JPS6059598A - Data writing/reading device in/from eeprom - Google Patents

Abstract

PURPOSE:To reduce the number of I/O signal lines by forming a circuit for switching and connecting I/O signal lines from respective I/O devices in a main device to a processor unit on the external device side. CONSTITUTION:When the external device 200 is not connected to the main device 100 and a switch SW1 is opened, the 2nd inputs of an AND1 and an AND2 are ''1'' respectively, the 2nd inputs of an AND3 and an AND4 are ''0'' and the main device 100 integrates output pulses from a sensor 14 and sends the integrated result to a display circuit 16. When the device 200 is connected to the main device 100 and the SW1 is closed, the 2nd inputs of the AND1 and AND2 are turned to ''0'' and an input from the sensor 14 to the processor unit 10 and an output from the unit 10 to the circuit 16 are cut off, the I/O terminals of the units 10, 20 are connected with each other and the unit 20 writes/reads out data in/from an EEPROM13 through the unit 10.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides electrical erasing/writing-1-,
- EEPR, which is a non-volatile memory that can be read and read;
The present invention relates to a writing and reading device that externally controls writing and reading of data to and from an EEPROM in a system using an OM.

[Prior art]

Since EEFROM can be electrically erased, written to, and read freely and is nonvolatile, it can be used, for example, as a counting unit to count the noise that occurs every certain distance, which was previously considered difficult. To make it possible to digitize an odometer, or to create variation products with the same basic routine (specifications) but with various calculation formulas and constants, store subroutine programs and various variation constants to increase the versatility of the system. It becomes possible to expand dramatically.

By the way, when EEFROM is used in such a system, before it is installed in an individual main device such as an odometer, it is necessary to set the initial value of the data area as a counter as described above, write a subroutine program, and store the garbage. The method of reading data is problematic.

As shown in FIG. 1, a commonly considered method for this purpose is to provide a processor unit (10) constituting the main device 10G with an external connection terminal, and to include a processor unit (20) that performs the above writing and reading. There is a method of connecting an external device 200 to enable external control. In the figure, 11 is a ROM that stores the execution program of the processor unit 10, 12 is a RAM that stores calculation data, and 13 is an EEFROM. Earthenware [10
G is, for example, an electronic odometer, 14 is a sensor that sends out a pulse generated every fixed distance traveled, 15 is an interface circuit, and 16 is a display circuit equipped with a display that displays the cumulative travel distance. Further, Dl is a data signal exchanged between the processor unit 10 and the EEPROM 13, A1 is an address signal specifying a specific area of the EEFROM 13, and cl is a control signal instructing writing, reading, etc.

On the other hand, the external device 200 includes a keyboard 21., in addition to the processor unit 2. Printer 22. Monitor display circuit 23
and a changeover switch sw1, for example, made of earthenware [10
By the act of connecting the connection part of this external device @ 200 corresponding to the predetermined connection part of G, the changeover switch SW,
As a result, control of the EEFROM 13 is transferred to the processor unit 20, and the printer 22. Output to the monitor display circuit 23 becomes possible.

However, in the above configuration, switching to external control is performed only by connecting the connector, and although it has the advantage of a simple mechanism and structure, especially when a 4-bit 1-chip microcomputer is used as the processor unit 10, data Since there is no bus, separate input/output signal lines are required for connection with external equipment [200].

[Object and structure of the invention]

The present invention was developed based on these circumstances, and its purpose is to provide sensor input on the main device side.

An object of the present invention is to provide a data writing/reading device for an EEPROM in which the number of input/output signal lines is reduced by sharing input/output signal lines such as display/output lines for connection with external devices.

In order to achieve such an object, the present invention connects an external device to the main device so that the input/output signal line connected to the same output terminal of the processor unit on the main device side constitutes the main device. A switching circuit is provided to switch and connect various input/output devices to a processor unit on the external device side. Hereinafter, the present invention will be explained in detail using Examples.

〔Example〕

FIG. 2 is a block diagram showing an embodiment in which the present invention is applied to a system having an electronic odometer as the main device. In the figure, main device #100 and its constituent first processor unit 10, ROM 11, and RAM
12, EEPROMl3, sensor 14゜interface circuit 151 display circuit 16, and external device 2
00 and the second processor unit 2 constituting it
0. Keyboard 21. Printer 22, monitor display circuit 2
3 is basically the same as that in FIG. Data DI
, address signal A1° and control signal C1. Further, the changeover switch SW is also turned on by the act of connecting the external device 200 to a predetermined connection part of the main device 100. In contrast, in this embodiment, the main device 100
On the side, there is an AND circuit whose first input terminal is connected to the sensor 14 and whose second input terminal is connected to the ground terminal via the connector connection part by turning on the switch 8W. By turning on the switch BV&'+, the first input terminal is connected to the ground terminal and the first input terminal is connected to the first input terminal.
The first processor unit includes an AND circuit AND connected to the output terminal of the first processor unit, and an OR circuit OR, the output terminal of which is connected to the input terminal of the first processor unit. At the same time, on the external device 200 side, the first input terminal is connected to the output terminal of the second processor unit 20, and the second input terminal is connected to the ground terminal via the inverter IN by turning on the switch SW1. AND circuit AN connected to
D, and also the second input terminal are connected to the ground terminal via the inverter INI by turning on the switch SW1, and the first input terminal connects the connector connection portion to the output terminal of the first processor unit 10. It has an AND circuit AND4 connected through the circuit. The OR circuit OR, has the output of the AND circuit AND as its first input, and also connects the AND circuit AN via the connector connection part.
The output of D s is used as the second input, and the AND circuit AND
, are connected to the display circuit 16, and an output terminal of the AND circuit AND4 is connected to the output terminal of the second processor unit 200A.

Therefore, in the above configuration, when the external device 200 is not connected to the main device 100 and the switch SWt is in the open state, the second
The inputs of both are 1'', while the AND circuit AND,
and the second input of AND4 is 0”, made @10
0 counts the pulse input from the sensor 14 as an independent system and displays the integrated value on the display of the display circuit 16. performs normal operation as a child odometer.

On the other hand, as shown in the figure, the external device 200 is connected and the switch history! When fC is input, the AND circuit AN
Since the second input of D1 and AND is 'On, the input from the sensor 14 to the first processor unit 10 and from the first processor unit 10 to the display circuit 16 are
Instead, the output terminals of the first processor unit 10 and the second processor unit 200A are connected to each other via a connector connection part, and the output terminals of the first
The second processor unit can write and read data to and from the EEPROM 13 via the processor unit 10 of the second processor unit 10.

The above is an example in which the switching circuit is configured with a gate circuit, but FIG. 3 shows an example in which a tri-state bus driver is used. In the figure, switch SW1 is the same changeover switch as in FIG. 2, and 24 is an interface circuit. Here, 17 is a tri-state bus driver which opens the input terminal from the sensor 14, the output terminal to the display circuit 16, etc. in response to the turning on of the switch SW1. As mentioned above, in the method using gate circuits, each input/output terminal is fixed as an input terminal for output, but according to this embodiment, since the operating characteristics of the tristate bus driver are bidirectional, , if the total number of inputs and outputs is the same, each terminal can be used as an input terminal or an output terminal depending on the case, so this is especially true in systems where the data input frequency and output frequency are unbalanced. It has the advantage of being efficient to use.

〔Effect of the invention〕

As explained above, according to the present invention, by connecting an external device to the main device, the input/output signal lines connected to the same person output terminal of the processor unit on the main device side can be By providing a circuit that switches and connects the output device to the processor unit on the external device side, the same person's output signal line can be used both inside the main device and for connecting to the external device. Compared to the method of using dedicated input/output signal lines, it is possible to reduce the number of input/output signal lines.

[Brief explanation of drawings]

Figure 1 is a diagram showing a general configuration example of a device for writing and reading data from outside the system to and from EEFROM.
The figure is a circuit diagram showing one embodiment of the invention, and FIG. 3 is a circuit diagram showing another embodiment of the invention. 100... e main device, 200... external device, 10
...First processor unit, 13...Fist EE
PROM, 14--Sensor (input device), 16--
... Display circuit (output device [), 1T... Tri-state bus driver that constitutes the switching circuit, 20 fists, fists, second processor unit, SW□... Closed by connecting external devices Changeover switch, AND 1 to AND 4
・・・AND circuit that constitutes the switching circuit, IVI・
-...Inverter, OR1@・φ・OR circuit. Patent applicant Koito Seisakusho Co., Ltd. Agent Yamakawa Suzuha (and 1 other person)

Claims (1)

[Claims] [
The second one writes and reads data to FROM.
In a system consisting of an external device equipped with a processor unit of 1. A data writing and reading device for an EEPROM, characterized in that a switching circuit is provided for switching connection to two processor units.