JPH031284A - Constant setting device of microcomputer - Google Patents

Abstract

PURPOSE:To constitute the device so that even if a control constant to be set increases, the number of necessary input terminals does not increase by setting the control constant in a microcomputer, based on an oscillating signal whose oscillation frequency is variable. CONSTITUTION:A combined resistance R0 between both ends of resistances R6-R8 connected in series can be set by connecting jumper wires J6-J8, therefore, by connecting the jumper wires J6-J8 determined in advance, an oscillation frequency of an oscillating signal from an oscillating circuit 12 can be varied. The oscillating circuit 12 applies an oscillating signal having a set oscillation frequency to an input terminal 15 provided on a microcomputer 11. The micro computer 11 excutes an operation, based on a control constant corresponding to a frequency of a signal applied to the input terminal 15. In such a way, by varying the oscillation frequency of a frequency signal from the oscillating circuit 12, the control constant which is set in the microcomputer 11 is varied, therefore, the number of input terminals 15 can be saved to the minimum.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a constant setting device for a microcomputer that sets a constant (hereinafter referred to as "control constant j") indicating a control mode to be controlled by a microcomputer in a microcomputer.

BACKGROUND ART An engine control device that controls fuel injection of an internal combustion engine is equipped with a microcomputer, and the fuel injection time, rotational speed of the internal combustion engine, etc. are determined based on control constants set in the microcomputer. and engine control is performed.

The engine control device is generally constructed by mounting a microcomputer and other electronic components on a wiring board on which the same circuit structure is printed regardless of the type of vehicle.

However, -a, since the engine control differs depending on the car model, the control constants set in the microcomputer that performs the engine control are configured differently for each car model. If the control constants were set and fixed, the microcomputers installed in the engine control bag would be different for different car models, and the same microcomputer could not be shared between different car models. .

Therefore, conventionally, the microcomputer stores a plurality of control constants to be selected in memory regardless of the vehicle type, and by switching the signal applied to the input terminal of the microcomputer for each vehicle type, each control constant is stored in memory. It is configured so that control constants specific to the vehicle type are set in the microcomputer. With the above configuration, the same microcomputer can be installed regardless of the vehicle type, and the workability of the manufacturing process of the engine control device is improved.

FIG. 4 is a block diagram showing a simplified configuration of the conventional constant setting device 1. As shown in FIG. The constant setting device 1 includes a microcomputer 2 and a resistor and wiring line for setting control constants in the microcomputer. Based on control constants set in the microcomputer 2, fuel injection control of the internal combustion engine 3, etc., is performed, for example.

The microcomputer 2 receives the supplied driving voltage Vcc.
Driven by. Among the input/output terminals of the microcomputer 2, constant setting terminals ADJ1. ADJ2 is connected to the drive voltage Vec line via resistors R1 and R2, respectively. In addition, the terminal ADJI AD
Each J2 has a terminal Jll for connecting a jumper wire.
, J21 are connected. Further, the microcomputer 2 is connected to a ground potential Vss which is a reference potential. The terminals are formed on the wiring board so that jumper wires Jl and J2 can be connected between opposing terminals of the terminals J12 and J22 connected to the ground potential Vss and the terminals Jll and J21, respectively. .

With the above configuration, a high/low level signal is input to the constant setting terminal ADJI based on the presence or absence of the 5 jumper MJI, and similarly, a high/low level signal is input to the constant setting terminal ADJ2 based on the presence or absence of the jumper J2. A level signal is input. That is, the constant setting terminal ADJI, A
Since it is possible to input two types of level signals to each DJ2, a total of four combinations of signals can be input to the jumper wire Jl.
, J2.

Therefore, four types of control constants can be set in the microcomputer 2. That is, by storing four types of control constants in a memory (not shown) in the microcomputer 2 and determining the connection of jumper wires Jl and J2 based on each vehicle type, constant setting terminals ADJI and AD
Control constants are designated from within the memory in response to the input signal to J2, and it is possible to set a control constant specific to each vehicle type.

Problems to be Solved by the Invention In the constant setting device 1 described above, the constant setting terminal AD
Only two types of signals, high level or low level, can be input to JI and ADJ2, respectively. Therefore, in the conventional example, four types of constants are assumed, so the number of terminals can be sufficient as two. However, in order to set a larger number of control constants, more terminals are required. However, in a microcomputer, it is necessary to secure input/output terminals for multiple other control signals.
It is possible to increase the number of constant setting terminals.

This results in an insufficient number of terminals for inputting/outputting other control signals, which is not practical.

An object of the present invention is to solve the above-mentioned problems, and to provide a constant setting device for a microcomputer that can set a plurality of control constants using one input terminal.

Means for Solving the Problems The present invention provides a microcomputer that has an input terminal and performs calculations using a control constant that corresponds to the frequency of a signal applied to the input terminal; A constant setting device for a microcomputer, characterized in that it includes an oscillation circuit applied to a terminal, and means for setting an oscillation frequency of the oscillation circuit.

Function: According to the microcomputer setting constant device of the present invention, the oscillation frequency of the oscillation circuit is set by the means for setting the oscillation frequency. The oscillation circuit provides an oscillation signal having a set oscillation frequency to an input terminal I\ of the microcomputer. The microcomputer performs calculations based on a constant that corresponds to the frequency of the signal applied to the input terminal.

Therefore, by changing the oscillation frequency of the frequency signal from the oscillation circuit, the control constants set in the microcomputer are changed, so the number of input terminals can be minimized.

Embodiment FIG. 1 is a block diagram showing a simplified configuration of a constant setting device 10 which is an embodiment of the present invention.

The constant setting device 10 includes a microcomputer 11 and an oscillation circuit 12 that provides an oscillation signal whose frequency is variable to the microcomputer 11.

The microcomputer 11 is driven by being supplied with a drive voltage Vcc, and performs, for example, fuel injection control of the internal combustion engine 13 based on control constants set as described below.The reference potential of the microcomputer 11 is The ground potential is Vss.

The oscillation circuit 12 is a comparator circuit 1 such as an operational lamp, for example.
4 and resistors R3 to R arranged around the comparison circuit 171.
8 and a capacitor CI. The positive input terminal of the comparison circuit 14 is connected to the connection point of resistors R3 and R4 connected in series from the line of the drive voltage Vcc to the ground potential, and further connected to the positive input terminal of the comparison circuit 14 via a positive feedback resistor R5. It is connected to the output terminal of circuit 14. On the other hand, the negative input terminal of the comparator circuit 14 is connected to the ground potential via the capacitor C1, and the resistors R6 to R6 are connected in series.
It is connected to the output terminal of the comparison circuit 14 via R8.

Terminals JOI to JO4 for connecting jumper wires J6 to J8 that short-circuit both ends of each resistor are connected to each end of each of the resistors R6 to R8 connected in series, respectively,
Each of the terminals Jot to JO4 is formed on a wiring board on which the oscillation circuit 12 is constructed so that jumper wires J6 to J8 can be connected thereto. Therefore, the terminal JOI
~ Jumper wire J6 between the predetermined terminals of J04 ~
By connecting J8, the resistor R connected in series
The self-resistance of 6 to R8 changes.

The comparison circuit 14 outputs a high level or low level signal from its output terminal based on a comparison between the voltage level of the positive input terminal and the voltage level of the negative input terminal. That is,
When the potential difference Vc applied across the capacitor C is smaller than the reference voltage Vref determined by the resistors R3 and R4, the comparator circuit 14 outputs a high level, and the capacitor C is outputted via the resistors R6 to R8 connected in series. Along with the charging, the potential difference Vc of the capacitor C
becomes equal to or higher than the reference voltage Vref, the comparison circuit 1
4 outputs a low level, and discharge is performed from the capacitor C via resistors R6 to R8 connected in series. At t&, when the potential difference Vc of the capacitor C becomes less than the reference voltage Vref again, the comparison circuit 14 outputs a high level.

The period T of the high/low level switching timing of the comparison circuit 14 is determined by the capacitance CIO of the capacitor C1 and the resistors R6 to R.
It can be varied according to the time constant determined by the resistance values R'60 to R80 of 8. That is, since the combined resistance RO between both ends of the resistors R6 to R8 connected in series can be set by connecting the jumper wires J6 to J8 as described above, the resistance from the oscillation circuit 12 can be set by connecting the jumper wires determined in advance. The oscillation frequency I of the oscillation signal is the first
It can be changed to satisfy the relationship in the equation.

(A4. is a constant determined by the resistors IIaR30 to R50, and ROO is the resistance value of the combined resistor RO.) Table 1 shows the oscillation frequency I of the oscillation circuit 12 and the presence or absence of connection of the jumper wires J6 to J8. This is a table showing the relationship between In addition,
It is assumed that the magnitude relationship between the resistance values R60 to R80 of the resistors R6 to R8 satisfies the relationship of the second equation.

R60> R70+ R80>R70> R80...
・(2) (blank below) Indicates that the first line is shown, and the × indicates that the corresponding jumper wire is not connected. ) As shown in Table 1, seven oscillation frequencies 1 can be set by combining the connections of jumper wires J6 to J8.

An oscillation signal from the oscillation circuit 12 whose oscillation frequency has been set as described above is applied to an input terminal 15 called a capture input terminal provided in the microcomputer 11. The set period T of the oscillation signal applied to the input terminal 15 is detected by the processing circuit 16.

FIG. 2 is a timing chart showing the oscillation signal O8C from the oscillation circuit 12. In the processing circuit 16, the oscillation signal O from the oscillation circuit 12 applied to the input terminal 15/\
Detect the rising timing of 8C. That is, the second
In the figure, the oscillation signal O8C applied to the input terminal 15
A first rising timing t1 and a second rising timing t2 following the first rising timing t1 are detected, and a circuit (not shown) in the processing circuit 16 calculates the rising timing based on the respective rising timings tl and t2. The time in between, that is, the period T of the oscillation signal O8C is detected.

A memory 17 is provided in advance in the processing circuit 16,
In the memory, there are specific IIJI settings that are set for each vehicle type.
A plurality of I constants are stored. The processing circuit 16 reads out the corresponding control constant from the memory 17 using the detected cycle T as an address signal, and sets it in the microcomputer 11. In the microcomputer 11, for example, the fuel injection time, the rotational speed of the internal combustion engine, etc. in the fuel injection control of the internal combustion engine 13 are set based on the set control constants.

In the oscillation circuit 2812 in FIG.
Seven types of oscillation frequencies f can be set as shown in Table 1 by combinations of connections of J8, so seven types of control n constants A-a (see Table 1) are stored in the memory 17. To set , the corresponding control constants can be read out from the memory 17 in accordance with each oscillation frequency f (period T) predetermined in the oscillation circuit 12 and set in the microcomputer 11 using L. .

FIG. 3 is a flowchart for explaining the control constant setting operation. The program shown in FIG. 3 starts when the oscillation signal O8C from the input Qi t' 151\oscillation circuit 12 in the microcomputer 11 is applied.

In step s1, the first rising-E retiming L1 and the second rising timing L2 of the input oscillation signal O8C are detected, and in step s2, the period T of the oscillation signal O8C is determined from the timing tl and 02. is detected, and the process proceeds to step s3'\.

In step s3, the corresponding limiting constant is read out from the memory 17 using the detected period T as an address signal,
It is set in the microcomputer 11. At step S4, the fuel injection time and rotational speed of the internal combustion engine are set, the internal combustion engine is controlled, and the program ends.

As described above, according to this embodiment, a control constant can be set in the microcomputer based on the oscillation frequency of the oscillation signal from the oscillation circuit, and furthermore, the oscillation frequency can be set on the wiring board on which the oscillation circuit is configured. This is done by connecting jumper wires on top. Therefore, in order to set the control constants in the microcomputer, it is sufficient to provide one input terminal for inputting the oscillation signal from the oscillation circuit, and the number of terminals of the microcomputer required for setting the control constants is limited. can be saved to a minimum.

In this embodiment, the rising timing of the oscillation signal is detected in order to detect the period of the oscillation signal in the processing circuit, but the processing circuit may be configured to detect the falling timing.

The rising or falling timing can be set by a program within the processing circuit.

Furthermore, although this embodiment describes a microcomputer that controls the fuel injection of an internal combustion engine, this is not a limitation; for example, in a radio receiver, the inter-office frequency of each receiving frequency band is The configuration may be such that the setting is performed using control constants within the microcomputer.

Further, in this embodiment, although the oscillation signal of the oscillation circuit whose oscillation frequency can be varied by connecting jumper wires is input to the microcomputer, this is not a limitation; for example, Even in the case of an oscillation circuit that outputs an oscillation signal having a unique oscillation frequency, the oscillation signal is supplied to the microcomputer via a frequency divider circuit, and the frequency division ratio of the frequency divider circuit is changed. may be configured.

Effects of the Invention According to the present invention, since control constants are set in a microcomputer based on an oscillation signal with a variable oscillation frequency, the number of input terminals required for setting control constants in the microcomputer can be minimized. You can save as much as possible. Therefore, even if the number of control constants to be set increases, the number of required input terminals does not increase, and this does not cause a shortage of terminals for other signals.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a simplified configuration of a constant setting device 10 which is an embodiment of the present invention, and FIG. 2 is a block diagram showing the oscillation circuit 12.
Timing chart showing the oscillation signal O8C from the third
The figure is a flowchart for explaining the control constant setting operation, and FIG. 4 is a block diagram showing a simplified configuration of the conventional constant setting device 1. DESCRIPTION OF SYMBOLS 10... Constant setting device, 11... Microcomputer, 12... Oscillation circuit, 13... Internal combustion engine, 14
...Comparison circuit, 15..Input terminal, 16..Processing circuit, 17.Memory, CI...Capacitor, f...Oscillation frequency, Jot~JO4...Connection terminal, J6~J8
...Jumper wire, R3-R8...Resistance, T...Period, tl, L2...Rise timing, Vcc...Drive voltage, Vss/Ground potential agent Patent attorney Kei Saikyo Figure 1/ 10 Figure 2

Claims (1)

[Scope of Claims] A microcomputer that has an input terminal and performs calculations using a control constant corresponding to the frequency of a signal applied to the input terminal, and an oscillation circuit that applies an oscillation signal with a variable frequency to the input terminal. A constant setting device for a microcomputer, comprising: a means for setting an oscillation frequency of the oscillation circuit.