JPH05241995A - Serial data transmission method - Google Patents

Abstract

PURPOSE:To accelerate transmission speed by reducing data quantity when a data group comprised of plural bytes is transmitted by performing transmission by changing the parity mode of only a leading byte in plural bytes. CONSTITUTION:Assuming that the serial transmission formats of a serial transmission part 7 and reception equipment 8 are set by eight bits and are used in a mode of even parity, a central processing unit 6 sets a mode at the one of odd parity only when a data format shows the one of first byte before the serial transmission part 7 performs the data transmission of the first byte. The reception equipment 8 judges a received first byte as a parity error. When the first byte in which the parity error occurs is received, the reception equipment 8 side judges a signal to be transmitted as the position signal of the input panel 2 of a digitizer 1. The serial transmission part 7 returns the mode to an original mode of even parity before a second byte is transmitted successively, and furthermore, transmits second byte data and third and fourth byte data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The purpose of this invention is to reduce the transmission time in a computer device that transmits byte data continuously a plurality of times when transmitting and receiving data serially.

[0002]

2. Description of the Related Art Conventionally, when serially outputting coordinate data serially from an input device that transmits data composed of a plurality of bytes, for example, a digitizer, the output data is X
Coordinates, Y coordinates, and pen status information are composed of multiple bytes. As an example, when the X coordinate 1200, the Y coordinate 2305, and the pen up / down state are 1, the data format is as shown in FIG.
As shown in (a), a 12-byte character string is composed of ASCII code character strings, and a CR code is added as an end code to determine the end of reception of one component data, or to reduce the transfer amount. As in 4 (b), 1 with 5 bytes
The hexadecimal code is transmitted in a binary data format so that the first byte data and the coordinate data section can be distinguished from each other.

[0003]

According to the above-mentioned conventional technique, when a curve is traced on a digitizer and input, if the coordinate data transmission speed is slower than the pen movement speed, accurate input is not possible. Since it may not be possible, it is necessary to improve the data transmission speed, and as a means to increase it, it is possible to increase the serial transfer speed, but increase the operating speed of both the transmission side and the reception side, and data loss occurs On the contrary, it was necessary to prevent the transfer rate from decreasing with respect to the amount of data. In this case, the cost is increased and the circuit is complicated.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and in a device for serially transmitting one data composed of a plurality of bytes at any time, the head of the plurality of bytes Byte-only parity mode
The present invention proposes a serial data transmission method in which the data is changed and transmitted, and the receiving side recognizes the first byte as a parity error by a parity check, recovers the parity mode of the subsequent data and transmits.

[0005]

According to the transmission method of the present invention, one byte of delimiter data can be omitted and the overall data transmission speed can be improved. Therefore, without improving the hardware performance, the transmission method shown in FIG.
As shown in, the parity bit sent together with 8-bit data is used as the serial transmission format, and the parity error is intentionally generated only when the first byte is serially transmitted, so that the reception side recognizes the first byte by the parity check. The present invention proposes a serial data transmission method characterized by the above.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. First, FIG. 1 is an example of a transmission data format according to the present invention, and FIG. 2 is a block diagram showing a configuration for explaining an embodiment of the present invention. When the input pen 3 is brought into contact with the input plate surface 2, the digitizer 1 receives a signal corresponding to the contacted position, and a coordinate detection unit 4 and an address for calculating the X coordinate and Y coordinate values from this signal. Converter 5,
Further, a central processing unit 6 that receives the calculated address value and performs data processing for serial transmission, and a serial transmission that uses a communication interface such as Intel's 8251 as an interface for actual serial transmission. And part 7.

Therefore, the coordinate detection unit 4 and the address conversion unit 5 calculate values from the position signals detected from the coordinates of the input plate surface 2 and the input pen surface 2 designated by the input pen 3, and the central processing unit 6 calculates the values. 1st as shown in Figure 1
The X coordinate value is converted into a binary data format by the byte and the second byte, and the Y coordinate value is converted by the third byte and the fourth byte. Further, in the fourth byte D7, the state of contact of the input pen 3 with the input board surface 2 is used as a flag. Then, each byte data is sent to the serial transmission unit 7, and the serial transmission unit 7 transmits the serial data to the receiving device 8 in the format shown in FIG.

At this time, if the serial transmission format of the serial transmission unit 7 and the reception device 8 is set to be used in advance in the mode of 8 bits and even parity, the central processing unit 6 uses the first byte shown in FIG. Data format (D0-
Serial transmission unit 7 only when D7 is a binary value of X coordinate
Puts the first byte into odd parity mode before transmitting data. Since the parity mode of the receiving device 8 is set to even parity, the received first byte is determined to be parity error.

When the first byte in which a parity error has occurred is received, the receiving device 8 side determines that the signal to be transmitted is the position signal of the input board surface 2 of the digitizer 1. Before continuously transmitting the second byte, the serial transmission unit 7 returns to the original mode of even parity and transmits the second byte data and further the third and fourth byte data. As a result, on the receiving device 8 side, the byte data in which an error has occurred can be discriminated as the first byte by performing a parity check, and the data will be sent thereafter.
The X and Y coordinate values can be received from the byte data. Here, F of D7 of the 4th byte is a flag of the state of contact of the input pen 3 with the input board surface 2 as in the conventional case.

When the signals from D0 of the first byte to D7 of the fourth byte are received, the input device 8 identifies the position signal by the 4 bytes of the first byte to the fourth byte. When the input pen 3 is used not as a position signal detection but as a function key, for example, a conventional character string signal is transmitted.

[0011]

According to the present invention, the amount of data when transmitting a data group composed of a plurality of bytes can be reduced, and therefore the transmission speed can be increased.

[Brief description of drawings]

FIG. 1 is a transmission data format according to the present invention.

FIG. 2 is a block diagram of a configuration for realizing transmission according to the present invention.

[Figure 3] 1-byte serial transmission format diagram

FIG. 4 Conventional transmission data format

[Explanation of symbols]

 1 digitizer 2 input board surface 3 input pen 4 coordinate detection unit 5 address conversion unit 6 central processing unit 7 serial transmission unit 8 receiving device

Claims (1)

[Claims] 1. A device for serially transmitting one data composed of a plurality of bytes at any time, only the first byte of the plurality of bytes is changed in parity mode and transmitted, and the receiving side transmits the first byte by a parity check. A serial data transmission method characterized by recognizing as a parity error, recovering the parity mode of the subsequent data and transmitting.