JPH0944277A - Microcomputer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use an input terminal jointly not only as a terminal dedicated to power source supply control but also as an input terminal in an ordinary operating mode by easily executing the power source supply control to plural function blocks. SOLUTION: When an input signal latched by a latch circuit 10 is an H level, input signals from input terminals 5 and 6 are outputted to a decoder 7 and when the input signals are at M and L levels, they are outputted as ordinary operating mode signals and based on control signals for which the input signals are decoded by the decoder 7, the switching of power source supply to plural function blocks 3 and 4 is controlled by switches 100-103 for power source switching.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microcomputer having a plurality of functional blocks.

[0002]

2. Description of the Related Art In some microcomputers having a plurality of functional blocks, power supply to each functional block is controlled in order to save power. In addition to the above power saving, such control of power supply is also advantageous from the viewpoint of defect analysis for identifying a defective portion such as excessive power supply current.

Although there has been a conventional method of controlling the power supply by software, in this case, only the contents programmed in advance can be controlled.

In particular, in a microcomputer having a mask ROM built-in, the contents once programmed cannot be changed, which is inconvenient during failure analysis. In addition, since a microprocessor (CPU) is used, it is impossible to control when there is a problem with this microprocessor.

FIG. 3 is a block diagram showing such a conventional microcomputer, in which 1 is a positive power source and 2 is a power source.
Is a ground power supply, 15 is a microprocessor, and 3 and 4 are independent functional blocks. These functional blocks 3 and 4 are switches 100 and 101 for switching the power supply which are turned on and off in response to the output of a register described later. Also, it is connected between the positive power source and the ground power source 2 via the power source switching switches 102 and 103.

That is, the switches 100, 1 for switching the power source
Reference numeral 02 connects the respective functional blocks 3 and 4 to the positive power source 1, and the power source switching switches 101 and 103 respectively connect the respective functional blocks 3 and 4 to the ground power source 2.

Reference numeral 14 is the register described above, and the switches 100 to 1 for switching the power supply are selected according to the data written from the microprocessor 15 through the signal line p.
The control signals c and d for controlling the operation of No. 03 are output.

That is, the register 14 receives the signal from the microprocessor 15 and outputs the control signals c and d as shown in Table 1. Therefore, the switches 100 to 103 for switching the respective power supplies are controlled by the control signal c. , D is ON when H level, and OFF when L level.

[0009]

[Table 1]

Next, the operation will be described. If, for example, data "01" is written from the microprocessor 15 to the register 14, the control signal c goes to L level and d goes to H level.
01 is turned off. Therefore, functional block 3 and positive power supply 1
And the ground power supply 2 is disconnected, and the power supply to the functional block 3 is stopped.

On the other hand, the switch 1 for switching the power source
02 and 103 are turned on, the functional block 4 is connected to the positive power source 1 and the ground power source, and the functional block 4
Power supply to the That is, the power supply to each of the functional blocks 3 and 4 is independently controlled.

As another conventional technique, there is a power supply control device in which a dedicated external terminal for power supply control is provided to enable external control. This is easy to control because power supply control to each functional block can be performed externally without using software, but it is difficult to apply it to a microcomputer with a small number of terminals because a dedicated terminal is required.

FIG. 4 is a block diagram showing such a conventional power supply control device. The same components as those shown in FIG. 3 are designated by the same reference numerals, and their duplicate description will be omitted. In FIG. 4, 5 and 6 are switches 1 for switching the power source.
The input terminals are control inputs for controlling 00 to 103, and the control inputs a and b from the input terminals 5 and 6 are input to the decoder 7.

The decoder 7 receives the control inputs a and b as inputs, decodes them, and switches 10 for power supply switching.
The control signals c and d for controlling 0 to 103 are output.

That is, as shown in Table 2, the decoder 7 receives the control inputs a and b and outputs the control signals c and d. Therefore, the switches 100-103 for switching the power supply (control signal c, As shown in Table 2, it is turned on and off when d is at H level and is at L level.

[0016]

[Table 2]

Next, the operation will be described. Now, the control input a of the input terminal 5 is L level, and the control input b of the input terminal 6 is
Is at the H level, the control signal c is at the L level and the control signal d is at the H level.

Therefore, the switches 100, 1 for switching the power source
01 is OFF, and the switches 102, 1 for power supply switching
03 is turned on. That is, the power supply to the functional block 3 is cut off, and the power is supplied only to the functional block 4.

A technique similar to the power supply control device shown in FIG. 4 is disclosed in, for example, Japanese Patent Laid-Open No. 6-232349.

[0020]

Since the conventional microcomputer and power supply control device are configured as described above, in the conventional example of FIG. 3, the power supply control to each functional block is performed by software. , Not only control of pre-programmed contents, but especially mask ROM
With the built-in type, there is a problem in that the contents of the program cannot be changed, it is inconvenient for failure analysis, and if the microprocessor itself malfunctions, power supply control becomes impossible.

Further, in the conventional example of FIG. 4, since power supply to each functional block can be performed externally without using software, power supply control is facilitated, but since dedicated terminals are required, the number of terminals is increased. There was a problem that it was difficult to apply to a microcomputer with few.

The present invention has been made in order to solve the above problems, and makes it possible to easily control the power supply to a plurality of functional blocks without using software, and to facilitate the analysis of defective points. An object of the present invention is to obtain a microcomputer that can be used together with an input terminal in a normal operation mode without using the input terminal as a dedicated terminal for power supply control.

Further, according to the present invention, the input terminals for controlling the power supply can be commonly used as the input terminals for a smaller number of normal operation modes, and in particular, the microcomputer can be used for a microcomputer having a small number of terminals. Aim to get a computer.

[0024]

According to a first aspect of the present invention, there is provided a microcomputer having a ternary input terminal capable of recognizing a three-level input and a latch circuit for latching an input signal from the ternary input terminal. When the input signal latched by the latch circuit is at H level, the input signal from the input terminal is output to the decoder as the power supply control mode signal,
A switch for mode switching that switches the output of the input signal as a normal operation mode signal at the M level and L level is provided, and the power supply is switched based on the control signal obtained by decoding the input signal by the decoder. This switch selectively controls power supply to a plurality of functional blocks.

According to a second aspect of the present invention, when the input signal latched by the latch circuit is at the H level, the input signal from the input terminal is output to the serial register as the power supply control mode signal, and the M level, L level. Based on a control signal obtained by decoding the serial data of the input signal temporarily stored in the serial register by providing a mode switching switch that is switched to output the input signal as a normal operation mode signal when the level is set. Thus, the switch for switching the power supply selectively controls the power supply to the plurality of functional blocks.

[0026]

When the input from the ternary input terminal is at the H level, the microcomputer latches the reset input signal at the rising edge of the reset input signal to cause the microcomputer to enter the power supply mode to switch the mode. A control signal obtained by decoding a control input input from an input terminal via a switch for power supply enables power supply to any of the plurality of functional blocks and suppresses power loss.

When the input from the ternary input terminal is at the M level or the L level, the input from the input terminal is sent to another signal line as a normal input signal via the mode switching switch. Derivable and available.
That is, the input terminal does not need to be a dedicated terminal for power supply control, and can be used as a normal input terminal except in the power supply control mode.

In the power supply control mode, the microcomputer according to the second aspect of the present invention temporarily stores the control input from the input terminal in the serial register as serial data through the mode switching switch, and the serial register stores the control input. A control signal corresponding to the lower bit and the upper bit is obtained through a decoder, and the control signal enables power supply to any of the plurality of functional blocks. This makes it possible to use only one of the above input terminals by using the serial register.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1. An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a positive power supply, 2 is a ground power supply, 3 and 4 are functional blocks, 5 and 6 are input terminals of control inputs a and b, and 7 are switches 100 to 103 for switching respective power supplies.
A decoder for outputting control signals c and d for controlling
These are the same as those shown in FIG.

Further, 8 is a ternary input terminal for recognizing 3-level input, 9 is a reset terminal, and 10 is an output value of the ternary input terminal 8 latched by a rising edge (or a falling edge) of the reset input signal. It is a latch circuit.

Of the three levels from the ternary input terminal 8, the H level input signal is used to switch and supply the input signals from the input terminals 5 and 6 to the decoder 7.
The M level and L level input signals are used in the normal operation mode of the microcomputer.

The microcomputer of this embodiment has a power supply control mode determined by the output of the latch circuit 10.

When the input signal level from the ternary input terminal 8 is set to the H, M and L levels as described above, these inputs are recognized as normal terminal inputs via the signal line i. , Is latched by the latch circuit 10 at the rising edge of the reset input signal k at the reset terminal 9, is used to determine the power supply control mode, and is used to control the mode switching switches 104 and 105.

The mode switching switches 104 and 105 connect the control inputs a and b from the input terminals 5 and 6 to the decoder 7 when the above-mentioned power supply control mode is determined, and otherwise, normally. Is connected to the path used in the operating state, that is, the signal lines g and h.

That is, the control inputs a and b are changed by switching the mode switching switches 104 and 105.
Is output to the decoder 7 via the signal lines e and f, or to the normal path via the signal lines g and h.

Therefore, in the microcomputer of this embodiment, the input from the ternary value input terminal 8 is latched by the latch circuit 1 at the rising edge of the reset input signal from the reset terminal 9.
Output j latched by 0 and latched by this latch circuit 10
Is H, the power supply control mode is set, and when M and L, the normal operation mode is set.

In the power supply control mode,
The mode switching switches 104 and 105 are switch-connected to the decoder 7 side, and in the normal operation mode, the mode switching switches 104 and 105 are connected to the signal lines g and h which are paths in the normal operation.

Next, the operation will be described. Now, assuming that the reset input signal from the reset terminal 9 changes from the L level to the H level when the input from the ternary input terminal 8 is at the H level, the latch circuit 10 has the H level due to the rising of the reset input signal. Is latched.

Therefore, the microcomputer of this embodiment enters the power supply control mode as described above,
The mode switching switches 104 and 105 are switched and connected to the decoder 7 side.

Therefore, in such a state, for example, the control input a of the input terminal 5 is L level, and the control input b of the input terminal 6 is
Is at the H level, the signal on the signal line e is at the L level and the signal on the signal line f is at the H level as shown in Table 3, so that the control signal c is at the L level and the control signal d is at the H level. Becomes

[0041]

[Table 3]

As a result, the power switch 100,
101 is turned off, and the switch 102 for power supply switching,
103 is turned on, power supply to the functional block 3 is cut off, and power is supplied only to the functional block 4.

On the other hand, the input from the three-valued input terminal 8 is M
At the level or the L level, each of these levels is latched by the rising of the reset input signal. Therefore, the microcomputer outputs the inputs of the input terminals 5 and 6 to the signal lines g and h in the normal operation mode.

That is, the switch 10 for mode switching
By providing 4, 105, there is an advantage that the input terminals 5, 6 do not need to be dedicated terminals for power supply switching and can be used as normal input terminals in a mode other than the power supply control mode. Of course, the three-value input terminal 8
Can also be used as a normal terminal other than for mode setting.

Embodiment 2 FIG. 2 shows another embodiment of the present invention, in which the same components as those shown in FIG. 1 are designated by the same reference numerals, and the duplicate description thereof will be omitted. Further, the microcomputer of this embodiment has a power supply control mode determined by the output of the latch circuit 10 as in the first embodiment.

In FIG. 2, reference numeral 104 supplies the control input a of the input terminal 5 to the serial register 11 described later in the power supply control mode in which the output j of the latch circuit 10 becomes H level, and otherwise, during normal operation. It is a mode switching switch for switching and supplying to the signal line g which is a path used. That is, the control input a is connected to the normal path via the serial register 11 via the signal line 1 or the signal line g.

Reference numeral 11 denotes the n-bit serial register, which receives a control input input via the signal line 1 as serial data and sends it to the decoder 12 described later via the signal line m at a constant clock timing. To send.

The decoder 12 also decodes the output m of the serial register 11 and outputs control signals c and d for controlling the switches 100 to 103 for power supply switching. Reference numeral 13 is a clock generation circuit, which supplies an operation clock to the serial register 11 via a signal line o.

That is, in the microcomputer of this embodiment, the input from the ternary input terminal 8 is latched in the latch circuit 10 at the rising edge of the reset input signal k from the reset terminal 9, and the output latched by the latch circuit 10 is output. Is H, the power supply control mode is determined, and M,
When it is L, the normal operation mode is determined.

In such a power supply control mode, the mode switching switch 104 is connected to the serial register 11 via the signal line l, and in the normal operation mode,
The mode switching switch 104 is connected to the path during normal operation. Here, the serial register 11 has n = 2 bits.

Next, the operation will be described. Now, if the input from the reset terminal 9 changes from the L level to the H level when the input from the ternary input terminal 8 is at the H level, the H level is latched in the latch circuit 10 by the rising edge of the reset input signal. It

Therefore, the microcomputer of this embodiment enters the power supply control mode and connects the mode switching switch 104 to the serial register 11.

Therefore, for example, assuming that the lower bit (n = 1) of the serial data as the control signal input from the input terminal 5 is L and the upper bit (n = 2) is H, the input of the decoder 12 will be described. Becomes L and H, the control signal c becomes L and the control signal d becomes H, as shown in Table 4.

[0054]

[Table 4]

As a result, the power switch 100,
101 is turned off, and the switch 102 for power supply switching,
103 is turned on, power supply to the functional block 3 is cut off, and power is supplied only to the functional block 4.

That is, although a plurality of input terminals are required to control the power supply in the first embodiment, the serial register 11 for storing the serial data input to the input terminal 5 is provided in this embodiment. This has the advantage of requiring only one input terminal.

In the above-described first and second embodiments, the switch 100, 102 for switching the power source controls whether each functional block 3, 4 is connected to or disconnected from the positive power source 1. The configuration for controlling whether to connect or to connect to the ground power supply 2 is also optional.

[0058]

As described above, according to the invention of claim 1, a ternary input terminal capable of recognizing an input of three levels, and a latch circuit for latching an input signal from the ternary input terminal are provided. , The input signal latched by the latch circuit is H
A switch for mode switching which is switched to output the input signal from the input terminal to the decoder as a power supply control mode signal when the level is set, and to output the input signal as a normal operation mode signal when the level is M level or L level. Is provided, and the switch for power supply switching is configured to selectively switch power supply to a plurality of functional blocks based on a control signal obtained by decoding the input signal by the decoder. It is possible to easily implement power supply control for multiple functional blocks.
There is an effect that it is possible to facilitate the analysis of a defective portion and obtain a terminal that can be used as an input terminal in a normal operation mode without using the input terminal as a dedicated terminal for power supply control.

According to the second aspect of the present invention, when the input signal latched by the latch circuit is at the H level, the input signal from the input terminal is output to the serial register as the power supply control mode signal, and the M level and L level signals are output. When the input signal is switched to output as a normal operation mode signal, a mode switching switch is provided, and based on a control signal obtained by decoding the serial data of the input signal temporarily stored in the serial register, Since the switch for power supply switching is configured to selectively switch power supply to a plurality of functional blocks, the input terminals for power supply control can be operated with a smaller number of input terminals for normal operation modes. There is an effect that it can be used for both purposes, and in particular, it can be used for a microcomputer with a small number of terminals.

[Brief description of drawings]

FIG. 1 is a block diagram showing a microcomputer according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a microcomputer according to another embodiment of the present invention.

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

FIG. 4 is a block diagram showing a conventional power supply control device.

[Explanation of symbols]

3,4 Functional block, 5,6 Input terminal, 7,12
Decoder, 8 3-value input terminal, 10 latch circuit, 11
Serial register, 100-103 Power switch, 104, 105 Mode switch.

Claims (2)

[Claims] 1. A ternary input terminal capable of recognizing a three-level input, a latch circuit for latching an input signal from the ternary input terminal, and an input signal latched by the latch circuit are at an H level. A switch for mode switching which is switched to output the input signal from the input terminal to the decoder as a power supply control mode signal at the time of, and output the input signal as a normal operation mode signal at the M level and the L level. A microcomputer provided with a switch for selectively switching power supply to a plurality of functional blocks based on a control signal obtained by decoding the input signal by the decoder. 2. A ternary input terminal capable of recognizing an input of three levels, a latch circuit for latching an input signal from the ternary input terminal, and an input signal latched by the latch circuit is at an H level. At this time, the input signal from the input terminal is output to the serial register as a power supply control mode signal, and M
A switch for mode switching which is switched so as to output the input signal as a normal operation mode signal at the time of level or L level, and a control signal obtained by decoding serial data of the input signal temporarily stored in the serial register. A microcomputer provided with a power supply switching switch for selectively switching control of power supply to a plurality of functional blocks.