JPS61157131A - Synchronizing serial interface - Google Patents

Abstract

PURPOSE:To use software change for expansion and to connect one transmission/reception means and lots of transmission/reception means by assigning a bit identifying information destination and sender to a format. CONSTITUTION:Figure shows a signal format representing the assignment of a serial input signal 1 and a serial output signal 2 in the unit of bits. A caption 4 indicates a signal format of a serial output signal and a caption 5 shows a signal format of a serial input signal and the bit assignment of the same form is attained. A bit C/D in the serial output signal 4 is a bit identifying whether a 8-bit frame is a command signal or a data signal, bits ID2, ID1 and ID0 (in total 3 bits) indicate bits forming ID codes of a destination together with the bit C/D, and lots of units are connected to one set of serial interface by transmitting/receiving a command signal. Since the ID code has 3-bit in this system, the data is transmitted to 8 units.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a signal format of a serial interface between multiple CPUs and internal panels of equipment.

It is particularly suitable for use in mobile terminal devices and other portable devices.

〔overview〕

The present invention provides a synchronous serial interface that processes serial information stored in a format with configurable bits, by assigning bits to the format that can identify the destination and the source of the information. This allows connection to a large number of transmitting and receiving means, and expansion can be done by changing the software.

[Conventional technology]

In order to reduce the number of connection interfaces in mobile devices, serialization of signal lines is progressing, and the use of synchronous serial interfaces capable of high-speed transfer, such as those installed in 72 Chimp CPUs, provides hardware advantages. In addition, it is known that there are advantages to software.

[Problem that the invention seeks to solve]

However, this conventional interface, which has a remarkable advantage in the case of one-to-one connection, also has a remarkable advantage in the case of one-to-many connection.
Having a C5 wire for each eliminates the hardware advantage, and 110! to create a C8 wire! Il
! j! is also required, so it is not practical in the case of five or more connections. Also, as a serial interface, R
There are asynchronous interfaces such as S-232C, and some have recently appeared that are installed in CPUs, but this interface has the drawback that it is almost impossible to connect multiple units to one set of signal lines. The present invention solves these drawbacks by providing a signal format that enables one-to-many connections, thereby inheriting the original hardware and software advantages of the serial interface, and furthermore, allowing its expansion by simply changing the software. The purpose is to provide a synchronous serial interface that supports

[Means for solving problems]

The present invention is a synchronous serial interface that is inserted on a path between one transmitting/receiving means and a plurality of transmitting/receiving means, and has means for processing serial information allocated in a predetermined format that passes through this path. As a means for solving the above-mentioned problems, the format is characterized in that it always includes bits that identify the destination and the source of the information.

[Effect]

The 8-bit serial data input and serial data output are controlled by a serial clock. For this 8-bit data, a signal format is used in which identification information as to whether it is a command frame or a data frame, ID number information indicating the sending/receiving partner, information indicating the content of the command or the content of the data is assigned, and as a group of commands. Inquiry about the presence of a transmission request, permission to start transmission, forced stop of transmission, request for retransmission, request to send parity data, inquiry about busy/ready of the destination, request to send the type of device connected to the unit with ID number, start of transmission By having notifications, transmission completion notifications, etc., it is possible to make one-to-many connections to a set of serial interfaces, and it is also possible to send and receive data using the time shring method by adding an ID number to every frame of 8-bit data. Make it.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS A device according to an embodiment of the present invention will be explained below based on the drawings.

FIG. 1 is a waveform diagram showing the operation of a synchronous serial interface to which the signal format of the present invention is applied. In the figure, numeral 1 is a serial output signal, numeral 2 is a serial input signal, and numeral 3 is a serial clock signal.
Consists of bits. The serial output signal 1 and the serial human input signal 2 are outputted at the falling edge of the serial clock signal 3, and are transmitted and received at a timing such that they are sampled and read at the rising edge. Normally, this serial interface is managed by the CPU and is automatically sent out according to program instructions, and when received, the CPU
will be notified.

Next, FIG. 2 is a diagram showing an example signal format showing the bit-by-bit allocation of the serial input signal 1 and the serial output signal 2. In the figure, reference numeral 4 indicates the signal format of the serial output signal, and reference numeral 5 indicates the signal format of the serial input signal, both of which are assigned bits in the same format. In serial output signal 4, bit C/D indicates a bit that identifies whether this 8-bit frame is a command signal or a data signal, and bits ID2 and ID
The three bits I and IDO indicate the bits that form the ID code that indicates the destination of the transmission, and together with the bit C/D, specify the destination, and by sending and receiving command signals, many units can be connected to a set of serial interfaces. to enable data transmission. In this embodiment, since the ID code has 3 bits, data can be transmitted to 8 units. Bits D3, D2, Dl and DO indicate the contents of the command if the C/D bit is a command;
If the D focus is data, the content of the data is shown. Exactly the same allocation as for serial output signal 4 is performed for serial input signal 5 as well.

Since an ID code is added to all transmitted data, other units will not receive this data even if a seal is connected.

Figure 3 shows a command group that can be used in the signal format used in this embodiment.
Bits D3, D2, Dl, DO when the bits are commands
A maximum of 16 types of command groups can be constructed using the 4 bits (hereinafter referred to as command codes). In addition,
The command group shown in FIG. 3 shows the case where a one-to-many connection is made as shown in FIG. 4, and is used between the master unit 6 and the slave unit group 7. Next, this command code will be explained as follows: a. Command code "oooo" This command code is sent from the master side, which means an inquiry to the slave side about whether or not to send it. If there is transmission data on the slave side, a command code "0000" is sent to the master side indicating that there is a transmission request.

If there is no transmission data, nothing is sent, so the master side makes a similar inquiry to the slave of the next ID code.

b. Command code "0001" When this command code is requested to be transmitted from the slave side, it is sent from the master side as a transmission permission for the slave side. This command code is sent from the slave side to notify the master side of the start of transmission.

C. Command code "0010" This command code is sent when the master side wants to forcibly stop transmission on the slave side for some reason while receiving data from the slave side. This command code is sent from the slave side to notify the master side of the stop or end of data transmission.

d. Command code “0011” When the master side wants to retransmit data for some reason while receiving data from the slave side, this command code is sent to request retransmission of data from the slave side. Ru.

e. Command code "0100" This command is sent on the master side while receiving data from the slave side, causing parity data to be sent from the slave side and checking whether the data received so far is correct. When this command code is received on the slave side, the parity data calculated based on the data sent so far is sent to the master side.

d. Command code "01101" This command code is sent when the serial interface on the slave side is initialized by the master side during a series of initialization processes such as when the power is turned on. When this command code is received on the slave side, all flags, Ilo, etc. related to the serial interface are returned to their initial states.

f. Command need "0111" When data is transmitted from the master side to the slave side, this command code is sent, and an inquiry is made as to whether the slave side can receive data. When this command code is received on the slave side, if it is receivable, the command code is sent out and the master side is notified that it can be received. Also, when it is not possible to receive anything, nothing is sent.

g. Command code "1000" After the slave side is initialized from the master side, this command inquires about the type of equipment connected to the slave side. In this embodiment shown in FIG. 4, eight slave units are connected at the same time.
This command allows connection of 16 different devices to one connection point. When the slave side receives this command code, it sends the type of connected device to the master side and notifies it.

h. Command code “1001” This is a command code that notifies the start of data transmission from the master side to the slave side. This command code is sent when the slave side is ready to receive, and when it becomes ready to receive, it does not send anything, thereby notifying the master side that it is busy.

i. Command code "1010" This is a command code that notifies the slave side of the end of data transmission while data is being sent from the master side to the slave side.

A serial interface is configured by applying the command group described above.

Next, the operation of transmitting data from the master side to the slave side in the one-to-many connected embodiment device using the command group described in FIG. 3 will be explained based on FIG. 5.

A command code "1001" is sent from the master side to the slave side, and the master side notifies the slave side of a data transmission request (sl).

Next, the command code "1001" is received on the slave side, and since it is ready to receive, the command code "1001" is returned.
is sent to the master side and is notified of the receivable state (S
2). When the command code "1001" is received on the master side, it is recognized that the slave side can receive data, and data transmission is performed in sequence (S3 and S4). When the data transmission from the master side is completed, the command code is “0”.
100'' is sent, and a parity 11 output request is made to check whether the transmitted data has been correctly received on the slave side 1 (S5).The slave side issues a command code ``100''.
0100" is received and the parity data of the received data is sent to the master side (S6). The master side receives this, compares the parity data, and if it is correct, sends the command code "1010" to the slave side. The end of data transmission from the master side to the slave side is notified (S7).

In this way, data transmission from the master side to the slave side is completed, but all frames of transmitted and received data are
Since the D code is added, other slaves will not recognize this data as their own data. Additionally, the master side can time-divide data to multiple slave sides.

〔Effect of the invention〕

As explained above, by using the serial interface to which the signal format according to the present invention is applied,
- A plurality of units can be connected to a set of interface lines, and expansions and unit replacements can be handled simply by changing the software.

[Brief explanation of drawings]

FIG. 1 is a waveform diagram showing the operation of a synchronous serial interface. FIG. 2 is a format diagram showing the bit correspondence of signal format I. FIG. 3 is a list diagram showing command groups related to signal formats. FIG. 4 is a block diagram showing a circuit according to an embodiment of the present invention. FIG. 5 is a signal sequence diagram showing the operation of the circuit according to the embodiment of the present invention. 1... Serial output signal, 2... Serial input signal, 3... Serial clock signal, 4... Signal format of serial output signal, 5... Signal format of serial human input signal, 6... Master side unit, 7
...Slave side unit.

Claims (1)

[Claims] (1) In a synchronous serial interface that is inserted on a path between one transmitting/receiving means and a plurality of transmitting/receiving means, and has means for processing serial information allocated in a predetermined format that passes through this path, A synchronous serial interface characterized in that the format always includes bits that identify a destination and a source of information.