JPH04246737A - In-circuit emulator - Google Patents

Abstract

PURPOSE:To prevent in advance the runaway of an emulator CPU by detecting abnormality of a clock and initializing forcibly the emulator CPU, in the case abnormality is occurred the clock inputted from a target, when execution of a program is being suspended. CONSTITUTION:The emulator is constituted by providing a clock abnormality detecting circuit 1 for detecting abnormality of a clock in an external device of a development object, and an initializing circuit 2 for initializing forcibly an emulator CPU at the time when a clock abnormality signal 103 outputted from this clock abnormality detecting circuit 1 and an execution suspended state signal 113 for showing a fact that execution of a program is being suspended, outputted from a control part 3 are both effective, in the in-circuit emulator provided with the emulator CPU 4.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an in-circuit emulator, and in particular, it is equipped with a pseudo microcomputer (hereinafter referred to as emulator CPU) and is used to control circuits, programs, etc. in an external device to be developed (hereinafter referred to as target). This article relates to an in-circuit emulator used to support the development of.

0002

2. Description of the Related Art A conventional in-circuit emulator has a clock abnormality detection circuit corresponding to a clock input terminal 54, an initialization terminal 55, and a signal group terminal 56, as shown in FIG. 11. Initialization circuit 12
, a control section 13, an emulator CPU 14, and a signal control circuit 15.

The signal group input from the signal group terminal 56 is as follows:
It is connected to the corresponding signal group in the emulator CPU 14 via the signal control circuit 15, and the control section 13
By sending a group of control signals 112 and an execution suspension state signal 113 to the signal control circuit 15, it has a control function including a control function for suspending execution and resuming execution. The operation of this part is a function of a general in-circuit emulator, and a detailed explanation will be omitted.

A clock signal 108 is input from the clock input terminal 54 to the clock abnormality detection circuit 11.
When an abnormality occurs in the clock signal 108 , the clock abnormality detection circuit 11 outputs a clock abnormality signal 110 and inputs it to the control section 13 . In addition, in the initialization circuit 12, an initialization signal 109 inputted from an initialization terminal 55 of a connector (hereinafter referred to as a probe) and a control unit 13
When any of the initialization signals enters the initialization request state in response to the input of the internal initialization signal 111 sent from the emulator C, the CPU initialization signal 114 is output and the emulator C
It is sent to PU14. Note that in a situation where the initialization signal 109 from the probe is inadvertently input while the program execution is suspended, the CPU initialization signal 1
14 is controlled not to be sent to the emulator CPU 14.

That is, in the conventional in-circuit emulator, the control section 13 has the configuration shown in FIG.
In reality, when the clock abnormality signal 110 is detected and an abnormal state occurs, the clock abnormality is dealt with by simple processing such as notifying the operator without performing normal control actions.

[0006]

[Problems to be Solved by the Invention] In the above-mentioned conventional in-circuit emulator, even if a clock abnormality occurs during program execution, this itself is an abnormal state in the target circuit, and the abnormality Emulating the state as it is is out of the question since it is an original function. However, if a clock abnormality occurs while the execution of the program is interrupted, the emulator CPU goes into a runaway state as in the case when the program is being executed. While the execution of this program is suspended, the emulator CPU is in the state of executing the suspended internal processing program that requires accurate execution.
The disadvantage is that the emulator itself cannot be controlled at all.

[0007]

[Means for Solving the Problems] The in-circuit emulator of the present invention includes a pseudo microcomputer that performs pseudo execution of a target microcomputer LSI, and has a function of suspending and resuming program execution. In addition, the microcomputer LSI
In an in-circuit emulator of a type that supports the development of circuits and programs for an external device by inserting a connector having the same terminal shape as that of the external device to be developed, the clock input terminal of the microcomputer LSI a clock abnormality detection circuit that detects an abnormality in a clock signal at a terminal of the connector corresponding to the above and outputs an abnormal signal; an abnormal signal output from the clock abnormality detection circuit; and a signal indicating that program execution is being interrupted. and an initialization circuit for forcing the initialization of the pseudo microcomputer at a valid point in time.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. As shown in FIG. 1, in this embodiment, a clock abnormality detection circuit 1, an initialization circuit 2, a control section 3, and a clock abnormality detection circuit 1, an initialization circuit 2, a control section 3, and It is configured to include an emulator CPU 4 and a signal control circuit 5. Furthermore, shown in FIG. 2 is a logic circuit diagram showing the internal configuration of the initialization circuit 2. As shown in FIG.

As is clear from FIG. 1, in this embodiment, unlike the conventional example described above, the clock abnormality signal 103 output from the clock abnormality detection circuit 1 is also input to the initialization circuit 2. There is. The feature of the present invention lies in this point, and operations other than those related to this point are essentially the same as those of the conventional example.

In FIG. 1, operations during program execution are the same as in the conventional example. Further, even during suspension of program execution, as long as the clock signal 101 input from the clock input terminal 51 is in a normal state, the same operation as in the conventional example is performed. However, when the program is suspended, the clock input terminal 51
When an abnormality occurs in the clock signal 101 inputted from the clock abnormality detection circuit 1, a clock abnormality signal 103 is outputted from the clock abnormality detection circuit 1 and inputted to the control section 3 and the initialization circuit 2. In the initialization circuit 2, as long as the execution interruption state signal 106 is inputted from the control unit 3, when the clock abnormality signal 103 is inputted, the CPU initialization signal 107 is supplied to the emulator CPU4. As a result, if an abnormal state occurs in the clock signal 101 input from the clock input terminal 51, the in-circuit emulator is forcibly initialized via the initialization circuit 2. Runaway behavior can be prevented.

FIG. 2 is a logic circuit diagram showing the internal configuration of the initialization circuit 2 as described above. It has a gate function to enable the abnormal signal 103, and its output signal is input to the delay circuit 7. This delay circuit 7 is a circuit for securing the time necessary to initialize the emulator CPU 4 after the clock abnormality signal 103 returns to normal. The inverting circuit 8 and the AND circuit 9 are logic configuration circuits for making the initialization signal 102 input from the probe initialization terminal 52 valid only while the in-circuit emulator is executing the program. OR circuit 1
0 is the initialization request signal output from the delay circuit 7 and A
A logical OR is performed with the initialization request signal output from the ND circuit 9 to generate and output a CPU initialization signal 107. This CPU initialization signal 107 is input to the emulator CPU 4, and when the clock is abnormal, the emulator CPU
Preventing the PU4 from running out of control has already been explained.

[0013]

As explained above, in an in-circuit emulator, when a clock abnormality occurs in the target while program execution is interrupted, the present invention detects the clock abnormality and forcibly initializes the emulator CPU. This has the effect of preventing the emulator CPU from running out of control.

[Brief explanation of the drawing]

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

FIG. 2 is a logic circuit diagram showing the configuration of an initialization circuit in this embodiment.

FIG. 3 is a block diagram showing the configuration of a conventional example.

[Explanation of symbols]

1, 11 Clock abnormality detection circuit 2, 12
Initialization circuit 3, 13 Control unit 4, 14 Emulator CPU 5, 15 Signal control circuit 6, 9 AND circuit 7 Delay circuit 8 Inversion circuit 10 OR circuit

Claims (1)

[Claims] 1. A pseudo-microcomputer that performs pseudo-execution of the target microcomputer LSI is provided therein, has a function of suspending and resuming program execution, and has the same terminal shape as the microcomputer LSI. In an in-circuit emulator of the type that supports the development of circuits and programs for the external device by inserting the connector into the external device to be developed, the connector corresponding to the clock input terminal of the microcomputer LSI is inserted into the external device to be developed. At a point in time when a clock abnormality detection circuit that detects an abnormality in a clock signal at a terminal and outputs an abnormal signal, an abnormal signal output from the clock abnormality detection circuit, and a signal during program execution are both valid, An in-circuit emulator comprising: an initialization circuit that forces initialization of the pseudo microcomputer.