitor in the computer.

For example, 'DDC1' is a one-way transmission method that provides monitor information to a computer as the most basic communication method, and the computer cannot control the information transmission. When these monitors are connected to a computer and the monitor is powered on, the monitor provides information to the computer using the vertical frequency as the transmission clock, and the computer provides the optimum signal for the monitor to display in a mode that matches the information obtained from the monitor. to provide.

In addition, 'DDC2B' is a bi-directional transmission method that enables a monitor and a computer to communicate with each other and is based on the I ² C protocol.

'DDC2AB' is a full bidirectional transmission method, which frees the exchange of information between the monitor and the computer, and uses the ACCESS bus to modify the monitor information. Therefore, the DDC2AB monitor can directly connect a peripheral device, a keyboard, and a mouse, which are conventionally connected to a computer.

Table 1 shows the communication channel connections compared with the conventional VGA connection.

PIN number VGA DDC-1,2 Disp DDC-1 Host DDC2 Host One R R R R 2 G G G G 3 B B B B 4 ID bit 2 Optional ID bit 2 ID bit2 5 Test Return Return Return 6 R return R return R return R return 7 G return G return G return G return 8 B return B return B return B return 9 NC + 5V load + 5V supply + 5V supply 10 Sync return Sync return Sync return Sync return 11 ID bit 0 Optional ID bit 0 ID bit 0 12 ID bit 1 SDA Data SDA 13 H.sync H.sync H.sync H.sync 14 V.sync V.sync (VCLK) V.sync V.sync 15 ID bit 3 SCL ID bit3 SCL

As shown in Table 1, + 5V provided by the computer is connected through pin 9 in the case of DDC in the 15-pin desub connector, and pin 12 (SDA) is synchronized with the vertical synchronization clock (V.sync) of pin 14 in DDC1. The data is transmitted from the monitor to the computer through serial data). In DDC2, data can be transferred in both directions through pin 12 (SDA). Pin 15 (SCL: serial clock) is the clock signal line.

1 is a circuit diagram illustrating a communication connection state of a microcomputer of a general DDC monitor and an integrated circuit (IC) thereof, and the microcomputer 11 of the DDC monitor is a peripheral integrated circuit, for example, an OSD IC 12, deflection. The SDA signal line and the SCL clock line are used to exchange data with the circuit IC 13, the video preamplifier IC 14, and the like.

The SDA signal line and the SCL signal line are protected from impact such as static electricity by the zener diodes ZD1 and ZD2, and are pulled up to the Vcc driving power supply through the pull-up resistors R3 and R4, and through the capacitors C3 and C4. Noise is to be removed. In the communication channel, the microcomputer 11 performs a protocol according to the DDC1 or DDC2 to process the communication function between the monitor and the computer. An EEPROM 15 for storing data transmitted during communication with the computer is provided. Added.

Here, the SDA signal line and the SCL clock line are applied with a high level or a pulse signal is transmitted in a normal state. When the SDA signal line and the SCL clock line transition to a low level, smooth data transfer is not performed.

That is, the SDA signal line and the SCL clock line may abnormally operate in noise during communication, or may transition to a low level due to an impact by an atmospheric arc, and at this time, I ² C communication between the microcomputer and the peripheral integrated circuit may be smooth. There is a problem that the monitor set itself is broken without being made.

Accordingly, the present invention has been made to solve the above problems of the prior art, and when a problem occurs in the I ² C communication channel connecting the microcomputer and the peripheral integrated circuit, it is quickly detected and initialized to monitor from the communication failure. Its purpose is to provide a method of protection.

The circuit of the present invention for achieving the above object, the step of detecting the state of the SDA signal line and the SCL clock line, the microcomputer;

Displaying the SCL clock line when it is low;

And if the SDA signal line is in a low state, applying an active high square wave signal to the SDA signal line to restore the SDA signal line to a normal state.

1 is a circuit diagram showing a communication channel connection state between a micom and a peripheral integrated circuit of a general DDC monitor;

2 is a block diagram showing a monitor protection device according to the present invention;

3 is a flowchart illustrating a monitor protection method according to the present invention.

Explanation of the symbols according to the main parts of the drawings

21: Micom 12: OSD IC

13: Deflection Circuit IC 14: Video Preamplifier IC

15: EEPROM 22: light emitting diode

Hereinafter, an embodiment according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a circuit diagram illustrating a monitor protection circuit according to the present invention, wherein peripheral integrated circuits such as the microcomputer 21 and the OSD IC 12, the deflection circuit IC 13, and the video preamplifier IC 14 are clocked SCL. The data is exchanged through a line and an SDA signal line. When the SCL clock line transitions to a low level, the microcomputer 21 outputs a control signal to the first control terminal P3 to turn on the light emitting diode 22. To display.

In addition, the microcomputer 21 senses the states of the SCL clock line and the SDA signal line through the first detection terminal P1 and the second detection terminal P2. When the SDA signal line transitions to a low level, the micom ( 21) outputs a square wave signal to the second control terminal (P4) so that the SDA signal line is in a normal state.

The operation and effects of the present invention configured as described above are as follows.

3 is a flowchart illustrating a micom protection method according to the present invention. The present invention will be described with reference to the block diagram of FIG. 2 and the flowchart of FIG. 3.

Step 31 is a step of reading the SCL clock line and the SDA signal line through the first detection terminal P1 and the second detection terminal P2 before the microcomputer 21 exchanges data with the peripheral integrated circuit.

Step 32 is a step of detecting whether the SCL clock line read through the first detection terminal P1 is pulled up to a 'high' level. If the SCL clock line is pulled up to a 'high' level, the operation proceeds to step 33. Proceed to step 37 if the SCL clock line is not at the 'high' level.

Step 33 is a step of detecting whether the SDA signal line read through the second detection terminal P2 is pulled up to the 'high' level in step 31. If the SDA signal line is the 'high' level, the process proceeds to step 34. If the SDA signal line is not at the 'high' level, the process proceeds to step 35.

Step 34 is performed when both the SCL clock line and the SDA signal line read out in step 31 are pulled up to a normal 'high' level, in which the microcomputer 21 and its peripheral integrated circuit are connected through an I ² C communication channel. Data transfer between them takes place.

Step 35 is a step that proceeds when the SDA signal line read out in step 31 is not at the 'high' level, that is, when the SDA signal line is not in a normal state. Restoring the SDA signal line to a normal state.

Step 36 is a step of reading whether the SDA signal line has been restored to a normal state after outputting the square wave signal to the SDA signal line in step 35, by reading whether the SDA signal line is pulled up to a 'high' level, Detect if it is normal.

Step 37 is a step that proceeds when the SCL clock line is not in the normal state in step 32 or the SDA signal line is not restored to the normal state in step 36, the microcomputer 21 is controlled through the first control terminal (P3) The output of the signal causes the light emitting diode 22 to light up to display that a communication failure has occurred in the I ² C communication channel.

As described above, the present invention displays a communication failure caused by the SCL clock line in the I ² C communication channel between the microcomputer and its peripheral integrated circuits, thereby enabling the user to take necessary measures, and by using the SDA signal line. When a communication failure occurs, the SDA signal line is initialized to restore the normal state, thereby protecting the monitor from abnormal operation.

Claims (1)

Detecting a state of the SDA signal line and the SCL clock line by the microcomputer; displaying the SCL clock line when the SCL clock line is low; and applying an active high square wave signal to the SDA signal line when the SDA signal line is low; And the signal line is restored to a normal state.