JPS63141154A - Keyboard device - Google Patents

Abstract

PURPOSE:To recover a keyboard device to a normal state even when an abnormal operation is generated in the keyboard device, by recovering the keyboard device to an initialized state by hardware-resetting it by the command of a host device. CONSTITUTION:When the keyboard device is placed under a stalled state, the abnormal operation is detected by the host device 10, and a transmission request signal is sent to the keyboard device through a communication line 102. When the transmission request signal is inputted from a branch line 104 to a hardware reset circuit 15, a prescribed hardware reset signal 105 is outputted from the circuit to a keyboard control circuit 11. Thereby, the keyboard control circuit 11 is recovered to the initialized state in a hardwarewise, and the keyboard device can steal out of the stalled state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a keyboard device used for data input/output, etc. of an information processing device.

[Conventional technology]

Generally, an operator operates an information processing device and inputs/outputs data using a keyboard.

When you press a key switch on a keyboard, the information processing device converts the keystrokes into character codes and uses them to proceed with processing. In order to reduce the burden on the information processing device for character encoding processing, keyboard devices in which a microprocessor or the like for performing the encoding processing is incorporated in the key switch are also widely used.

In such a keyboard device, for example, as shown in FIG. 3, a keyboard control circuit 21 is connected to an internal path line 201.
A host device interface circuit 22 is connected to a key input circuit 23, and a key switch 24 is connected to the key input circuit 23.

The keyboard control circuit 21 is a circuit for encoding the manual keystrokes of the key matrix of the key switches 24, and is composed of a microprocessor, a memory storing a program for executing a predetermined process, and the like. The key input circuit 23 is an Ilo control circuit that receives the output signal of the key switch 24 and causes the keyboard control circuit 21 to read it through the internal pass line 201.

The host device interface circuit 22 is a circuit that controls data transmission and reception between the internal path line 201 and the communication line 202. This communication line 202 is connected to a host device (not shown).

With the above configuration, the key force from the key switch 24 is
It is encoded within this keyboard device and sent to the host device.

[Problem that the invention seeks to solve]

Now, in the conventional keyboard device shown in FIG. 3, the keyboard control circuit 21 executes a program that operates independently of the host device, and encodes human input keys by so-called firmware processing.

Therefore, if this firmware processing malfunctions due to the input of some kind of external noise, a so-called processor stall state, in which the processor enters an infinite loop, will occur, and communication with the host device will stop.

The present invention has been made in view of the above points, and an object of the present invention is to provide a keyboard device in which a host device can detect such an abnormality in the keyboard device and promptly restore the keyboard device to a normal state. It is.

[Means for solving problems]

A keyboard device of the present invention includes a key switch, a keyboard control circuit that processes an input signal of the key switch,
A host device interface circuit that controls the transmission and reception of signals between the keyboard control circuit and the host device, and a hardware reset that returns the keyboard device to its initial state when a predetermined reset signal is received from the host device. A hardware reset circuit is also included.

[Effect]

In the above-described keyboard device, when communication with the host device is stopped due to abnormal operation, the host device recognizes this and operates the hardware reset circuit. The hardware reset circuit performs a hardware reset of the keyboard device to return it to an initial state in response to a command from a host device.

This allows the keyboard device to automatically return to normal operation again.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the keyboard device of the present invention.

In this device, a keyboard control circuit 11, a host device interface circuit 12, and a key input circuit 13 are connected to an internal path line 101, a key switch 14 is connected to the key input circuit 13, and a keyboard control circuit 11 is connected to the key input circuit 13. The configuration is such that a hardware reset circuit 15 is connected to.

This device is connected to the host device 10 via a communication line 102. A part of this communication line 102 is branched, and this branch line 104 is connected to a hardware reset circuit 15.

The keyboard control circuit 11 is a circuit that encodes the keystrokes of the key switches 14 and controls communication with the host device 10. This consists of a microprocessor and a memory that stores programs for its operation.

The key switch 14 is a well-known keyboard on which a large number of keys are arranged, and the half-input circuit 13 is a circuit that operates to control the I10.

The host device interface circuit 12 is, for example, a serial interface circuit such as R5-232C for transmitting and receiving signals between the internal path line 101 and the communication line 102. The above points are no different from known keyboard devices.

In addition to this, the keyboard device of the present invention is provided with a hardware reset circuit 15.

The hardware reset circuit 15 is composed of an AND circuit 31, a counter circuit 32, and a NAND circuit 33, as shown in FIG.

This AND circuit 31 is connected to a clock signal line 3 that transmits a control clock signal generated inside the keyboard device.
01 and the communication line 1020 branch line 104 shown in FIG. Further, the counter circuit 32 is a circuit that receives the output of the AND circuit 31, receives the output from the branch line 104 to the SD double signal reset terminal, and outputs the count value 303 to the NAND circuit 33, which will be explained later. . Nand circuit 33
is a circuit that receives the count value 303 output from the counter circuit 32, inverts the AND thereof, and obtains and outputs the hardware reset signal 105.

In the keyboard device configured as described above, the host device 10 (FIG. 1) detects the abnormal operation and sends a transmission request signal (send data signal, hereinafter referred to as the SD double signal) to the keyboard device through the communication line 102. When the SD double signal branch line 104 is input to the hardware reset circuit 15, a predetermined hardware reset signal 105 is outputted from this circuit to the keyboard control circuit 11. As a result, the keyboard control circuit 11 can be returned to its initial state in terms of hardware, and can be removed from the stalled state.

Next, a more specific operation of this device will be explained.

First, on the keyboard device side, in addition to data transmission through operation with the key switch 14, a specific command (instruction) is sent from the keyboard control circuit 11 through the host device interface circuit 12 at a cycle of about 100 m5ec (milliseconds). continues to be sent to the host device 10.

In the host device 10, the command input cycle IQQms
A timer for a sufficiently long time compared to ec, for example 2QQmsec, is provided. Then, when it receives a command, it sets its timer. After that, when a new command is input and the request is recognized, the timer is set again.

Therefore, as long as commands are input at a cycle of 100 m5 ec, a so-called timeout in which the timer counts beyond 200 m5 ec will not occur.

However, when the keyboard device stalls, inputting the command stops and the timer reaches 200m5eC.
timeout exceeds the count. by this,
The host device can detect an abnormality in the keyboard device.

Under normal conditions, the host device 10 sends an interface signal including an SD double signal to the keyboard device through the communication line 102. This SD double signal is at a high level under normal conditions.
This is a signal that alternately and periodically repeats the states of "H" and low level "L".

On the other hand, when the host device 10 detects a timeout of the timer, the SD multiplication signal is set for a certain period of time (for example, 5m5ecc7).
This time is sufficient for the counter circuit 32 shown in FIG. Please select on time.

Now, in FIG. 2, the hardware reset circuit 15
The AND circuit 31 inside receives the SD double signal from the branch line 104 to open and close the gate.

Clock signal 302 input from clock signal line 301
is normally outputted to the counter circuit 32 in accordance with the opening/closing period of the gate. The counter circuit 32 counts up when it receives the clock signal 302, but the SD multiplication signal "H", "L", which is manually input to the reset terminal,
Since it is periodically inverted to "H", it is quickly reset at this cycle. Therefore, even if the count value 303 from the counter circuit 32 is input to the NAND circuit 33 in parallel, the output of the NAND circuit 33 is always held at the "L" level.

Here, the SD multiplication signal higher-level device is used for a certain period of time, for example, 5
When the level is set to “L” above m5ec, the AND circuit 31
The counter 32 counts up the clock signal 3°2 outputted from the counter 32 until it reaches its upper limit, and all the count values reach the "H" level. At this time, the hardware reset signal of "H" level is sent from the NAND circuit 33. 10
5 is output to the keyboard control circuit 11 (FIG. 1). In response to this, the keyboard control circuit 11 forcibly resets its operation using hardware.

Thereafter, the keyboard device starts operating again from the initial state, and normal communication continues.

Note that each block of the circuit in the above embodiments may be replaced with a circuit block having a similar function, and may be freely divided or integrated. Furthermore, the SD double signal may be changed to one with appropriate content so that the same operation can be performed.

〔Effect of the invention〕

According to the keyboard device of the present invention as described above, since a hardware reset circuit is provided that is reset by a command from a host device, even if the keyboard device becomes stalled and input from the operator becomes impossible,
It is possible to automatically restore the abnormal state to a state where it can be continued before the operator notices the abnormal state.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the keyboard device of the present invention, FIG. 2 is a detailed block diagram of its hardware reset circuit, and FIG. 3 is a block diagram showing an example of a conventional keyboard device. 10... Host device, 11... Keyboard control circuit, 12...
- Host device interface circuit, 13... Key input circuit, 14... Key switch, 15... Hardware reset circuit. Applicant: NEC Corporation Representative

Claims (1)

[Claims] A key switch, a keyboard control circuit that processes input signals of the key switch, a host device interface circuit that controls the transmission and reception of signals between the keyboard control circuit and a host device, and a host device interface circuit that receives a predetermined reset signal from the host device. A keyboard device comprising: a hardware reset circuit that, when accepted, executes a hardware reset to return the keyboard device to its initial state.