JPS6336303A - Microcomputer system - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides, for example, a rotation speed determined by a sensor,
A microcomputer system to be installed in an internal combustion engine control device for controlling and adjusting functions such as fuel injection of an automobile according to working values of load pressure, accelerator pedal, etc., the signal line being the microcomputer system. and the output of the system is optionally connected to an operating unit, a signal display unit, etc. via a control circuit, the microcomputer system comprising at least two microcomputers, in which case tasks are individually assigned to these computers, It also concerns, for example, a variable memory provided for data relating to the engine and the motor vehicle.

Today, microcomputer systems are installed in many fields, and they are becoming increasingly complex due to the ever-increasing demands on the rapid processing of large numbers of accumulated data. In most cases, high requirements are set to reduce the frequency of errors and failures.This problem will be explained below using the example of control equipment for diesel engines, but it also applies to many other fields, such as the field of medical equipment. A similar problem is occurring.

For example, in the case of a diesel engine, the control unit controls the fuel injection quantity, injection timing, exhaust gas recirculation, etc., depending on different variables, with the control circuit controlling the regulation speed of the injection pump, for example via a stepping motor. is activated. Work data such as engine speed, water temperature, load pressure, and fuel temperature is sent to the microcomputer system via various sensors.

Due to the mode of operation of diesel engines, the demands placed on the reliability of the operation of electronic control systems are significantly higher than with conventional automatic electronic systems. Diesel engines, for example, can be destroyed even when there is no load and only a small amount of fuel is injected. However, if the control device malfunctions, a serious accident may already occur before the diesel engine reaches a rotational speed that would destroy it. Therefore, in parallel with the use of unique control electronic technology known in the past, considerations have been made to stop the engine when the rotational speed is exceeded, but in order to actually equip such a control device, it is necessary to It cannot be said that it is sufficient to guarantee the required safety against target and proboscis damage.

Furthermore, a method is known in which two computers are operated in parallel and the results are compared. However, it is very uneconomical to install two computers in this way, and the comparison results are also erroneous;
It is not because both computers are both wrong; we know that only one of both 'computers is wrong and the other is working correctly.

One particular problem when installing microcomputers in motorized vehicles is that electrical failures can occur that can cause the system to malfunction or cause complete program failure. The control devices known so far are operated by a single microcomputer and at least an external program memory (EPROM), but the problem is that the address and data bus is external, as in the case of microprocessors. The so-called “multi-chip”
microcomputer system. This means that electrical disturbances are very easily detected. Data communication on the address data bus occurs at small levels and very quickly, so the probability of failure is extremely low. Any large disturbance peak may lead to errors in the program or data, and thus the entire program may be dumped.

A so-called watchdog circuit is known for automatically restarting a microcomputer when a program crashes. This is a counter having a predetermined counter capacity, and returns a signal generated by software to an initial value from a microcomputer.

In case of a program fall, it is desirable that the reset signal pauses and then the counter overflows, causing the microcomputer to reset via the reset signal and start from scratch in the program. However, this method cannot be said to be reliable. This is because, with this method, the watchdog circuit may not be triggered in the event of a malfunction.

Terminals (ports) necessary for external storage devices such as program memory are lost when the microcomputer is actually used. They have to be recouped at the expense of cost, area and power losses by adding so-called boat-expansion equipment, which requires an even more expensive power supply and ultimately a larger casing with cooling fins. You will need it. For example, when trying to connect external program memory to 4, first 13 address lines,
Eight more data lines are required, leaving a total of 21 terminals to control the original device. Since most commercially available microcomputers only have 32 terminals in total, 11 additional terminals remain for control.

Furthermore, it is known to connect several processors with a common memory to a common bus, and also to connect further one-chip microcomputers and draw in serial interfaces, which are often provided on a chip. . As long as the variable values are stored in separate memories, they are controlled via the existing bus. However, variable values and programs are often stored in the same memory.

The control device for an internal combustion engine known from EP-A-127789 contains exactly two microprocessors, to which different tasks are assigned. A bus system is provided between both processors. “Personal Peelom (FRO)
M) Stores J engine or motor vehicle data and is connected to the first microprocessor via another bus. The first microprocessor can therefore directly access the variable memory, whereas the second microprocessor can only access it via the first processor. However, this also means that the first processor is subjected to additional load,
On the other hand, this means that the access time to variable memory becomes longer.

“Electronic Technology J (1982, No. 4, No. 55-62)
Page) describes various multiprocessor systems. In that case, the individual microprocessors are arranged with a common memory via a common bus. (FIG. 6 in the same document) When the bus is common, a problem arises in the common data communication and address communication, that is, the internal bus of the computer through which program information also runs. However, as a result, similar systems are prone to failures, as already mentioned above as a major drawback.

An object of the present invention is to provide a microcomputer that has high universal efficiency when installed in a motorized vehicle, has extremely high safety against failure, and is advantageous in terms of safety, cost, reliability, and footprint. It's about creating a system.

The purpose of this was to create a microcomputer system of the first type mentioned, in which individual microcomputers together with variable memory in the form of plug-in modules were combined into a single bidirectional address bus and internal address and data buses. This can be achieved by a connection to a data bus which has an unrelated purpose exclusively for data exchange.

In contrast to the arrangements according to the prior art, in the case of the invention the address and data buses of the individual computers are never connected to the outside world. Rather, they are located on a 2.3 mm square chip. The advantage of this is that the possibility of interference is almost completely eliminated, i.e. the risk of the program falling off due to electrical irradiation is physically eliminated. will be done.

In the case of a diesel engine control system, such program failure can cause the engine to overspeed and endanger human life. Conventional systems cannot be safely protected even by expensive shielding measures or interference filters, so for example the already mentioned watchdog circuits are used.

The first thing you need to do is assign tasks to different computers.
This means that all these computers can work at the same time. Even if a very powerful computer existed, if there was only one computer, the entire task would have to be integrated into a complex program structure. This is because the computer can only process one task at any given time.

The advantage of assigning tasks to different computers is that, as in the above case, the signals must be processed in a rapid sequence so that any malfunction is detected and, if necessary, the engine emergency stop device is activated. In some cases, it becomes particularly large.

A combinatorial bidirectional address and data bus is provided for internal communication between the individual computers and the variable memory available to all computers, which bus is distinct from the internal address and data bus of each individual computer. All computers are assigned this function by unrelated, software-defined terminals.

This data communication is extremely slow compared to the data transfer to the address/data bus of the computer, so failures are rare. Any errors, such as short circuits, interruptions, or memory defects, can be automatically detected since the data in the memory as well as any data transfers are protected in a well-known manner.

In the variable memory, specific values are stored, for example, in order to adapt the control device to a given engine or to a given vehicle, so that the control device can be quickly adapted, for example, to other engine types. .

If an edge-triggered address memory is connected between the variable memory and the combinational address/data bus, the probability that a faulting edge will coincide with a scanning pulse edge is extremely small, so it is unlikely that the program will be interrupted via the port. It becomes impossible.

Furthermore, due to the number of address bits, it is desirable to provide a control line between the (first) microcomputer and the variable memory. The variable memory can thus be accessed by the first microcomputer, which is useful since the first microcomputer must take over important control tasks and carry out external communications.

In order to be able to control the computers on the other side and quickly eliminate malfunctions in the communication between the individual computers, one or several of the microcomputers are equipped with a restart output, so that they Advantageously, it is connected to an unmasked interrupt input of the microcomputer.

If your computer encounters an error in this way,
It does not return to the initial state as in the case of "Reset". This would thus also lead to a reset, eg the entire peripheral device, which would require a further long recovery time of the computer, which would be unbearable in the case of real-time applications (motorized vehicles), for example.

The invention will be explained in more detail below on the basis of exemplary embodiments shown in the drawings together with other advantages and features.

The drawing shows a block diagram of the microcomputer system of the present invention.

In the embodiment shown in the drawings, three microcomputers 1.
2.3 is shown, but a fourth microcomputer may also exist, for example.

A software-wired combinatorial bidirectional address and data bus exists for communicating data between the individual microcomputers, and the bus has a number of control lines and is connected to the terminals of the individual microcomputers. The control lines take over functions such as busy, request/ready, output enable, etc. Data communication takes place via bus 4 and is extremely slow compared to data communication on the address and data buses of individual microcomputers. Because the speed is slow, safety against failure will be decisively increased.

The native data bus is limited to a 2.3 tm" chip angle and is fault-proof. All inputs and outputs run through ports that are only relatively rarely called upon by the program.

In this case, the response is generated internally by the clock pulse of the D-flip-flop, and the 8) 1J flip-flop receives and receives data only during the duration of the edge of the clock pulse. The probability that an edge of a fault coincides with a scanning pulse is extremely small in this case.

Nevertheless, even if this happens, the probability of its repetition is extremely small. In this case, the program via the terminal (boat) is not subject to any failures. Therefore, if care is taken to protect data, accidental data failures can be detected and rendered harmless.

A variable memory 5 is provided for storing data relating to special applications, for example the engine or the vehicle, to which an address memory 6 is connected in series. Although variable memory is available to all computers via the bus, the first computer 1 is preferred because this computer 1
The computer also performs important control tasks and external communications, as will be explained in more detail below.

First via bus 4, e.g.
, ”, words are retrieved. This word then reaches the address memory (octal lunch), which then places these values at the address inputs of memory 5. Bus 4 is then switched to input, and then The memory is activated by applying the supply voltage and applying the input "output enable" oe.

Here, in order to reduce the heating of the memory module and increase its reliability, the supply voltage is applied to the variable memory (PPOM) via a transistor circuit (not shown) only during readout.
(preferably) is applied.

The memory 5 is thus switched to the bus 4 and finally the microcomputer reads the bus. The above three address bits must be applied via the microcomputer 1's own control lines. That is, the remaining microcomputers 2.3 must establish communication with the first microcomputer 1 only if they wish to interrogate the memory 5.

For example, if a RAM is present in the memory, the microcomputer 1 can also write into the memory, and it can transmit its stored contents outwardly via external communication. The data is protected by well-known methods so that errors due to disconnections, short circuits, faults, etc. can be identified. As a result, the control device can be prevented from operating due to erroneous data that could lead to engine failure or serious accidents.

It is also important that the individual tasks of the microcomputer system are assigned to individual microcomputers. With several microcomputers operating in parallel, incomparably higher performance can be achieved than with individual large microcomputers. - In each microcomputer, the tasks assigned to this computer are executed one after another.

When controlling an engine, i.e. in the case of real-time tasks, events must be processed quickly and certain signals, such as control signals for a diesel engine tuning rond, must be transmitted quickly; Interruption (interruption) when using one microcomputer
This means that priorities are constantly changing and work in progress must be interrupted by nesting other tasks.

However, by using several automatic microcomputers, they can work simultaneously without any hindrance and can easily concentrate on real-time tasks.

In the case of the computer system according to the invention, for example, the microcomputer 1 can be given the following tasks: i.e. control, reception of signals from pressure sensors, temperature sensors, accelerator pedal sensors, masking of external communication,
Direct access to programm memory. Furthermore, the microcomputer can also take over the collection of exhaust gases from internal combustion engines.

The microcomputer 2 is used, for example, to control a stepping motor for an injection pump, to control a stepping motor response synchronizer and process its signals, to measure rotational speed,
It can be installed for control inputs as well as control lamps.

Other tasks can be assigned to microcomputer 3 and possibly a fourth microcomputer. At the start of the drive, it is queried how many individual computers have to respond in this case.

The entire system is then formed.

By assigning tasks, it is also possible to control other controls, for example actuating valves to change the fuel injection timing or regulating exhaust gas recirculation valves, without affecting the rest of the control system. To do this, all you need to do is change the corresponding microcomputer program and replace the connected hardware. In this way, specific user wishes can be met and software expenditures can be limited.

Allocating tasks to different one-chip microcomputers makes it cost-effective to perform other functions of the control system that were traditionally handled by side devices, such as automatic switching being controlled by the onboard computer. This is a prerequisite for

Furthermore, since it is completely unnecessary to connect a further microcomputer to the internal bus 4 unless necessary, access to all sensor data and control data is possible, allowing the control device to be programmed, for example, to set the maximum rotational speed. Commands can be directly issued, and large costs for external monitor communication can be omitted.

Bidirectional control of the microprocessor is possible regardless of assigned tasks. Internal data communication progresses intensively, is maintained intensively by software, and falls within milliseconds when the microcomputer is not operating in an orderly manner.

As shown in the circuit diagram, bidirectional synchronization of the two microcomputers is achieved by connecting the restart output of microcomputer I to the unmasked interrupt input of the other microcomputer. be able to.

If a microcomputer is no longer working fault-free, a restart command is applied to the ]i input via the other microcomputers, setting the program to its initial address. This word has been tried several times.

If it is not possible to convert a faulty microcomputer into the correct working state in this way, the control device can enter an emergency state or carry out an emergency shutdown.

[Brief explanation of drawings]

FIG. 1 is a microcomputer circuit diagram of the present invention. 1.2.3...Microcomputer, 4...
...Address/data bus, 5...Variable memory, 6...Address memory.

Claims (4)

[Claims] (1) A microcomputer installed in an internal combustion engine control device for controlling and adjusting fuel injection and other functions in a motor vehicle according to work values such as rotational speed, load pressure, and accelerator pedal position determined by sensors. In the system, a signal line is connected to the microcomputer system, an output part of the system is connected to an operation part, a signal display part, etc. via a control circuit as the case may be, and the microcomputer system includes at least two microcomputers. In this case, tasks are assigned to individual microcomputers and are configured as plug-in modules together with the individual microcomputers (1, 2, 3), for example in those provided with a variable memory for engine and vehicle data. A variable memory (5) is connected to a combined bidirectional address/data bus (4), which bus (4) is exclusively for exchanging data independently of the address/data bus inside the microcomputer. The system characterized in that: (2) An edge-triggered address memory (6) is connected between the variable memory (5) and the associated address/data bus (4). microcomputer system. (3) A control line is provided between one (first) microcomputer (1) and the variable memory (5) for the number of address bits; The microcomputer system according to item 2. (4) One or more of the microcomputers (1, 2) is equipped with a restart output (re), the output of which is not masked in each case on the other microcomputers (
2. The microcomputer system according to any one of claims 1 to 3, wherein the microcomputer system is connected to the interrupt input unit (@nmi@) of 2.1).