JP2017167990A - Function switching device and function switching method of microprocessor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to select a large number of functions by smaller number of signal lines, and suppress power consumption and prevent erroneous setting.SOLUTION: A microprocessor 2 is mounted on a base substrate 1, the microprocessor 2 has a general-purpose output terminal 11 which supplies power source to an attachment substrate 21, and has an A/D converter 7 for identifying voltage input from the attachment substrate 21. The attachment substrate 21 has resistance 22 of a specific fixed resistance value corresponding to one of a plurality of functions. A function of the microprocessor 2 is selected based on a voltage value obtained by the attachment substrate 21 selectively connected via connectors 13, 23.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a function switching device and a function switching method for selecting a function of a microprocessor having a plurality of functions.

  Patent Document 1 discloses an interface device in which the function of an input / output terminal of a serial interface is selectively switched between an SPI interface and an I2C interface. In this system, one of the general-purpose input / output terminals of the microprocessor is used to switch between two functions. In such a system, if the number of functions to be switched increases, it is necessary. The number of signals increases. That is, if there are two types of switching functions, switching can be performed with one signal line. However, two signal lines are required for switching between three to four types of functions, and 5-8. Three signal lines are required for switching between different types of functions.

  In order to realize such switching of a large number of functions with a minimum number of signal lines, Patent Document 2 discloses a technique in which a function is selected by setting a variable resistor. That is, a power source is connected to a variable resistor, a voltage dropped by a variably set variable resistor is input to an A / D converter as a function selection signal, and an analog / digital conversion result is used for the microprocessor. It is configured to select a function.

JP2013-58868A JP 2004-185236 A

  However, the technique of Patent Document 2 has a problem that power is always consumed because the power supply voltage is always input to the variable resistor.

  In addition, a variable resistor whose resistance value changes continuously is used to set the resistance value corresponding to the function by the operator, so an unintended function is executed due to variations in the set resistance value. There is a possibility that.

A function switching device for a microprocessor according to the present invention includes:
A base board having a general-purpose output terminal for supplying a power for generating a function selection signal and an A / D converter for identifying the function selection signal;
An attachment board connected to the general-purpose output terminal and the input terminal of the A / D converter, generating a function selection signal from the power source input from the general-purpose output terminal, and outputting the function selection signal to the input terminal of the A / D converter;
It is configured with.

  In such a configuration, when selecting a function, power is supplied from the general-purpose output terminal of the microprocessor to the attachment board, and in response thereto, a function selection signal is output from the attachment board to the input terminal of the A / D converter. Is done. The microprocessor determines the function requested by the attachment board from the result of A / D conversion of the function selection signal. For example, if it is a 12-bit A / D converter, a maximum of 4095 types of functions can be selected theoretically. On the other hand, the number of signals between the base substrate and the attachment substrate is extremely small (theoretically two). The attachment substrate is prepared as one corresponding to one specific function, and the function is switched by connecting the attachment substrate corresponding to the desired function to the base substrate. Therefore, no different functions are executed by mistake.

  In a preferred aspect of the present invention, the attachment substrate is a resistance substrate having a fixed resistance value corresponding to one of a plurality of functions. That is, the function selection signal is output as a voltage corresponding to the fixed resistance value of each attachment board.

  In a further preferred aspect, the microprocessor uses an A / D conversion value of a voltage input as a function selection signal to an input terminal of the A / D converter corresponding to the fixed resistance value, among a plurality of functions. The table is associated with one of these.

  In one preferred embodiment of the present invention, the attachment board is detachably attached to the base board via a connector. Thus, the function can be selected by simply attaching and detaching the attachment substrate.

  In the present invention, preferably, power is supplied from the general-purpose output terminal to the attachment board only when a function is selected. This minimizes the power consumption required for function selection.

The microprocessor function switching method according to the present invention includes:
An attachment substrate having a fixed resistor corresponding to one of a plurality of functions is selectively connected to a base substrate on which a microprocessor having an A / D converter is mounted;
Supply power from the general-purpose output terminal of the microprocessor to the attachment board,
The function selection signal output from the attachment board by the power supply is A / D converted by the A / D converter,
This A / D conversion value is associated with one of a plurality of functions, and the function is selected.

  According to the microprocessor function switching device and the function switching method according to the present invention, a large number of functions can be selected with a small number of signals. Since power is supplied from the general-purpose output terminal of the microprocessor to the attachment board prepared for each function, for example, power can be supplied only at the time of function selection, and power consumption associated with function selection is reduced. In addition to being able to suppress, it does not accidentally execute different functions.

Explanatory drawing which showed the structure of the base substrate of one Example. Explanatory drawing which showed the structure of the attachment board | substrate of one Example. Explanatory drawing of the state which connected the attachment board | substrate to the base board | substrate.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a base substrate 1 on which a microprocessor 2 capable of executing a plurality of functions is mounted. The microprocessor 2 is configured as one semiconductor device, and includes an arithmetic processing unit 3, a ROM 4, a RAM 5, an input / output unit 6, an A / D converter 7, a D / A converter 8, and the like. Here, a plurality of software (programs) are stored in advance in the ROM 4 as a plurality of functions, and the microprocessor 2 reads out the software corresponding to the selected function from the ROM 4 and loads it into the RAM 5. It is supposed to run. The base substrate 1 includes a power supply unit 9 that supplies power to the microprocessor 2. The selection of “function” in the present invention includes various types, for example, switching of operating system, switching of application software, switching of the type of interface connected to an external device, and microprocessor 2 are incorporated. Widely includes switching of operation modes of embedded devices.

  The input / output unit 6 includes a plurality of general-purpose output terminals, and one of the general-purpose output terminals 11 is configured to be able to supply power for generating a function selection signal. The A / D converter 7 includes an input terminal 12. A connector 13 of an appropriate type is mounted on the base substrate 1, and the general-purpose output terminal 11 and the input terminal 12 of the A / D converter 7 are connected to respective connection terminals (not shown) provided on the connector 13. Connected). In the present embodiment, the connector 13 may be a two-terminal connector.

  FIG. 2 shows an attachment board 21 used for function selection of the microprocessor 2. The attachment board 21 is formed of a resistance board in which a resistor 22 having a predetermined fixed resistance value is formed by printing a resistor, for example, and a connector 23 having two connection terminals (not shown) connected to both ends of the resistor 22 is provided. Has been implemented.

  The resistance value of the resistor 22 corresponds to one of a plurality of functions. In other words, an attachment substrate 21 having a specific resistance value is prepared as one corresponding to each of a plurality of functions. As an example, if the microprocessor 2 of the base substrate 1 is switchable to 16 functions, 16 types of attachment substrates 21 having different resistance values are prepared.

  As shown in FIG. 3, the attachment board 21 configured as one corresponding to one of a plurality of functions selects a specific one corresponding to a desired function, and as shown in FIG. It is used by being connected to the base substrate 1 through 23. In this state where the attachment substrate 21 is connected to the base substrate 1, the general-purpose output terminal 11 of the microprocessor 2 is connected to one end of the resistor 22, and the input terminal 12 of the A / D converter 7 is connected to the other end of the resistor 22. Is done. In FIG. 3, the connector 13 on the base substrate 1 side and the connector 23 on the attachment substrate 21 side are illustrated as being connected by two signal lines 25 and 26. 23 may be physically coupled directly to each other, or both may be connected via cables corresponding to the signal lines 25 and 26.

  The function selection using the attachment board 21 is performed by supplying power from the microprocessor 2 side to the attachment board 21 via the general-purpose output terminal 11 and selecting the voltage dropped by the resistor 22 at the time of function selection using some signal as a trigger. This is done by reading through the input terminal 12 of the / D converter 7. The function selection is performed, for example, when the microprocessor 2 is initially turned on or reset, when the connection of the attachment board 21 to the base board 1 is detected by some means, or by the operator's manual operation. It can be configured to perform at an appropriate timing such as when requested.

  The attachment substrate 21 may be always connected to the base substrate 1 or may be configured to be connected to the base substrate 1 only when a function is selected.

  A voltage input as a function selection signal to the input terminal 12 of the A / D converter 7 in response to power supply from the general-purpose output terminal 11 is converted into a digital value by the A / D converter 7 on the microprocessor 2 side. And the function corresponding to the attachment board | substrate 21 is detected based on this digital value.

  In one example, a 12-bit A / D converter is used as the A / D converter 7 and a digital value of 0 to 4095 can be output in accordance with a voltage change. However, the resistance of the resistor 22 formed on the attachment substrate 21 In consideration of some variation in the values, as shown in Table 1 below, the digital values are divided into 16 patterns with appropriate widths. The resistance values of the 16 types of attachment substrates 21 are set so that voltage values are obtained in the vicinity of the median value in the range of the upper and lower limits of the 16 digital values in Table 1.

  The correspondence relationship between the digital value (A / D conversion value) and the function shown in Table 1 is stored in advance in the ROM 4 of the microprocessor 2 as a table. Therefore, the microprocessor 2 refers to the A / D conversion value of the voltage obtained through the A / D converter 7 at the time of selecting the function with the table in the ROM 4 and classifies it as one of the identification results of “0 to 15”. , Select each corresponding function. For example, if the A / D conversion value is “272”, the identification result is “1”, and the second function is executed. That is, software corresponding to the second function is read, and the microprocessor 2 operates in accordance with the software. If the A / D conversion value is “3830”, the identification result is “14”, and the fifteenth function is executed. That is, software corresponding to the fifteenth function is read, and the microprocessor 2 operates along with this.

  Note that the above “16 types” of function numbers is merely an example, and it is possible to switch to a larger number of functions. Even if the number of functions to be switched increases, the number of signals between the base substrate 1 and the attachment substrate 21 is basically two signal lines 25 and 26.

  Thus, according to the configuration of the above embodiment, it is possible to switch a large number of functions with a small number of signals. Since the function is selected by selectively attaching the attachment substrate 21 having a fixed resistance value corresponding to each function to the base substrate 1, a setting error is caused as in the case of using a conventional variable resistor. Therefore, there is no problem that an unintended function is selected. In particular, in the above embodiment, since the attachment substrate 21 can be easily attached and detached via the connectors 13 and 23, the function can be selected easily and reliably. In addition, since power is supplied to the attachment substrate 21 via the general-purpose output terminal 11 of the microprocessor 2, it is easy to supply power only when selecting a function, and avoid constant power consumption for function selection. Can do.

DESCRIPTION OF SYMBOLS 1 ... Base board 2 ... Microprocessor 6 ... Input-output part 7 ... A / D converter 11 ... General-purpose output terminal 12 ... Input terminal 13 ... Connector 21 ... Attachment board 22 ... Resistance 23 ... Connector

Claims (6)

A base board having a general-purpose output terminal for supplying a power for generating a function selection signal and an A / D converter for identifying the function selection signal;
An attachment board connected to the general-purpose output terminal and the input terminal of the A / D converter, generating a function selection signal from the power source input from the general-purpose output terminal, and outputting the function selection signal to the input terminal of the A / D converter;
A function switching device for a microprocessor comprising:   2. The microprocessor function switching device according to claim 1, wherein the attachment board is formed of a resistance board having a fixed resistance value corresponding to one of a plurality of functions.   The microprocessor is a table for associating an A / D conversion value of a voltage input as a function selection signal to an input terminal of the A / D converter corresponding to the fixed resistance value with one of a plurality of functions. The function switching device for a microprocessor according to claim 2, further comprising:   4. The microprocessor function switching device according to claim 1, wherein the attachment substrate is detachably attached to the base substrate via a connector.   5. The microprocessor function switching device according to claim 1, wherein power is supplied from the general-purpose output terminal to the attachment board only when a function is selected. An attachment substrate having a fixed resistor corresponding to one of a plurality of functions is selectively connected to a base substrate on which a microprocessor having an A / D converter is mounted;
Supply power from the general-purpose output terminal of the microprocessor to the attachment board,
The function selection signal output from the attachment board by the power supply is A / D converted by the A / D converter,
A microprocessor function switching method for selecting a function by associating the A / D conversion value with one of a plurality of functions.

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