JPH07302213A - Emulator provided with power source switching circuit - Google Patents

Abstract

PURPOSE:To enable an emulation operation in a state where a user is connected but a power source on the side of the user system is not applied and to enable emulation at the time of applying the power source of the user system. CONSTITUTION:This emulator is provided with a voltage judgement circuit 3 for judging the power supply voltage level of the user system and a power source switching circuit 2 and an emulator power source is switched to a user system power source when the user system power source is a voltage capable of operating a microcomputer 1 for evaluation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is equipped with a power supply switching technology, a microcomputer mounted in a system, or an evaluation microcomputer (hereinafter, referred to as evaluation microcomputer) having a function equivalent to that of the microcomputer. , A technology that is particularly effective when applied to an emulator that enables debugging of a microcomputer application system on behalf of the function of the microcomputer, for example, when the application system that is the target of emulation operates at a power supply voltage of 5V or 3V. For emulators that can emulate both.

[0002]

2. Description of the Related Art In the development of microcomputer application equipment, an emulator is used to debug the application system (user system) and application program (user program) and perform detailed evaluation of the system. As shown in FIG. 4, such an emulator includes an evaluation microcomputer 11 which is connected to a target system and substitutes the functions of the microcomputer, an emulation control unit 12 for realizing emulation and various debugging functions, execution of a user program, A break control unit 13 for setting the trace stop condition and stopping the user program or the trace when the condition is satisfied, the trace memory 14, and the substitute memory lent out when the memory of the application device (user system) is not prepared. A serial interface 16 for performing data communication with the host computer 20 and a master microcomputer 17 for controlling them.
Etc.

The emulator 10 has a user cable 19 connectable to a CPU socket 18 for mounting a microcomputer provided on a board of a target user system. The evaluation microcomputer having the same function as the microcomputer of the user system may be built in the pod portion at the tip of the user cable 19.

In recent years, a microcomputer capable of operating with a power supply voltage of 3V to 5V has been developed. Along with this, as an emulator of an application system using such a microcomputer, a user system has a power supply voltage of 5V or 3V. It is provided with an E7000 H8 / 3003 issued by Hitachi, Ltd., which is configured so that both of them can be emulated by a single unit when operated by
H8 / 3002 H3 / 3042 series emulator user's manual). The emulator employs a method of operating the evaluation microcomputer with the user system power supply when the user system is connected to the emulator. This is because more accurate debugging can be performed by emulating in a state close to the actual operating state.

Specifically, note that some terminals of the user system board to which the user cable extended from the emulator is connected are always set to the ground potential GND when the power switch MS is turned on. And then Figure 3
As shown in, a voltage determination circuit for determining the voltage of the terminal or the signal line of the cable connected to the user cable when the user cable is connected to the emulator and a switch SW which is turned on / off by the output thereof are provided, and If the voltage is at the ground potential, it is determined that the user system is connected, the switch SW is turned on, and the evaluation microcomputer 1
1 is operated by the user system power supply UVcc.

[0006]

However, it has become clear that the conventional method has the following problems. In other words, when the user cable is connected but the user system side power is not turned on, even if the emulator side power is turned on, the user system power is not supplied to the evaluation microcomputer, so the emulation operation is impossible. In particular, it is impossible to emulate when the power of the user system is turned on.

It is an object of the present invention to provide an emulator capable of performing an emulation operation when the power supply of the user system is not turned on. Another object of the present invention is to provide an emulator that can emulate when the user system is powered on. The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0008]

The typical ones of the inventions disclosed in the present application will be outlined below. That is, the present invention provides a voltage determining means for detecting the power supply voltage of the user system, and the power supply voltage supplied to the evaluation microcomputer when the user system power supply exceeds a certain value and the normal operation of the user system becomes possible. The power supply is switched from the power supply to the user system power supply, and otherwise the emulator power supply is supplied to the evaluation microcomputer. Further, the voltage determination circuit is configured such that the constant value can be changed. Further, in the above case, it is desirable to connect a power source stabilizing means such as a capacitor to the power source line to be switched.

[0009]

According to the above means, the emulator power is supplied to the evaluation microcomputer when the user system is not powered on, and the user system power is supplied to the evaluation microcomputer when the user system is powered on. Even when the system is not powered on, the power supply voltage is supplied to the evaluation microcomputer so that the emulation operation can be performed, and the emulation when the user system is powered on becomes possible. Also,
If the voltage determination circuit is configured so that the constant value can be changed, the emulator for evaluation can be emulated by a single emulator even when the evaluation microcomputer operates with a user system power supply of an arbitrary voltage. Further, by connecting a power source stabilizing means such as a capacitor between the power source line to be switched, that is, the power source switching circuit and the power source voltage terminal of the evaluation microcomputer, it is possible to avoid power interruption and voltage drop at the time of switching. it can.

[0010]

1 is a block diagram showing an embodiment of a main part of an emulator having a power supply switching circuit according to the present invention. The emulator power supply EVcc is a power supply for operating the internal logic of the emulator and is normally 5V. The user system 5 is an actual user device that is the target of the emulator, and the user system power supply UVcc is a power supply for operating the internal logic of the user system.
V or 5V. The evaluation microcomputer 11 is a microcomputer mounted on the user system 5 or an evaluation chip having a function equivalent to that of the microcomputer. For example, there is an evaluation microcomputer compatible with a low voltage and having an operating power supply voltage of 3V to 5V.

The voltage determination circuit 3 is a user system power supply UV.
This is a circuit for determining the voltage level of cc and outputs a low level signal when the power supply voltage at which the evaluation microcomputer 11 is operable is set. The power supply switching circuit 2 supplies the power supplied to the evaluation microcomputer 11 according to the signal from the voltage determination circuit 3 to the user system power supply UVcc or the emulator power supply EV.
This is a circuit for switching to cc, and when the signal from the voltage determination circuit 3 is at low level, the user system power supply UV
cc, or emulator power supply E when high level
Vcc is supplied to the evaluation microcomputer 11 as an operating power supply voltage. The power supply switching circuit 2 can be configured by using a relay.

In the present embodiment, in order to avoid power supply interruption and voltage drop at the time of power source switching, between the power source line connecting the power source switching circuit 2 and the power source voltage terminal of the evaluation microcomputer 11 and the ground point. A power source stabilizing capacitor 7 is connected so as to intervene. In addition, the voltage determination circuit 3
Is configured so that the threshold voltage (constant value) can be changed. As a result, even when the evaluation microcomputer operates with the user system power supply of an arbitrary voltage, it is possible to emulate with one emulator.

FIG. 2 shows a user system power supply in the case of applying the above-mentioned power supply switching circuit 3 when emulating a user system operated by a power supply voltage of 4V with an emulator operating by a power supply voltage of 5V. The change in power supply voltage of the evaluation microcomputer 11 at the time of turning on is shown, and the horizontal axis represents time.

Although the emulator power supply voltage EVcc of 5V is initially supplied to the evaluation microcomputer 11, when the main switch MS is turned on, the user system power supply UVc is supplied.
c increases almost linearly with the passage of time. And
When the voltage exceeds 3 V, the voltage determination circuit 3 sends a signal indicating that the emulator has reached the operable voltage to the power supply switching circuit 2 to switch the switch. As a result, the evaluation microcomputer 11 is disconnected from the emulator power supply. At this time, a voltage drop occurs in the evaluation microcomputer input power supply, but since the capacitor 7 is connected, it gradually drops. Then, the user system power supply UVcc is switched before the evaluation microcomputer input power supply becomes 3 V or less, and the power supply voltage supplied to the evaluation microcomputer 11 quickly shifts to 4 V.

On the other hand, since the emulator-side emulation controller 12 and the trace memory 6 shown in FIG. 4 operate on the emulation power supply EVcc (5V),
According to this embodiment, it is possible to acquire the trace data at the time of power-on reset of the user system. In addition,
The user system 5 using the power supply switching circuit 2 of this embodiment
In order to perform the emulation at power-on, the emulator power EVcc is turned on and the user system startup setting is performed, and then the user system power UV
By turning on cc, for example, emulation such as tracing can be performed by a single emulator in a target system having a power supply voltage of 3V and a target system having a power supply voltage of 5V.

As described above, the above embodiment is provided with the voltage judging means for detecting the power supply voltage of the user system, and when the user system power supply exceeds the constant value and the normal operation of the user system becomes possible, the evaluation microcomputer is provided. The power supply voltage supplied is switched from the emulator power supply to the user system power supply, and otherwise the emulator power supply is supplied to the evaluation microcomputer, so when the user system power is not turned on, the emulator power supply is turned on again. When the power is turned on, the user system power is supplied to each evaluation microcomputer, so the power supply voltage can be supplied to the evaluation microcomputer even when the user system power is not turned on, and emulation operation can be performed. At the same time, the emulator for turning on the power of the user system is Shon there is an effect that it is possible.

Further, since the voltage judgment circuit is constructed so that the constant value can be varied, it is possible to emulate it by one emulator even when the evaluation microcomputer operates on the user system power supply of an arbitrary voltage. effective. Further, by connecting a power supply stabilizing means such as a capacitor between the power supply line to be switched, that is, the power supply switching circuit and the power supply voltage terminal of the evaluation microcomputer, it is possible to avoid power interruption and voltage drop at the time of switching. The effect is that you can do it.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say. In the above description, the case where the invention made by the present inventor is mainly applied to the emulator, which is the field of application which is the background of the invention, has been described. However, the present invention is not limited thereto and requires switching of the power supply voltage. The system can be used in general.

[0019]

The effects obtained by the representative one of the inventions disclosed in the present application will be briefly described as follows. That is, according to the present invention, it is possible to switch from the emulator power supply to the user system power supply or from the user system power supply to the emulator power supply without interrupting the power supply to the evaluation microcomputer, so that the emulation when the user system power supply is turned on is possible. Become.
Further, even when the evaluation microcomputer operates with the user system power supply of an arbitrary voltage, it is possible to emulate with one emulator.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a main part of an emulator including a power supply switching circuit of the present invention.

FIG. 2 is a graph showing changes in the power supply voltage supplied to the evaluation microcomputer when the user system power is turned on (when the power is switched).

FIG. 3 is a block diagram showing an example of a power supply switching system in a conventional emulator.

FIG. 4 is a block diagram showing a configuration example of a general emulator.

[Explanation of symbols]

 EVcc emulator power supply, UVcc user system power supply, 2 power supply switching circuit, 3 voltage determination circuit, 5 user system, 7 capacitor, 10 emulator, 11 evaluation microcomputer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuya Suzuki 5-22-1, Kamisuihonmachi, Kodaira-shi, Tokyo Inside Hitachi Microcomputer System Co., Ltd.

Claims (3)

[Claims] 1. A microcomputer installed in the system or an evaluation microcomputer having a function equivalent to that of the microcomputer, the function of the microcomputer is substituted, and the target microcomputer application system can be emulated. In the emulator, a power supply switching circuit that selectively supplies either the power supply voltage of the emulator or the power supply voltage of the application system to the evaluation microcomputer, and a voltage determination circuit that determines the power supply voltage level of the application system. When the power supply voltage of the target application system exceeds a certain value, the power supply voltage supplied to the evaluation microcomputer is switched from the emulator power supply to the application system power supply. An emulator characterized by the following. 2. The emulator according to claim 1, wherein the voltage determination circuit is configured such that the constant value is variable. 3. The capacitor, the one terminal of which is connected to a ground point, is connected between the power supply switching circuit and the power supply voltage terminal of the evaluation microcomputer. The emulator according to claim 1 or 2.