JPH10285243A - Serial communication interface device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce power consumption and to make an operation time by means of a battery power source, etc., long by stopping power supply to a second transmitting means when a first mode is set. SOLUTION: A mode setting part 8 recognizes whether an input signal is in a synchronous mode or a start-stop synchronous mode and outputs a mode setting signal Sm to a circuit interruption control part 9. Then, it is judged whether the start-stop synchronous mode is selected or not and turns off a switch 7 in order to stop power supply to a synchronizing receiver/driver 5. Thus, power is supplied only to a start-stop synchronizing receiver/driver 3. When the mode is changed from the start-stop synchronous one to the synchronous one, the switch 7 is turned on so as to supply power to the both start-stop synchronizing receiver/driver 3 and synchronizing receiver/driver 5. Since power is supplied to the synchronizing receiver/driver 5 only when the synchronous mode is set so that power consumption is saved and the operation time of a battery is made to long.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a serial communication interface device.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram showing a configuration of a conventional serial communication interface device. In FIG. 1, reference numeral 1 denotes a system bus to which a plurality of personal computers (not shown) are connected. Reference numeral 2 denotes a serial communication controller connected to the system bus 1, which controls serial communication according to a predetermined communication protocol.

[0003] Reference numeral 3 denotes a start / stop synchronization receiver / driver used for start / stop (asynchronous) serial communication. Receive communication data. Further, the start / stop synchronization receiver / driver 3 transmits start-stop synchronization mode communication data input from a personal computer (not shown) via the serial connector 4 to the system bus 1 via the serial communication controller 2.

[0004] The serial connector 4 is connected to a personal computer (not shown). Reference numeral 5 denotes a synchronization receiver / driver provided in parallel with the start / stop synchronization receiver / driver 3.
This is a driver and is used for serial communication in synchronous mode. The synchronization receiver / driver 5 receives synchronous mode communication data transmitted from a partner personal computer via the system bus 1 and the serial communication controller 2, and receives input from the personal computer via the serial connector 4. The communication data in the synchronous mode is transmitted to the system bus 1 via the serial communication controller 2.

[0005] Reference numeral 6 denotes a power supply which constantly supplies power to the start / stop synchronization receiver / driver 3 and the synchronization receiver / driver 5 via the serial communication controller 2.

[0006]

By the way, in the conventional serial communication interface device, the start / stop synchronization receiver / driver 3 and the synchronization receiver / driver 5 are used.
Are always supplied with power regardless of whether or not they are used. Therefore, in the conventional serial communication interface device, there is a problem that useless power is consumed by the synchronization receiver / driver 5 which is rarely used. In particular, a portable computer driven by a battery (power supply 6) has a drawback that the operation time is shortened by wasteful power consumption by the synchronization receiver / driver 5. The present invention has been made under such a background, and an object of the present invention is to provide a serial communication interface device capable of reducing power consumption and extending operation time by a battery.

[0007]

According to a first aspect of the present invention, there is provided a serial communication interface device for interfacing between a system bus and a computer, the first mode communication being input from the system bus or the computer. To a first transmission unit for transmitting data, a second transmission unit for transmitting communication data in a second mode input from the system bus or the computer, and to the first and second transmission units. A power supply for supplying power, and control means for stopping supply of the power to only the second transmission means when the first mode is set, are provided. According to a second aspect of the present invention, there is provided the serial communication interface device according to the first aspect, wherein the first and second serial communication interfaces are provided.
A mode monitoring means for monitoring which mode is set among the modes, wherein the control means controls the second power means only when the first mode is set by the mode monitoring means. Is stopped. According to a third aspect of the present invention, in the serial communication interface device according to the first or second aspect, the first mode is a start-stop synchronization mode, and the second mode is a synchronization mode. And

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a serial communication interface device according to one embodiment of the present invention. In FIG. 1, portions corresponding to the respective portions in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. FIG.
, A switch 7, a mode setting unit 8 and a line disconnection control unit 9 are newly provided.

The switch 7 is interposed between the serial communication controller 2 and the receiver / driver 5 for synchronization, and turns off / on the supply of power from the power supply 6 to the receiver / driver 5 for synchronization. The mode setting unit 8 sets one of the start-stop synchronization mode and the synchronization mode used in the serial communication interface device based on a signal input from a personal computer (not shown), and a mode setting signal representing the mode. Sm
Is output.

[0010] The circuit disconnection control unit 9 receives the mode setting signal Sm.
, The switch 7 is controlled to be on or off. That is, the circuit disconnection control unit 9 turns on the switch 7 when the mode setting signal Sm indicates the synchronous mode, and turns off the switch 7 when the mode setting signal Sm indicates the start-stop synchronous mode. To

Next, the operation of the serial communication interface device according to the above-described embodiment will be described with reference to the flowchart shown in FIG. When the personal computer is started in step S1 shown in FIG. 2, the personal computer outputs a signal to the mode setting section 8 indicating that either the synchronous mode or the start-stop synchronous mode is set. Now, it is assumed that a signal indicating the start-stop synchronization mode is output from the personal computer.

Thus, in step S2, the mode setting unit 8 confirms whether the signal input from the personal computer indicates the communication mode of the synchronous mode or the start-stop synchronous mode, and then checks the communication mode. Is output to the circuit disconnection control section 9. In this case, after confirming that the communication mode is the start-stop synchronization mode, the mode setting unit 8 outputs the mode setting signal Sm representing the start-stop synchronization mode to the circuit disconnection control unit 9.

In step S3, the circuit disconnection control unit 9
Whether the start-stop synchronization mode is selected or not is determined based on the input mode setting signal Sm. In this case, since the mode setting signal Sm indicates the start-stop synchronization mode, the circuit disconnection control unit 9 determines “YES” in step S3.
To step S4.

In step S4, the circuit disconnection control section 9
The switch 7 is controlled so as to stop supplying power to the receiver / driver 5 for synchronization. That is, the circuit disconnection control unit 9
Turns off the switch 7, and then proceeds to step S6.
Thus, the supply of power from the power supply 6 to the synchronization receiver / driver 5 is stopped, and power is supplied only to the start / stop synchronization receiver / driver 3.

In step S6, assuming that the communication mode has now been changed from the start-stop synchronization mode to the synchronization mode, the mode setting unit 8 outputs a mode setting signal Sm indicating the synchronization mode to the circuit disconnection control unit 9, and Returning to S2, the above-described process is repeated.

In step S2, the circuit disconnection control unit 9
After confirming the currently set communication mode, that is, the synchronous mode, from the input mode setting signal Sm, step S
Proceed to 3.

In step S3, the circuit disconnection control section 9 sets the determination result to "NO" and proceeds to step S5. In step S5, the circuit disconnection control section 9 performs the start / stop synchronization receiver / driver 3 and the synchronization receiver / driver. The switch 7 is controlled so as to supply power to the switch 5 together. That is, the circuit disconnection control unit 9 turns on the switch 7. Thus, the power from the power supply 6 is supplied to both the receiver / driver 5 for synchronization and the receiver / driver 3 for start-stop synchronization.

As described above, according to the serial communication interface device of one embodiment, power is supplied to the synchronization receiver / driver 5 only when the synchronization mode is set, so that power consumption is reduced. Thus, the operation time when the power source 6 is a battery can be lengthened.

[0019]

According to the present invention, when the first mode is set, the supply of power to only the second transmission means is stopped, so that the power consumption is reduced as compared with the conventional one. Can, and in turn, power (eg a battery)
The effect of this is that the operation time can be extended.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a serial communication interface device according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation of the serial communication interface device according to the same embodiment.

FIG. 3 is a block diagram illustrating a configuration of a conventional serial communication interface device.

[Explanation of symbols]

 2 Serial communication controller 3 Start / stop synchronization receiver / driver 4 Serial connector 5 Synchronization receiver / driver 6 Power supply 7 Switch 8 Mode setting unit 9 Circuit disconnection control unit

Claims (3)

[Claims] 1. A serial communication interface device for interfacing between a system bus and a computer, wherein: a first transmission means for transmitting first mode communication data input from the system bus or the computer; A second transmission unit that transmits communication data in a second mode input from a system bus or the computer; a power supply that supplies power to the first and second transmission units; and the first mode is set. Control means for stopping supply of the electric power to only the second transmission means when the communication is performed. 2. A mode monitoring means for monitoring which one of a first mode and a second mode is set, wherein the control means controls the first mode by the mode monitoring means.
2. The serial communication interface device according to claim 1, wherein when a mode is set, supply of power to only the second power unit is stopped. 3. The serial communication interface device according to claim 1, wherein the first mode is a start-stop synchronization mode, and the second mode is a synchronization mode.