Excavating
Patent
1985-10-03
1987-09-22
Fleming, Michael R.
Excavating
371 62, 371 66, G06F 1104
Patent
active
046960023
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a resetting device for microprocessors. Resetting circuits for microprocessors have been known for a long time. On the one hand, they serve to put the microprocessor in a defined output stage when the voltage supply is applied. On the hand hand, resetting circuits have been already suggested, which cause a resetting of the microprocessor, if the program stored in the microprocessor is not orderly operated. For this purpose signals are generated at an output of the microprocessor. These signals occur once during each running through a program, for example. If these signals fail to occur for a long time a resetting pulse is emitted. However, this process of resetting is not reliable in all cases. For example, a failure of the microprocessor may occur when a jump occurs in the program range of the data range (RAM or ROM). The program order is defined by the data stored in the data range. Thus, endless loops can form to which an output of the microprocessor can respond. Although the microprocessor does not function properly no resetting is provided in the known circuits, since pulses are present at the output of the microprocessor. This can result in that the device operated by the microprocessor does not work. In the worst case damages may occur in the device, namely when consumers are switched on, which by definition are only charged for a short time, so that an erroneous circuit of the microprocessor is permanently charged.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a resetting device which is advantageous in that a monitoring of the operability of the microprocessor in dependence from cyclically applied input signals is performed. If a predetermined, defined reaction of the processor is not triggered by an input signal within a given time, it is to be assumed that the microprocessor does not operate sufficiently. For this purpose it is immaterial how the signals appear at the defined output. An error is recognized if a defined time sequence does not occur between the cyclic input signal and the signal at the output.
Advantageously, a switch may be provided which suppresses signals for a short time. Thus, the total resetting circuit can be simply constructed. Switching means for the control of a microprocessor may be already installed, so that signals which are generated for a short time and which are caused by switching conditions can be suppressed. It is also favorable to lock the switch for a predetermined time when a single signal occurs. In this manner it is possible to evaluate the time delay between the signal to be put in and the reaction of the output. If the output has not reacted within a predetermined time, the resetting pulse is triggered by opening of the switch.
For securing the endangered consumer if the cyclic input signal is missing or during the program throughput it is advantageous to evaluate at least a further output of the microprocessor, if it remains longer in its predetermined position. The triggering of the resetting pulse is simply carried out by charging or unlocking of a condensor by means of resistors. The use of monostable tilting members is also possible and advantageous. In order to obtain a quick switching off of the reset pulse it is advantageous to bridge the one part of the resistors for loading and unloading the condensor with diodes. Thus, a quick re-running of the microprocessor can be obtained after a case of interference.
The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a first exemplified embodiment of the invention;
FIG. 2 shows a diagram for clarifying the invention,
FIG. 3 shows
REFERENCES:
patent: 4528629 (1985-07-01), Breitling
patent: 4538273 (1985-08-01), Lasser
patent: 4586179 (1986-04-01), Sizari
patent: 4586180 (1986-04-01), Anders
Bauer Bernhard
Langner Arnd M.
Mayer Ulrich
Schleupen Richard
Fleming Michael R.
Robert & Bosch GmbH
Striker Michael J.
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