JPS60180329A - Portable small-sized device - Google Patents

Abstract

PURPOSE:To obtain an interface circuit attaining data transfer between devices having a different power voltage by forming an electronic circuit of a portable small-sized device with a resistor A, a Zener diode and a diode and connecting the three elements in series in an optional order with the anode and cathode of the Zener diode and the diode poled oppositely together. CONSTITUTION:An external connecting terminal 21 consists of a positive power supply and a serial input terminal. A signal inputted from a personal computer through the serial input terminal is converted for the voltage level by an interface circuit 22 and inputted to an electronic circuit 24. The electronic circuit 24 is a one-chip microcomputer, uses a crystal oscillator 23 as a reference signal source and outputs required information onto a liquid crystal display device 27 being a display device by the input from an external operating member 25. The data inputted from the interface circuit 22 is stored in an RAM26 and outputted on the display device a required.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an interface circuit in a small portable device that can input data from an external device.

[Prior art]

Conventional small portable devices that can input data from external devices are often found in computer-related devices, but this is limited to devices with the same power supply voltage, and cannot be used with devices with different power supply voltages. .

〔the purpose〕

An object of the present invention is to provide an interface circuit that enables data transfer between devices with different power supply voltages.

〔overview〕

For small portable devices such as electronic watches, the case is connected to the + side of the power source. The reason is that in the electronic circuit of an electronic watch, the circuit C (integrated circuit) is made of 0MO5, and if multiple power supplies are required, it is convenient to use the + side power supply in common to increase the degree of integration of the circuit O. This is because there is. On the other hand, since a computer uses a grid on one side of its power supply, an interface circuit is required to connect the case of the electronic watch and the ground of the computer and transfer data via another signal line. The present invention provides such an interface circuit, which will be explained in detail below using the drawings.

〔Example〕

As an embodiment of the present invention, FIG. 1 shows the appearance of a data transfer system using the present invention. 11 is Bo'/+/k・
A computer, 12 an electronic clock, and 13 a cable with two signal lines, a ground line and a data line. Data is personal computer 11 Syria A/+
1 interface, such as R3-2320, is connected to an external connection terminal of the electronic timepiece 12 via a data line of a cable 13. Also,
The ground wire is connected to one power source of the personal computer 11 and to the tenth power source of the electronic clock. This system is a system that sends data from a personal computer to a watch.When creating data, it is easy to create and back up data, and it is possible to use a personal computer that can use various peripheral devices. It can be transferred to a highly portable wristwatch.

FIG. 2 is a block diagram of the electronic timepiece shown in FIG. 1. Reference numeral 21 denotes an external connection terminal, which is composed of a power supply and a serial input terminal. A signal input from a personal computer through a serial input terminal undergoes voltage level conversion by an interface circuit (22) and is input to an electronic circuit (24). The electronic circuit 24 is a one-chip microcomputer, and uses the crystal oscillator 23 as a reference signal source and outputs necessary information to a liquid crystal display device 27 as a display device based on input from an external operating member 25. Data input from the interface circuit is stored in 26 RAMs and output to the display device as necessary.

FIG. 6 is a circuit diagram of the interface circuit of FIG. 2. 31 is a ground terminal, and 62 is a serial input terminal. 33 and 35 are resistors of 600Ω, and 36 are resistors of 200Ω. 34 is a Zener diode whose Zener voltage is 5.6 V when the measurement current is 5 mA. 37 is N
PN) Run Sister 38 is a lithium battery with a standard voltage of about 3V and is the power source for the electronic watch. 39 is the output of the interface circuit, which is connected to the electronic circuit. The R1-2520 serial signal from the personal computer is 1,712. V to -5v is logic 1, and +5V to +12V is logic 0. Also, for TTL output, +0.4 V or less is logic 0, -)2.4V
The above is logic 1. To enable input from any of these outputs, set the threshold voltage to +o,
Must be between 4v and +2.4v. As shown in the input/output characteristics of the interface circuit of FIG. 3 in FIG. 4 (this condition is satisfied).

Figure 5 shows an improved version of the interface circuit shown in Figure 3, in which a diode 51 is inserted to interrupt the loop that charges the watch battery when the input becomes R8-2320-112. ing. If the battery is a silver oxide battery, nickel cadmium battery, or capacitor that can be charged without any negative effects, use the interface circuit shown in Figure 3, and if you charge it like a lithium battery, needle-shaped crystals will form inside. The interface circuit shown in FIG. 5 is used for devices that cause an adverse effect such as breaking the separator and causing a short circuit.

〔effect〕

As described above, according to the present invention, it is possible to transfer data between a small portable device that has ten power supplies as the ground, and a device that has one power source as the ground, and also prevents battery deterioration due to charging.
It is possible to prevent electronic circuits from being damaged or malfunctioning due to external static electricity or noise. It has many excellent features, such as when the case of a small portable device is grounded, if a common ground is taken from the case, only one contact is needed for the external connection terminal.

[Brief explanation of drawings]

FIG. 1 shows the appearance of a data transfer system using the present invention. 2 is a block diagram of the electronic timepiece shown in FIG. 1. FIG. 6 is an embodiment of the present invention, and is a circuit diagram of the interface circuit shown in FIG. FIG. 4 shows the input/output characteristics of the circuit shown in FIG. FIG. 5 shows an embodiment of the present invention. Applicant: Suwa Seikosha Co., Ltd. Figure 1 3 Figure 2 r, Figure 13 ε; Figure S4 Figure 5

Claims (2)

[Claims] (1) At least a reference signal source, power supply, and electronic circuit. It consists of a display device, an external operation member, an interface circuit with external equipment, and an external connection terminal, and the interface consists of at least a circuit C in which a resistor A and a Zener diode B are connected in series, and a resistor, One end of the cathode side of the Zener diode is connected to the external connection terminal, one end of the anode side of the circuit C is connected to an electronic circuit and one end of a resistor, and the other end of the resistor is connected to a small device for power supply. ′ (2) In the portable small device described in claim 1, the circuit C is composed of a resistor A, a Zener diode B, and a diode E, and the anode and cathode of the Zener diode B and diode E are reversed to form an arbitrary circuit. A small portable device characterized by three wires connected in series.