JPH06295346A - Microcomuputer - Google Patents

Abstract

PURPOSE:To enable a microcomputer to be used for a development support device to execute I/O control even when a power supply for the development device is interrupted. CONSTITUTION:Since the microcomputer is provided with a terminal group for executing I/O from/to the outside of the microcomputer, an external power source terminal 105, a dedicated power source terminal 113, and an arbitration circuit 121 for executing arbitration between the two power source, the microcomputer can detect the input of the external power source and execute I/O control by switching the power sources. Thereby even when the power source of the development device is interrupted, power can be supplied from the dedicated power source side, I/O control can be executed and execution history data are obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microcomputer, and more particularly to a power supply control circuit for a microcomputer when a development support device is connected.

[0002]

2. Description of the Related Art Referring to FIG. 3 showing a block diagram of a conventional microcomputer, the microcomputer 201 has a dedicated power supply signal 214 from a dedicated power supply terminal 213.
Power signal supplied through the external power supply terminal 20
5 operates according to a power supply signal input via the external power supply signal 206. External input / output interface unit 207
Indicates that the voltage applied to the external power supply terminal 205 is, for example, 2.7 to
It fluctuates within the range of 6.0 [V]. 5 development support devices
[V] is fixed and the voltage on the development support device side needs to be fixed. Therefore, the input / output control unit 109 and the CPU unit 11 are fixed.
For 6, the dedicated power signal 21 from the dedicated power terminal 213
It is operated by a power supply signal supplied via the terminal 4.

Further, the CPU section 116 is used during normal instruction execution.
When the input / output instruction is executed in, information is input / output via the CPU signal group 115. For the CPU signal group 115 of the information received from the CPU section 116, the input / output control section 1
An input / output control signal 117 is output from the input / output selection terminal 118 to the outside of the microcomputer 201, and an input / output control unit 109 outputs an input / output control signal group 108. The external input / output interface unit 207 outputs a signal obtained by converting the input / output signal group 108 to the voltage level of the external power supply signal 206 input from the external power supply terminal 205 as the internal input / output signal group 104, and outputs the external input / output terminal group 102. External input / output signal group 1 of the microcomputer 201
Data is sent and received from 03.

Further, the input control unit 109 uses the signal group which can be judged by the execution history storage circuit as the internal input / output execution history signal group 1
It outputs to the external input / output execution history terminal group 110 through 12. The output external input / output execution history signal group 111 is written in the execution history circuit without voltage conversion.

Referring to FIG. 4 showing a conventional development support device using the microcomputer, the conventional development support device 301 has the microcomputer 201 shown in FIG. 3 mounted therein for the development support device.

[0006] As a connection form, instead of the microcomputer mounted on the development target device 306, the conventional development support device 30 is connected to the microcomputer connection unit 307.
1 is connected, and the microcomputer 201 mounted in the conventional development support device 301 is the development target device 30.
6 operates on behalf of the microcomputer mounted on 6. At this time, if the development target device 306 has a power input, the power supply signal is the development device power supply signal 308 via the development target device power supply terminal 302 and the development device power supply detection unit 305.
The development device power source detection unit 305 outputs the development device power source signal 308 to output the development support device external power source signal 304 to the external power source terminal 205, and the microcomputer 201 is input from the external power source terminal 205. It is possible to generate a signal to be input / output to / from the external input / output terminal group 102 by the power supply signal.

Next, when there is no power input to the development target device 306, the development device power supply detection unit 305 does not output the development device power supply signal 308 from the development target device power supply terminal 302. Since the power source signal is not input from the external power source terminal 205 to the microcomputer 201 without outputting the signal 304, it becomes impossible to generate a signal to be input / output to / from the external input / output terminal group 102.

Further, the power supply 310 for the development support apparatus is supplied to the microcomputer 201 via the development support apparatus power supply signal 309 to the external power supply terminal 213 of the microcomputer 201. The external input / output signal group 103 and the development target device input / output control terminal 31 input to the development target device input / output terminal group 313 of the development target device 306.
The external input / output control signal 311 input to the external input / output terminal 2 is the external input / output terminal group 1 in the conventional development support apparatus 301.
02 and the input / output control terminal group 118. When the execution history is stored, the data output from the external input / output execution history terminal group 110 is stored in the external input / output execution history signal group 11
The data is written in the execution history storage circuit 303 via 1.

[0009]

The above-mentioned microcomputer is not a problem in normal use, but in the microcomputer development support device, when the power of the device to be developed is cut off, the input / output control of the microcomputer is performed. There was a problem that it would not work.

[0010]

According to the present invention, there is provided an external input / output for controlling input / output processing with the outside of the microcomputer in a microcomputer having an external input / output signal group for input / output processing with the outside of the microcomputer. An interface section, an external power supply signal terminal supplied from the outside of the microcomputer for operating the external input / output interface section, and an input / output control section operated by a signal input from the external input / output interface section, A terminal for a dedicated power supply signal for operating the input / output control unit, a power supply arbitration circuit for arbitrating between the dedicated power supply signal input from this terminal and the external power supply signal input from the terminal for the external power supply signal, An external input / output interface power supply signal line output from this power supply arbitration circuit,
A power supply status terminal for determining whether the external power supply signal is input in the power supply arbitration circuit and outputting the external power supply signal to the outside of the microcomputer, and an input / output CPU connecting the CPU unit inside the microcomputer and the input / output control unit. It is characterized in that it is provided with a signal line group and an external input / output execution history terminal group for outputting to the outside of the microcomputer the value that can be recognized by the microcomputer converted by the input / output interface section.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1 showing a microcomputer of an embodiment of the present invention, this embodiment is a power supply arbitration circuit 121.
3 is the same as that of FIG. 3 except that the same reference numeral is used.

The microcomputer 101 is operated by two power sources, a power source signal supplied from a dedicated power source terminal 113 via a dedicated power source signal 114 and a power source signal supplied from an external power source terminal 105 via an external power source signal 106. To do. The power supply to the external input / output interface unit 107 selects the dedicated power supply signal 114 when the power supply arbitration circuit 121 detects the input state of the external power supply signal 106 and is not input, and selects the external power supply signal 106 in other cases. It is supplied to the external input / output interface unit 107 via the input / output interface unit power supply signal 122. At this time,
The determination result of the determined external power supply signal 106 is output from the power supply status terminal 119 via the power supply status signal 120.

Further, the CPU section 116 is used at the time of executing a normal instruction.
When the input / output instruction is executed in, information is input / output via the CPU signal group 115. In response to the information of the CPU signal group 115, the input / output control unit 109 outputs the input / output selection signal 117 to the outside of the microcomputer 101 from the input / output selection terminal 118, and the input / output control signal group 108,
Data is exchanged with the external input / output signal group 103 of the microcomputer 101 via the external input / output interface unit 107, the internal input / output signal group 104, and the external input / output terminal group 102.

The input / output control unit 109 uses the signal group that can be judged by the execution history storage circuit as the internal input / output execution history signal group 11
2 to the external input / output execution history terminal group 110. The output external input / output execution history signal group 111 is written in the execution history storage circuit without voltage conversion.

Referring to FIG. 2 showing an example of a development support apparatus using the microcomputer 101 of FIG. 1, FIG.
The difference from the conventional development support device using a microcomputer is that the conventional development support device (FIG. 4) detects the power of the development device power supply signal 308 output from the development target device 306 by the development device power detection unit 305. On the other hand, in this development support device (FIG. 2), the development target device 30
The development device power supply signal 308 output from the microcomputer 6 is determined inside the microcomputer 101, and the development device power supply detection signal 413, which can be determined by the development device power supply detection unit 405, is output from the power supply status terminal 119. This is the point where the detection unit 405 can detect the power supply.

In the above description, a group of terminals for input / output processing with the outside of the microcomputer is called an external input / output signal group, and a portion for performing input / output processing with the outside of the microcomputer is called an external input / output interface section. And
A first power supply signal supplied from the outside of the microcomputer for operating the external input / output interface section is called an external power supply signal, and a section for performing an input / output operation by a signal with the external input / output interface section is called an input / output control section. And
A second power supply signal supplied from the outside of the microcomputer for operating the input / output control unit is called a dedicated power supply signal, and a central processing unit inside the microcomputer is a CPU.
A signal group connecting the input / output control unit and a CPU signal group, and a signal group connecting the external input / output interface unit and the input / output control unit is called an input / output control signal group.

[0017]

As described above, according to the present invention, in the microcomputer development support device, even when the power supply of the development device is cut off, the input / output control of the microcomputer can be performed by the power supply from the dedicated power supply side. , Execution history data can be obtained, and high reliability can be secured.

[Brief description of drawings]

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

FIG. 2 is a block diagram of an example of a development support device using the microcomputer shown in FIG.

FIG. 3 is a block diagram of a conventional microcomputer.

4 is a block diagram of an example of a development support device using the microcomputer of FIG.

[Explanation of symbols]

 101, 201 Microcomputer 102 External input / output terminal group 103 External input / output signal group 104 Internal input / output signal group 105, 205 External power supply terminal 106, 206 External power supply signal 107, 207 External input / output interface section 108 Input / output control signal group 109 Input / output control unit 110 External input / output execution history terminal group 111 External input / output execution history signal group 112 Internal input / output execution history signal group 113, 213 Dedicated power supply terminal 114, 214 Dedicated power supply signal 115 CPU signal group 116 CPU section 117 Input / output control signal 118 Input / output control terminal 119 Power supply status terminal 120 Power supply status signal 121 Power supply arbitration circuit 122 External input / output interface power supply signal 301,401 Development support device 302 Development device power supply terminal 303 Execution history storage circuit 304 Development support device External power supply signal 305,405 Development device power supply detection unit 306 Development target device 307 Microcomputer connection unit 308,413 Development device power supply signal 309 Development support device power supply signal 310 Development support device power supply 311 External input / output selection signal 312 Development target device input / output Control terminal 313 Development target device External input / output terminal group 314 Execution history storage circuit input / output terminal group

Claims (1)

[Claims] 1. A microcomputer having an external input / output signal group for performing input / output processing with the outside of the microcomputer, and an external input / output interface section for controlling input / output processing with the outside of the microcomputer, and this external input / output interface section. For operating an external power supply signal supplied from outside the microcomputer, an input / output control unit that operates according to a signal input from the external input / output interface unit, and an input / output control unit for operating the input / output control unit. A dedicated power supply signal terminal, a power supply arbitration circuit that arbitrates between the dedicated power supply signal input from this terminal and the external power supply signal input from the terminal of the external power supply signal, and an external input power output from this power supply arbitration circuit. The output interface power supply signal line and the external power supply signal are input to the power supply arbitration circuit. A power state terminal for determining whether or not to output to the outside of the microcomputer, an input / output CPU signal line group connecting the CPU section inside the microcomputer and the input / output control section, and conversion at the input / output interface section. And a group of external input / output execution history terminals for outputting a value recognizable by the microcomputer to the outside of the microcomputer.