Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication
Reexamination Certificate
2002-11-20
2004-03-16
Nguyen, Thu V. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Reexamination Certificate
active
06708089
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an on-vehicle electronic controller incorporating a microprocessor used for controlling fuel supply of a vehicle engine and so on. The invention particularly relates to an on-vehicle electronic controller that is improved in handling a large number of input/output signals and in standardizing the controller regarding the control on various types of vehicles.
2. Description of the Related Art
FIG. 9
is a typical general block circuit diagram showing one of conventional on-vehicle electronic controllers of this type. An ECU (engine control unit)
1
comprised of a single printed circuit board includes a LSI (integrated circuit)
2
as a main component. In the LSI
2
, a CPU (microprocessor)
3
, a nonvolatile flash memory
4
, a RAM memory
5
, an input data selector
6
, an A/D converter
7
, an output latch memory
8
and so on are connected via a data bus
30
. The ECU
1
operates in response to a control power supplied from a power supply unit
9
, which is fed from an on-vehicle battery
10
via a power supply line
11
and a power switch
12
. An execution program, a control constant for controlling an engine, and so on are stored in the nonvolatile flash memory
4
in advance.
Meanwhile, a large number of ON/OFF input signals from various sensor switches
13
are supplied from a bleeder resistors
14
serving as a pull-up or pull-down resistance, to comparators
19
via series resistors
15
and parallel capacitors
16
that constitutes a noise filter. Input resistors
17
and reaction resistors
18
are connected to the comparator
19
. When a voltage across the parallel capacitors
16
exceeds a reference voltage applied to a negative terminal of the comparator
19
, a signal of logic ‘H’ is supplied to the data selector
6
. However, when decreasing the voltage across the parallel capacitors
16
, the input from the reaction resistor
18
is added thereto. Therefore, the output of the comparator
19
returns to logic ‘L’ since the voltage further decreases to less than the reference voltage. As described above, the comparator
19
acts as a level judging comparator including a hysteresis function, and a large number of outputs from the comparators
19
are stored in the RAM memory
5
via the data selector
6
and the data bus
30
.
In addition, for example, the mentioned data selector
6
handles an input of 16 bits and outputs the input to the data bus
30
when receiving a chip select signal from the CPU
3
. Input points range over several tens points, and a plurality of data selectors are used.
Further, a large number of analog signals from various analog sensors
20
are supplied to the A/D converter
7
via series resistors
21
and parallel capacitors
22
that constitute a noise filter. Digital outputs from the A/D converter that receive chip select signals from the CPU
3
are stored in the RAM memory
5
via the data bus
30
. Control outputs from the CPU
3
are stored in the latch memory
8
via the data bus
30
and drive external loads
26
via output transistors
23
. To cope with a large number of control outputs, a plurality of latch memories are used, and the control outputs are stored in the latch memories chip-selected by the CPU
3
.
Reference numeral
24
is driving base resistors of the transistors
23
, numeral
25
is stable resistors connected between base/emitter terminals of the transistors
23
, numeral
27
is an output contact of a feeding power supply relay for the external loads
26
.
The conventional apparatus of above arrangement has problems as follows. The LSI
2
becomes large in size because the CPU
3
handles a large number of inputs and outputs. The parallel capacitors
16
acting as a noise filter require capacitors having a variety of capacities to secure a desired filter constant, thereby causing a difficulty in standardization, and it is necessary to employ a large capacitor to secure a large filter constant, increasing the ECU
1
in size.
As a measure for reducing the input/output terminals of the LSI
2
to miniaturize the LSI
2
, for example, Japanese Patent Laid-Open (unexamined) No. 13912/1995 specification “Input/Output Processing IC” discloses a method of time-sharing and transferring a large number of input/output signals using a serial communication block.
However, this method requires a noise filter of various capacities and is not suitable for standardization of the device. Moreover, a capacitor demands a large capacity to obtain a sufficient filter constant and is not suitable for miniaturization of the device.
Meanwhile, a concept has been publicly known in which a digital filter is used as a noise filter for ON/OFF input signals and the filter constant is controlled by a microprocessor. For example, in “Programmable Controller” disclosed in Japanese Patent Laid-Open (unexamined) No. 119811/1993 specification, when any input logic value of an external input signal subjected to sampling is successively set at the same value for more than one time, the signal is adopted and stored in an input image memory, and a filter constant changing command is provided for changing a sampling period.
In this method, although a filter constant can be freely changed, a microprocessor bears a large burden in handling a large number of input signals, resulting in slower response of control.
As another example of a digital filter for ON/OFF input signals, Japanese Patent Laid-Open (unexamined) No. 89974/2000 specification discloses “Data Storage Control Circuit”, in which a shift register is provided as hardware and sampling is carried out according to the same concept as described above.
As described above, however, the mentioned conventional is partially but is not fully miniaturized and standardized in an integral manner. Particularly, in case of miniaturizing and standardizing an input/output circuit of the microprocessor, it is not possible to avoid reduction in original control capability and response of the microprocessor.
SUMMARY OF THE INVENTION
In order to solve the above-discussed problems, the first object of the present invention is to provide an on-vehicle electronic controller capable of reducing a burden of a microprocessor in processing input and output to improve its original control capability and response and achieving entire miniaturization and standardization of the controller by reducing an input filter in size.
The second object of the invention is to provide an on-vehicle electronic controller capable of changing a control program and a control constant for various types of vehicle each having different control specifications so as to readily standardize the hardware in a more effective manner.
An on-vehicle electronic controller according to the invention includes a microprocessor having a nonvolatile memory, in which a control program for a controlled vehicle and a control constant are written by an external tool, and a RAM memory for computation. The mentioned on-vehicle electronic controller also includes direct input interface circuits and direct output interface circuits that are connected to a data bus of the mentioned microprocessor and handle high-speed inputs and outputs for engine drive control. The mentioned on-vehicle electronic controller further includes a first serial-parallel converter connected to the mentioned microprocessor via a data bus, a second serial-parallel converter serially connected to the mentioned first serial-parallel converter, and a communication control circuit for serial communication connected to the mentioned second serial-parallel converter via a data bus. The mentioned on-vehicle electronic controller further includes an output latch memory for storing control output signals transmitted via the mentioned first/second serial-parallel converter with respect to low-speed output signals of an auxiliary driving output and an alarm display output, and indirect output interface circuits each connected to an output terminal of the mentioned output latch memory. Furthermore, the ment
Hashimoto Kohji
Nakamoto Katsuya
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