JPH08214221A - Serial communication equipment - Google Patents

Abstract

PURPOSE: To improve the quantity of a picture by preventing the generation of disturbance or noise on a screen. CONSTITUTION: A start signal and data out of a serial signal are respectively transmitted from a start signal generating circuit 1 and a data transmitting circuit 2 respectively in synchronism with a synchronizing signal 6. Then a stop signal out of the serial signal is transmitted by a stop signal generating circuit 3 in synchronism with the signal 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a serial communication device for controlling various functions by serial communication in a television receiver or the like.

[0002]

2. Description of the Related Art Recently, a television receiver such as a color television receiver (hereinafter, abbreviated as a television) has introduced many circuits controlled by serial communication.
The role of serial communication has become important.

In conventional serial communication, a start signal, data and a stop signal are generally sent at once. For example, in a TV, serial control sends control data to a circuit controlled by the data asynchronously with a TV sync signal, or in synchronization with a TV vertical sync signal to generate a start signal, data, and a stop signal. Is transmitted at one time, or as disclosed in Japanese Patent Laid-Open No. 4-336878, the vertical synchronizing signal of the television is superposed on the serial signal, and the serial signal is separated on the receiving side to synchronize with the vertical synchronizing signal. I was controlling.

Hereinafter, conventional serial communication will be described with reference to the drawings, taking serial communication in a television as an example. FIG. 5 is a block diagram showing a configuration of a conventional serial communication device in a television, FIG. 6 is a timing diagram of conventional serial communication, and FIG. 7 is a vertical diagram disclosed in Japanese Patent Laid-Open No. 4-336878. It is a block diagram which shows the structure of a synchronous signal mixing communication apparatus.

A conventional serial communication device will be described below. In FIG. 5, 31 is a start signal generating circuit for generating a start signal, 32 is a data transfer circuit for transferring data, 33 is a stop signal generating circuit for generating a stop signal, and 34 is controlled by a serial signal. Reference numeral 35 denotes a controlled circuit to be controlled, and 35 is a serial data transfer request signal for requesting transfer of a serial signal.

FIG. 6 shows a serial data transfer request signal 35.
And the start signal output from the start signal generation circuit 31, the data, the stop signal output from the stop signal generation circuit 33, and the synchronization signal in terms of time, that is, the timing.

The operation of the conventional serial communication device configured as described above will be described below. The start signal generation circuit 31 is activated by the serial data transfer request signal 35, then the data transfer circuit 32 is activated by the end signal of the start signal generation circuit 31, and then
The stop signal generation circuit 33 is activated by the end signal of the data transfer circuit 32, and as shown in FIG. 6, a start signal, data, and a stop signal are continuously generated regardless of the synchronization signal.

The vertical synchronizing signal mixing communication device disclosed in Japanese Patent Laid-Open No. 4-336878 will be described below. In FIG. 7, 61 is a vertical synchronizing signal source, and 62 and 63
Is a microprocessor, 64 is a vertical synchronization mixing circuit, 65
Is a vertical sync separation circuit.

The vertical synchronizing signal from the vertical synchronizing signal source 61 is connected to the interrupt signal input terminal 68 of the microprocessor 62, and the transmission signal output from the asynchronous serial communication transmitting terminal 69 of the microprocessor 62 is vertical with the vertical synchronizing signal. The signals are input to the sync signal mixing circuit 64 and mixed.

The asynchronous serial communication transmission terminal 71 of the microprocessor 63 is connected to the asynchronous serial communication reception terminal 70 of the microprocessor 62 through the communication path 67.

The transmission signal in which the vertical synchronization signal is mixed is connected to the vertical synchronization separation circuit 65 through the communication path 66, and the vertical synchronization signal and the transmission signal separated and output by the vertical synchronization separation circuit 65 are respectively microprocessors. 63, an interrupt signal input terminal 73 and an asynchronous serial communication receiving terminal 72
Is input to

The operation of the vertical synchronizing signal mixing communication device thus configured will be described below. First, the data takes one of the values "1" corresponding to the presence of communication data and "0" corresponding to the absence of communication data, and two consecutive data have a period equal to or longer than the stop bit period ".
By taking advantage of the characteristic that it does not become "0 (space)", the vertical synchronizing signal is multiplexed with the serial signal by setting the vertical synchronizing signal to "0" for a period longer than the stop bit period in two consecutive data. The processing is performed in synchronization with the vertical synchronization signal.

[0013]

However, in the above-described conventional serial communication apparatus, when serial communication is performed, data changes regardless of the sync signal of the television, so that interference or noise can be seen on the screen. In addition, since the data transfer rate during serial communication is constant, there is a problem that a large amount of data cannot be transmitted during the synchronization signal under that condition.

In the case of the vertical synchronizing signal mixed communication device disclosed in Japanese Patent Laid-Open No. 4-336878, the controlled circuit can be controlled in synchronization with the vertical synchronizing signal. There was also a problem that data could not be sent during the period.

The present invention solves the above problems and allows a large amount of data to be changed in a circuit controlled by a serial signal during the period of a synchronizing signal, which causes interference and noise on the screen. An object of the present invention is to provide a serial communication device capable of preventing occurrence and improving image quality.

[0016]

In order to achieve the above object, a serial communication device of the present invention is a serial communication device for controlling a controlled circuit by a serial signal composed of a start signal, data and a stop signal. A start signal generating circuit for generating the start signal based on a serial data transfer request signal for requesting transfer of the serial signal to a controlled circuit; and detecting the end point of the start signal to detect the data. And a stop signal generation circuit that generates the stop signal in synchronization with the synchronization signal after the transmission of the data is completed.

[0017]

According to the above construction, the start signal of the serial signal is transmitted by the start signal generation circuit, and the data of the serial signal is transmitted by the data transmission circuit asynchronously with respect to the synchronization signal. The stop signal generation circuit transmits the stop signal of the serial signals in synchronization with the synchronization signal.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A serial communication device according to an embodiment of the present invention will be described below with reference to the drawings.

A first embodiment of the present invention will be described. FIG. 1 is a block diagram showing a serial communication device of a first embodiment of the present invention, and FIG. 4 is a timing diagram of the first embodiment of the present invention.

In FIG. 1, 1 is a start signal generating circuit for generating a start signal, 2 is a data transmitting circuit for transmitting data, 3 is a stop signal generating circuit for generating a stop signal, and 4 is a serial signal. A controlled circuit controlled by a signal, 5 is a serial data transfer request signal for requesting transfer of a serial signal, and 6
Is a television sync signal.

The operation of the serial communication device configured as described above will be described below. The start signal generation circuit 1 is activated by the serial data transfer request signal 5, the data transmission circuit 2 is activated by the end signal of the start signal generation circuit 1, and the synchronization after the transmission end signal of the data transmission circuit 2 is received. The stop signal generation circuit 3 is activated by the signal. As shown in the timing chart of FIG. 4, since only the stop signal is transmitted in synchronization with the synchronization signal, it is possible to transmit only the stop signal even if the synchronization period is short.

A second embodiment of the present invention will be described. FIG. 2 is a block diagram showing a serial communication device according to the second embodiment of the present invention. In FIG. 2, 11 is a start signal generating circuit for generating a start signal, 12 is a data transmitting circuit for transmitting data, 13 is a stop signal generating circuit for generating a stop signal, and 14 is controlled by a serial signal. 15 is a serial data transfer request signal for requesting transfer of a serial signal, 16 is a television sync signal, and 17 is data to be sent in synchronization with the sync signal. A data determination circuit for determination, 18 is a stop signal generation circuit 1
3 is a synchronous drive switching circuit that switches whether to activate 3 by a data end signal or a synchronization signal.

The operation of the serial communication device configured as described above will be described below. The data determination circuit 17 determines whether the data does not need to be transmitted in synchronization with the synchronization signal or the data that needs to be transmitted in synchronization with the synchronization signal.
When it is necessary to switch the synchronous drive switching circuit 18 so as to drive the stop signal generating circuit 13 by a data transfer end signal as in the conventional serial data transfer device and to send in synchronization with the synchronous signal, the synchronous signal The synchronous drive switching circuit 18 is switched by 16 so as to drive the stop signal generating circuit 13.

With this configuration, since it is possible to generate a stop signal immediately after data transmission for data that does not need to be transmitted in synchronization with the synchronization signal, the data can be transmitted immediately without depending on the synchronization signal.

A third embodiment of the present invention will be described. FIG. 3 is a block diagram showing a serial communication device according to a third embodiment of the present invention. In FIG. 3, reference numeral 21 is a start signal generation circuit for generating a start signal, 22 is a data transmission circuit for transmitting data, 23 is a stop signal generation circuit for generating a stop signal, and 24 is controlled by a serial signal. 25 is a controlled circuit to be controlled, 25 is a serial data transfer request signal for requesting transfer of a serial signal, 26 is a synchronizing signal of the television, and 27 is a signal until the stop signal generating circuit 23 generates a stop signal. , A transfer request control circuit for switching so as not to accept the next serial data transfer request.

The operation of the serial communication device configured as described above will be described below. Since the serial data transfer request comes asynchronously with the synchronous signal, the transfer request control circuit 27 is used even if there is a next serial data transfer request before the stop signal of the serial signal is generated by the previous serial data transfer request. Therefore, the request is not generated, and the serial data transfer can be normally performed even if the interval of the serial data transfer request is shorter than the interval of the synchronization signal.

Although only the sync signal is described in this embodiment, in the case of a television, the vertical sync signal or the horizontal sync signal is usually the sync signal. Further, although only one controlled circuit is specified in this embodiment, there may be a plurality of controlled circuits.

Further, by combining the second and third embodiments, the data which may not be synchronized with the synchronizing signal is transmitted by the conventional method,
A transfer request control circuit may be provided so that data that must be synchronized can be transmitted as soon as possible.

[0029]

As described above, according to the present invention, the start signal of the serial signal is generated by the start signal generating circuit.
The data transmission circuit transmits data of the serial signal asynchronously with respect to the synchronization signal respectively, and then
The stop signal of the serial signal can be transmitted by the stop signal generation circuit in synchronization with the synchronization signal.

Therefore, a large number of data can be changed in the circuit controlled by the serial signal during the period of the synchronizing signal. As a result, in the NTSC system, the vertical synchronizing signal period normally has a time of about 1 millisecond, and when the transfer speed of serial data requires about 10 microseconds for transferring 1 bit, only about 100 bits of the vertical synchronizing signal are required. It is possible to solve the problem that the data cannot be transferred during the period, and it is possible to change the data of a huge amount of information that controls the digitized circuit in recent years during the vertical synchronizing signal period.

As a result, it is possible to improve the image quality by preventing the occurrence of interference or noise appearing on the screen when the data changes.

[Brief description of drawings]

FIG. 1 is a block diagram of a serial communication device according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a serial communication device according to a second embodiment of the present invention.

FIG. 3 is a block diagram of a serial communication device according to a third embodiment of the present invention.

FIG. 4 is a timing diagram of the serial communication device according to the first embodiment of the present invention.

FIG. 5 is a block diagram of a conventional serial communication device.

FIG. 6 is a timing diagram of the serial communication device of the conventional example.

FIG. 7 is a block diagram of another conventional serial communication device.

[Explanation of symbols]

 1, 11 and 21 Start signal generation circuit 2, 12, 22 Data transmission circuit 3, 13, 23 Stop signal generation circuit 17 Data determination circuit 18 Synchronous drive switching circuit 27 Transfer request control circuit

Claims (3)

[Claims] 1. A serial data transfer for requesting a transfer of the serial signal to a controlled circuit in a serial communication device for controlling the controlled circuit by a serial signal composed of a start signal, data and a stop signal. A start signal generation circuit that generates the start signal based on a request signal, a data transmission circuit that detects the end point of the start signal and transmits the data, and a synchronization signal after the transmission of the data is synchronized. And a stop signal generation circuit that generates the stop signal. 2. A data determination circuit that determines whether data is transmitted from a data transmission circuit in synchronization with a synchronization signal or asynchronously, and based on the determination of the data determination circuit,
And a synchronous drive switching circuit for switching the generation of the stop signal by the stop signal generation circuit between synchronous drive and asynchronous drive. 2. When it is determined that data is transmitted in synchronization with a signal, the stop signal is generated in synchronization with the synchronization signal switched by the synchronous drive switching circuit based on the determination. Serial communication device according to. 3. A transfer request control circuit for controlling the input of a serial data transfer request signal to a start signal generation circuit, wherein the transfer request control circuit detects the generation of a stop signal by the stop signal generation circuit, The serial communication device according to claim 1 or 2, wherein a serial data transfer request signal is input to the start signal generation circuit.