英文资料
Single-Chip Microcomputer dormancy computing reset
and the anti-interference ability is perfect
Abstract:
Introduce a kind of dormancy of using- restore to the throne in the operation way and improve the anti-interference ability method of the one-chip computer,Analyse its scope of application, provide and use the circuit concretely; Combine the instance, analyze the characteristic of the hardware and software design under these kind of operation way.
Keyword: Single-Chip Microcomputer Restore to the throne, dormancy,
anti-interference Preface:
With the development at full speed of the micro electric technique, the
performance of the one-chip computer improves rapidly, demonstrate the outstanding advantage in the operation, logic control, intelligent respect, replaced and enlarged the measuring that the circuit made up, control circuit by digital logical circuit, operation originally to a great extent, use very extensively. But because it have system halted, procedure run critical defect of flying etc, make it limit in a lot of important application of occasion. A lot of technology in anti-interference , for example set up the software trap, add the hardware to guard the gate in dog's circuit etc, can make this problem have better settlement, but still the existing problem: ① Guard the gate dog at the movement, mean and appear mistake already and run some time, this is not allowed in some occasions; ②Procedure appear circulation mistake very much sometimes, but just guard the gate dog control link include and enter, adopt and guard the gate as to such a mistake dog unable to discern; ③ In measure and control cycle among the long system, one-chip computer spend wait for the peripheral hardware a large amount of time, will be interfered too when
carry out and wait for the order. To these situations, we have tried the method restored to the throne voluntarily in practice, alternate pulse of adopting etc or restore to the throne waking according to external terms to the one-chip computer up. After being restored to the throne each time, the one-chip computer carries out the corresponding procedure, enters dormancy in time after finishing carrying out the task, wait to be restored to the throne neatly. Have solved above-mentioned problems well with this method, and has got better result in the agricultural voltage transformer comprehensive protector experiment. Now take 51 serial one-chip computers as an example and probe into the concrete principle and implementation method, restored to the throne the signal as the high level.
1 A principle and implementation method
1.1 Unconditional regular reset
Use timer, special clock chip or other pulse generator in a certain part of the regular produce reset signal. This method is especially suited for measuring instrument; this kind of method is especially suitable for the measuring instrument. In not running actually, sample the analog quantity of introduction with A/D converter often, then store showing. This course is very fast, but steady for reading, the data per second are only upgraded 1 -2 times, a large amount of time of CPU is used for waiting. Let CPU carry out and enter dormancy directly after the task , restore to the throne and wake by external world up It carry out the next operation, this is to restore to the throne the law regularly In this way can make anti-interference ability strengthen greatly , have 2 points mainly: ①. At the dormancy, procedure stop run can appear PC indicator disorderly procedure that causes run and fly. Work time in dormancy proportion 1:9, that is to say 1 s have 0.1 time of s used for measuring, sending off showing, there is time dormancy of 0.9s, the probability that the procedure is interfered is 1/10 while running at full speed, whole anti-interference ability raise by 10 times. ② Because every 1s is
restored to the throne once unconditionally, once present the system halted during a job, can certainly resume when restored to the throne next time. As to only instrument that show, some reading mistake that 1s appear accidentally there is no memory to the next measurement, be could bear, belong to “pass” mistake. This kind is restored to the throne the advantage of dog's circuit for guarding the gate regularly, first, change waiting time into a dormancy state, time to shorten and may be interfered; Second, avoided happening that the dog controls the death circulation of the link to include guarding the gate.
1.2 The external condition is restored to the throne the law
Some arrival that export or measure is controlled by the outside. For instance, the hot form of heating, rotate the pulse produced and calculate heat by hot water wheels, there is no hot water to flow, there is no heat to export, CPU only need in fact keep number value, do not need to count. Can imagine hot water wheels rotate when parking warm , CPU idle in will it be will it be one season autumn spring and summer, If let dormancy its , measure have water wheels pulse constantly, anti-interference ability can strengthen greatly. So, so long as link up the restoring to the throne of the pulse of the water wheels and CPU, the water wheels rotate a circle each time, CPU is restored to the throne once, hot form can work normally , this is restored to the throne the law by the external condition . Similar application have half electron kilowatt-hour meter , go on one count just when the machinery degree wheels and transfers to a circle, users do not need the electricity, CPU has been knowing the dormancy all the time . The restoring to the throne in the interval not to be regular, but confirmed according to the external condition of this method. In some occasions, the time of the dormancy will be very long, very effective to improving anti-interference ability.
2 The hardware realizes the main point
2.1 Restored to the throne regularly unconditionally
Generally it has 2 kinds of methods. ① Use the timer or the special-purpose clock chip to be restored to the throne. Fig1, in order to use the timing circuit that 555 circuit makes up; Can use the clock chips of X1126, etc, wake CPU up with the alarm signal after setting up warning time. This kind of method is suitable when the long interval is made, can also follow the result of this operation ，determine to wake time up in alarm next time temporarily, very flexible and convenient. ② The signal of using the system to be inherent is as reducing the pulse regularly. Use 50Hz worker power make reducing after having a facelift frequently, already omit the timer, gathered the corresponding signal for the phase place which measured the electric current signal at the same time, as Fig. 2 shows.
2.2 External conditions are restored to the throne
Send external condition pulse to and is restored to the throne the end son after having a facelift. To that above-mentioned water wheels or the ammeter spend a pulse produced, can use Schmitt's trigger to have a facelift; For writing down the instrument of the biggest or minimum，can use the window comparator. In order to realize the electrification that is regulated，can use the electronic electric potential device, establish upper and lower limits with the order of the one-chip computer.
2.3 Reduce cycle and restored to the throne the high electricity at ordinary times
In Fig3, restored to the throne the signal during high level Tr, the one-chip computer is in the state of restoring to the throne, the procedure does not run, anti-interference ability is the strongest; After the high level, the one-chip computer begins to hold the conduct procedure. That is to say, are restored to the throne and suitable for the time that the procedure carries out during the low level Td of the signal, this time should be greater than the execution cycle of the procedure each time. It is restore to the throne cycle and restore to the throne high level of signal take empty than very much important
to choose rationally. As to simple to show instrument, restore to the throne cycle determine data break cycle, low electricity is it measure, hence over all time shown to greater than to want at ordinary times; otherwise, it can’t present forever the mistake of the intact executive program. Monolithic integrated circuit in Ts and Tr period all can effectively the antigambling, but is best the unnecessary time arrangement in Tr. When the program time is long, as far as possible the request reduces Tr,it may join the differentiating circuit, like chart 1 center C30, R26, D9.
2.4 Have the electricity to measure and restore to the throne manually
Some systems in its initialization and run-time need first electrical impulses. Restored to the throne and already become the beginning condition of normal running each time while adopting the way of restoring to the throne to run, it is unable to distinguish and have the electricity for the first time. In some pin connects the electric capacity of one Leif to the ground, measure this pin after being restored to the throne, if low level to have electricity for the first time. Give system set up one restore to the throne button, that is to say a common one manual to restore to the throne, this button is not joined and being restored to the throne in the end, is connected in parallel in the electric capacity both ends to the ground of above-mentioned pins.
Result:
Conclusion Anti-interference is an important problem in an electronic design, especially Important in the one-chip computer. This is because the one-chip computer has procedures to run particularity that flies, the consequence that it is interfered may be the system halted, may send out various kinds of mistakes or illegal movements before the system halted too, make the whole system produce the mortality mistake. So, only guarantee it is not enough yet for one-chip computer not to crash, study how to reduce the risk interfered, it can befault-toierant how is it after and make mistakes. This
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