JP2655889B2 - Lamp display method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a device such as a printer or a word processor which is program-controlled by a central processing unit (hereinafter referred to as a CPU). The present invention relates to a method of displaying a lamp using a lamp such as an LED.

(Prior Art) FIG. 2 is a configuration diagram of a lamp display device for explaining an example of a conventional lamp display method.

This lamp display device is provided in a device having an operation panel, such as a printer or a word processor. The device includes a microcomputer 1, a functional circuit 2 is connected to the microcomputer 1, and an operation panel 10 is connected via an extended input / output port (hereinafter, referred to as an I / O port) 3. The microcomputer 1 performs program control of the functional circuit 2 and the operation panel 10. The microcomputer 1 controls the entire operation, a read-only memory (hereinafter referred to as ROM) storing programs, and a memory (hereinafter referred to as ROM) for storing data. , RAM), and I / O ports. When the device is, for example, a printer, the functional circuit 2 includes a circuit of a printer mechanism such as a motor and a print head. The operation panel 10 controls the device from the outside and displays the operation state of the device. The operation panel 10 includes a key switch 11 for setting an operation mode and the like, an LED 12 for displaying the state of the device, and an L.
It has a driver 13 for ED drive and the like. These switches 11, LED 12, driver 13, and microcomputer 1
Thus, a lamp display device is configured.

FIG. 3 is a flowchart showing the lamp display method shown in FIG. 2. If there is no high-priority processing such as the printing processing by the functional circuit 2 in the real-time processing, the microcomputer 1 LED1 corresponding to the pressed state of
A background process with a low priority, ie, a lighting state setting process of 2, is performed. That is, the CPU in the microcomputer 1
Reads the background processing program from the program stored in the ROM (step 20), detects the pressed state of the key switch 11 according to the background processing program (step 21), and checks whether the key switch 11 has been pressed. It is determined whether or not the pressed state has changed (step 22). Without pressing the key switch 11,
Key switch sense processing 21 when there is no change in the pressed state
Return to When the key switch 11 is pressed or the pressed state is changed, the CPU sets the lighting state of the LED 12 corresponding to the pressed state (step 23), outputs a control signal for LED display (step 24), and expands. The display state corresponding to the key switch 11 is set by controlling the lighting state of the LED 12 via the I / O port 3 and the driver 13. After this setting, the process returns to the sensing process 21 of the key switch 11.

As described above, in the conventional lamp display method, the change in the state of the device set externally using the key switch 11 is
It was detected by the background processing by the CPU, and the lighting state of the LED 12 was reset only when there was a change.

(Problems to be Solved by the Invention) However, the conventional lamp display method has the following problems.

For example, external I / O port 3 due to external noise such as static electricity
Malfunctions, the output level of the LED drive driver 13 changes, and the LED 12 may enter an erroneous display state. In such a case, if the expansion I / O port 3 is not reset by the key switch 11 or the microcomputer 1 is reset by turning on / off the power switch, the display returns to the normal display state. I can't let it. However, when the key switch 11 is pressed to perform resetting, when an operation error occurs and the microcomputer 1 executes another process, or when the power switch is turned on and off to reset, the microcomputer 1 Not only may the contents of the RAM be erased, causing an operational failure of the functional circuit 2 or the like, but also the recovery process requires time and effort, and it is difficult to solve them.

The present invention has solved the problem of the prior art that the lamp must be reset or reset in order to recover the erroneous lamp display, not only is the recovery operation troublesome, but also causes adverse effects such as operation errors. A lamp display method is provided.

(Means for Solving the Problems) According to the present invention, there is provided a lamp display method for displaying, with a lamp, a state of a device programmed by a one-chip microcomputer having an internal register. A detection process for detecting the state of the device by a microcomputer, a storage process for storing a detection result of the detection process in an internal register of the one-chip microcomputer, and a lamp drive based on the detection result stored in the internal register. Means for turning on / off the lamp with a pulse signal having a predetermined time width.
A setting process for setting the light to be turned off, wherein the detection process, the storage process, and the setting process are repeatedly performed at a predetermined cycle.

(Operation) According to the present invention, the lamp lighting state is reset at a predetermined cycle by repeatedly performing the detection processing, the storage processing, and the setting processing at a predetermined cycle. The lamp driving means turns on the lamp with a pulse signal. By setting the time width of the pulse signal to be small, the lamp flicker at the time of resetting is apparently eliminated. As a result, the erroneous display of the lamp automatically returns to the normal display state without any apparent discomfort. Therefore, the above problem can be solved.

Embodiment FIG. 1 is a configuration diagram of a lamp display device for explaining a lamp display method according to an embodiment of the present invention.

This lamp display device is provided in a device having an operation panel, such as a printer or a word processor. The device includes a microcomputer 30, to which a functional circuit 33 and an operation panel 40 are connected.

The microcomputer 30 program-controls the functional circuit 33 and the operation panel 40. For example, a one-chip (one-chip) 8-bit 8051 microcomputer (manufactured by Intel Corporation, Oki Electric Industry Co., Ltd.) is used. this
The 8051 microcomputer has a special function register SBUF (Serial Port Buffer Register) in which a parallel processing operation circuit and transmission data and reception data are stored in one chip.
And other registers, program ROM, data RAM, timer counter, I / O port, I / O diffusion mode, etc. The serial interfaces RXD and TXD, an interrupt input terminal whose priority can be set, an oscillation circuit having oscillation terminals XTAL1 and XTAL2, and power supply terminals Vcc and Vss are integrated. Then, for example, with the transducer 31 of quartz or the like which is oscillated at a frequency 12MH _Z is connected to the oscillation terminals XTAL1, XTAL2, power supply terminal Vcc, the Vss is connected to a capacitor 33 for charging.

When the device is, for example, a printer, the functional circuit 33 is configured by a circuit of a printer function unit such as a motor and a print head.

The operation panel 40 controls the device from the outside and displays the operation state of the device. The operation panel 40 includes a plurality of key switches 41 for setting an operation mode, a shift register 42 for serial / parallel conversion, and an inverter. 8 LEDs
A drive driver 43, eight LEDs 44, eight overcurrent prevention resistors 45, and the like are provided. As the shift register 42, for example, a 74LS164 integrated circuit (manufactured by Mitsubishi Electric Corporation) is used. This circuit has a serial data input terminal D, a clock input terminal T, output terminals Q0 to Q7, and the like, and is composed of eight edge-triggered D-type flip-flops. The data input terminal D and the clock input terminal T are connected to the serial interfaces RXD and TXD of the microcomputer 20, respectively.
To Q7 are connected to a power supply voltage (for example, +5 V) via a driver 43, an LED 44, and a resistor 45. The key switch 41, the shift register 42, the LED 44, the microcomputer 30 and the like constitute a lamp display device, and the shift register 42 and the driver 43 constitute a lamp driving means.

FIGS. 4 (1) and (2) are flowchart examples of a program for controlling the apparatus of FIG. 1, and FIG. 5 is a flowchart of the apparatus of FIG. 1 in the flowcharts of FIGS. 4 (1) and (2). FIG. 6 is a time chart in the case where control is performed by a program, and the lamp display method of FIG. 1 will be described with reference to these drawings.

First, in the apparatus shown in FIG.
It is assumed that 30 is in the background processing state according to the program stored in the program ROM as shown in FIG. 4 (1) (step 50). At this time, if an interruption such as reception or printing to the functional circuit 33 occurs, it is prioritized and interrupt processing (not shown) is executed at any time. After the interrupt processing is completed, the control returns to the background processing (step 50). Shall be returned. In this background processing (step 50), the microcomputer 30 of FIG. 1 periodically senses (detects) the key switch 41 of the operation panel 40 via the I / O port (step 51), and After the data of the lighting state of the LED 44 is set in a register in the microcomputer in accordance with the pressed state of 41 (step 52), the output to the LED 44 is executed (step 53).

In the LED display output process (step 53), the serial mode of the microcomputer 30 is first set to mode 0 by using the serial interfaces RXD and TXD of the microcomputer 30 as shown in FIG. Steps
53-1), set to I / O expansion mode. As a result, in synchronization with the clock CK output from the serial interface TXD, input and output of 8-bit data D (= D0 to D7) can be performed via the serial interface RXD. Therefore, the data of the LED lighting state set in the previous step 52 is stored in the special function register in the microcomputer 30.
By writing to SBUF (step 53-2), the LED display output is output from the serial interface RXD in the form of serial data D (= D0 to D7) shown in FIG. At the same time, the serial interface TXD
The synchronization clock CK shown in the figure is output.

This clock CK is to be fixed to the half of the frequency 12MH _Z of the basic clock of the microcomputer 30 by the vibrator _{21, 12MH Z × 1/2} = 1MH period of _Z ∴1Myusec clock CK serial interface TXD Output from This background processing (step 50)
In this case, the key switch sensing process (step 51) and the LED display output process (step 51) are performed once every 30 msec on average, including the case where an interrupt process for the functional circuit 33 occurs.
If step 3) is executed, as shown in FIG.
For each c, the serial data D is stored in the shift register 42 on the first floor.
(= D0 to D7) are re-input and converted into parallel data by the shift register 42, and then the output terminals Q0 to Q7
With the output of (1), the lighting state of the LED 44 is reset in a mode corresponding to the key switch 41 (step 54). Its LED44
As shown in FIG. 5, the time required for lighting is about 8 μsec with respect to the state that can be expressed by 8 bits.

 This embodiment has the following advantages.

Due to external noise such as AC noise and electrostatic noise,
The output state of the LED driving driver 43 shown in FIG.
If the lighting status of the ED44 becomes erroneous, LED4
The lighting state of 4 is reset, and LED44 at the time of resetting
The flicker is also about 8 μsec, which is in units of several μsec, and it is almost impossible to visually recognize the flicker.
Therefore, automatically and without any apparent discomfort, without having to reset the LED43 by acquisition as in the past,
The LED 44 can be returned from an erroneous display state to a normal display state. Therefore, it is possible to appropriately prevent adverse effects such as an operation error that occurs at the time of resetting the LED due to a conventional acquisition and an operation failure of the functional circuit 30.

Note that the present invention is not limited to the illustrated embodiment, and various modifications are possible. For example, there are the following modifications.

(A) Although the microcomputer 30 uses the 8051 and the shift register 42 uses the 74LS164, these may be constituted by other 8-bit or 16-bit microcomputers and shift registers.

(B) The driver 43 may be constituted by another circuit such as a buffer other than the inverter, and the LED 44 may be replaced by another lamp such as a miniature bulb or electroluminescence (EL).

(C) The LED 44 is driven by using the shift register 42. If the I / O port of the microcomputer 30 has room, the serial register 42 is omitted and the LED 44 is directly connected to the I / O port of the microcomputer 30. Alternatively, a configuration may be employed in which a plurality of LEDs 44 are connected via an extended I / O port and driven in parallel.

(D) In FIG. 1, when a malfunction occurs in the logic circuit in the functional circuit 33 due to external noise or the like, the malfunction can be prevented by applying the flowchart of FIG.

(Effects of the Invention) As described in detail above, according to the present invention, the device state is detected and stored in the internal register, and the setting of the lamp display state is repeatedly performed at a predetermined cycle based on the stored detection result. Thus, even if the output of the lamp driving means changes due to external noise or the like and the lamp lighting state is erroneously displayed, the lighting state of the lamp can be reset at a predetermined cycle, and the time width of the pulse signal is further reduced. As a result, the lamp flicker at the time of resetting can also be made invisible. Therefore, the lamp can be returned from the erroneous display state to the normal display state automatically and without any apparent discomfort without resetting the lamp by obtaining the lamp as in the conventional case. It is possible to accurately prevent adverse effects such as an operation error at the time of resetting and an operation failure of another circuit.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a lamp display device for explaining a lamp display method showing an embodiment of the present invention, FIG. 2 is a configuration diagram of a lamp display device for explaining a conventional lamp display method,
FIG. 3 is a flowchart of FIG. 2, and FIG.
(2) is a flowchart of FIG. 1, and FIG. 5 is a time chart of FIG. 30 …… Microcomputer, 33 …… Functional circuit, 40 ……
Operation panel, 41: Key switch, 42: Shift register, 43: Driver, 44: LED.

Claims (1)

(57) [Claims] 1. A lamp display method for displaying, with a lamp, a state of a device program-controlled by a one-chip microcomputer having an internal register, a detection process of detecting the state of the device by the one-chip microcomputer; A storage process of storing a detection result of the detection process in an internal register of the one-chip microcomputer; A lamp display method, comprising: a setting process for setting light-off, wherein the detection process, the storage process, and the setting process are repeatedly performed at a predetermined cycle.