JP2597729B2 - Microcomputer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microcomputer that operates various external circuits based on output data from an output device.

[Conventional technology]

FIG. 3 is a block diagram showing an input / output function of a conventional microcomputer. In the figure, reference numeral 1 denotes a central processing unit (hereinafter abbreviated as CPU) and 2 denotes an output device (hereinafter referred to as a port). The block is connected to the CPU 1 via an address bus 3 and a data bus 4. Reference numeral 5 denotes a peripheral circuit, which indicates several peripheral functions such as a timer, a serial I / O, and an A / D converter.

Next, the operation when output is performed via a port will be described. The port output is determined by the settings of the port input / output direction register and the port data register. The CPU 1 sets an output direction register and a data register in the port 2 via the buses 3 and 4. The output data of the port is switched at the timing of writing from the CPU. The port input / output direction register is for switching the data input / output direction, and the data register is for setting data for controlling an external circuit.

[Problems to be solved by the invention]

Since the port output function of the conventional microcomputer is configured as described above, the output data of the port can be switched only by the CPU, so the CPU always operates and monitors other peripheral functions while the port operates. It bears the burden of performing output setting processing. Further, when the port output is switched at the end of the operation of a certain peripheral function, there is a problem that it takes a considerable time to complete the process of switching the output data of the port after detecting the end of the operation.

The present invention has been made in order to solve such a problem, and it is not necessary for the CPU to start and stop the timing of switching the output data of the port, and the microcomputer can also eliminate the delay time of switching the output data of the port. The purpose is to provide.

[Means for solving the problem]

A microcomputer according to the present invention includes a central processing unit, a peripheral circuit having first and second timers whose start of counting is controlled by the central processing unit, and data set from the central processing unit. Output device, a first holding circuit for holding polarity setting data from the central processing unit, and a polarity setting output from the first holding circuit in response to a control signal from the second timer. A gate circuit for controlling the transmission of data, a second holding circuit for maintaining or inverting the set polarity according to a control signal from the first timer after an output polarity is set by an output of the gate circuit; After the central processing unit sets the output data, the content of the data to be output to the outside can be set to an arbitrary value independently of the control of the central processing unit. It is obtained so as to comprise a switching means for switching in ring.

[Action]

In the present invention, since the configuration is as described above, the CPU
Once the initial value of the port output data is set, the port output is switched by the activation of other peripheral functions independently of the control of the CPU. The port output can be inverted only by the signal generated.

〔Example〕

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

FIG. 1 is a diagram showing a configuration of a microcomputer according to one embodiment of the present invention, in which 1 is a CPU, 2 is a port output circuit (input / output circuit) similar to the conventional example, A second output control circuit 6 operated by a control signal from the peripheral circuit 5 is added to this, and the output of the second output control circuit 6 and the output of the port output circuit 2 are switched by switches 9a and 9b controlled by the CPU 1 to one of them. Is configured to be selectable.

FIG. 2 is a configuration example of a second output control circuit. Here, control signals are received from two timers A and B as peripheral circuits, and the polarity of the output of the port control circuit 2 (HIGH) is thereby obtained.
/ LOW) will be described as an example.

First, the CPU 1 sets data in the polarity setting buffer 8 via the buses 3 and 4, and instructs the timers A and B to start counting. When the timer B issues the control signal, the initial data is set in the toggle flip-flop 7, and thereafter, whenever the timer A issues the control signal, the polarity of the output Q of the toggle flip-flop is inverted. Therefore, the port output can respond to the control signal from the timer A in real time independently of the CPU and switch the polarity.

As described above, according to this embodiment, the CPU does not need to start and stop the output data switching timing of the port,
In addition, since the port output is switched in real time to the operation of the peripheral circuit even when the port output is switched, it is possible to control the external circuit (for example, a motor drive control circuit) with simpler software processing and with higher accuracy. The effect is obtained.

The timer A starts counting when the timer B overflows, the control signal for the timer B is issued when the timer B overflows, and the control signal for the timer A is timer A
In the configuration in which the count start of the timer is caused by both overflows, the microcomputer has an excellent effect on sine wave formation by appropriately changing the count values of the timers A and B, and can be operated independently. 2
By providing three output control circuits, it can be effectively used as a control device for an inverter motor.

Further, in the above embodiment, two timers A and B are taken as an example of the control signal source, but the control signal is not limited to this, and a signal of another peripheral function may be used.
The same effects as in the above embodiment can be obtained.

〔The invention's effect〕

As described above, according to the microcomputer of the present invention, the central processing unit, the peripheral circuit having the first and second timers whose start of counting is controlled by the central processing unit, and the central processing unit An output device for outputting data set from the processing device, a first holding circuit for holding polarity setting data from the central processing unit,
A gate circuit for controlling transmission of the polarity setting data output from the first holding circuit in response to a control signal from the second timer, and after the output polarity is set by the output of the gate circuit, the first circuit A second holding circuit in which the set polarity is maintained or inverted in accordance with a control signal from the timer of the above. After the central processing unit sets output data, the control of the central processing unit Independently,
By providing switching means for switching the content of data to be output to the outside at an arbitrary timing, port output switching can be controlled by a signal generated by a peripheral circuit without passing through the CPU. After setting the peripheral circuit and sending a peripheral circuit operation start command, there is no need to perform peripheral circuit operation, monitoring, or port output control processing. This time can be used for other calculations and data processing. This has the effect of improving the processing efficiency of the CPU.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a microcomputer according to the present invention, FIG. 2 is a diagram showing an embodiment of a microcomputer according to the present invention, and FIG. 3 is a block diagram showing a configuration of a conventional microcomputer. . In the figure, 1 is a CPU, 2 is an input / output circuit, 3 is an address bus, 4 is a data bus, 5 is a peripheral circuit, 6 is a second output control circuit, 7 is a toggle flip-flop, and 8 is an output data setting buffer. . In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] A central processing unit; a peripheral circuit having first and second timers whose start of counting is controlled by the central processing unit; and outputting data set from the central processing unit. An output device; a first holding circuit for holding polarity setting data from the central processing unit; and transmission of polarity setting data output from the first holding circuit in response to a control signal from the second timer. And a second holding circuit for maintaining or inverting the set polarity according to a control signal from the first timer after the output polarity is set by the output of the gate circuit. A switching means for switching the content of data to be output to the outside at an arbitrary timing independently of the control of the central processing unit after the central processing unit sets the output data; Microcomputer comprising the.