JPH083771B2 - Oscillation control device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oscillation control device that can be used for controlling a microprocessor, for example.

2. Description of the Related Art In a system using a plurality of microprocessors, one microprocessor is used for system control in order to control the entire system. This microprocessor is the master and is called the master microprocessor. The remaining microprocessors controlled by this master microprocessor are called slaves and are called slave microprocessors. When controlling the entire system by distributing it to multiple microprocessors, the maximum amount of work that should be controlled by the entire system is assumed and the control is decentralized. The processor may be idle with no work to process. In recent years, in order to reduce the power consumed by the control system, a method of stopping the operation of the slave microprocessor in the idle state and also stopping the oscillation operation is used. When it becomes necessary to control the slave microprocessor in this idle state, the master microprocessor normally restarts the oscillation operation with an interrupt signal, etc. to enable it and control the system. Many. In this case, if the interrupt signal from the master microprocessor is the oscillation operation restart signal for all slave microprocessors, all slave microprocessors restart their operations all at once, and slave microprocessors that do not need to operate also operate. However, it consumes unnecessary power. When the oscillation restart signal for the slave microprocessor is created for each slave microprocessor, the output signals from the master microprocessor must be output individually for each slave microprocessor, and the oscillation operation must be restarted. Therefore, the output terminal of the master microprocessor is wastefully used for the control. In addition to the interrupt signal, serial data is sent from the master microprocessor to the slave microprocessor as a signal for requesting the slave microprocessor to restart the oscillation operation. Some microprocessors restart the oscillation operation, but in this case as well, the slave microprocessor to operate cannot be selected, and all slave processors restart operation.

As described above, when a system is constructed by using a plurality of microprocessors in the related art, in order to control the oscillation restart operation of the slave microprocessor by the master microprocessor, all the oscillations are stopped. In order to restart the slave microprocessors all at once or individually control the restart of oscillation of each slave microprocessor, the output terminals of the master microprocessors have to be individually provided.

The present invention provides a control device capable of receiving serial data output from a master microprocessor even in a slave microprocessor that has stopped oscillation operation and changing the corresponding slave microprocessor to oscillation operation according to the value of the received data. It is provided.

Means for Solving the Problems A serial data reception data register for receiving serial data transmitted from another microprocessor, a comparison data holding register for setting data by a processing program of a central processing unit (CPU), and the serial data Comparing the output value of the reception data register with the output value of the comparison data holding register, and sending an oscillation start signal when the output values match, and a micro comparator only when the oscillation start signal is input. And an oscillation control unit for starting the oscillation of the processor.

By doing this, when a system is constructed with multiple microprocessors, it is possible to easily reduce power consumption by turning on only the necessary microprocessors and stopping the oscillating operation of the idle microprocessors. Therefore, when the microprocessor in the idle state is operated, the oscillation start control can be performed only for the individual microprocessors.

Embodiment An embodiment of the present invention will be described in detail with reference to the block diagram shown in the drawings. The serial data reception data register 1 is always set by receiving data transmitted from another microprocessor, and the comparison data holding register 3 is set by the CPU holding this register by the processing program of this CPU. . The comparator 2 compares the value of the serial data reception data register 1 with the value of the comparison data holding register 3, and sends an oscillation restart signal to the oscillation controller only when the values match.

If the value of the serial data reception data register 1 and the value of the comparison data holding register 3 match during oscillation now, the oscillation restart signal is sent to the oscillation control unit, but the oscillation control unit Since this is originally set to the oscillation operation mode, the influence of this signal does not appear.

Next, consider the case where the oscillation is stopped. Since the serial data interface can receive data even when oscillation is stopped, it always receives serial data sent from another microprocessor. When the reception of one data string is completed, that is, every time the value of the serial data reception data register 1 is updated, the value of the comparison data holding register 3 is compared, and only when the values match, the oscillation control is performed. An oscillation restart signal is sent to the section, and the mode is automatically changed from the oscillation stop mode to the oscillation execution mode.

As described above, according to the present invention, when a system is constructed by a plurality of microprocessors, only the necessary microprocessors are set in the operating state and the oscillation operation of the idle state microprocessor is stopped. It is easy to reduce power consumption without wasting power, and when operating a microprocessor in an idle state, it should be used as a comparison data holding register for the microprocessor that should restart oscillation from another microprocessor. By transmitting the data of the same value as the serial data, it is possible to easily change only the microprocessor that requires the oscillation restart to the oscillation mode.

[Brief description of drawings]

The drawings are block diagrams showing an embodiment of the present invention. 1 ... Received data register for serial data, 2 ... Comparator, 3 ... Comparison data holding register.

Claims (1)

[Claims] 1. A serial data reception data register for receiving serial data transmitted from another microprocessor, a comparison data holding register for setting data by a processing program of a central processing unit (CPU), and reception of the serial data. A comparator that compares the output value of the data register with the output value of the comparison data holding register and sends an oscillation start signal when the output values match, and the oscillation of the microprocessor only when the oscillation start signal is input. And an oscillation control section for starting the oscillation control apparatus.