Signal generation circuit

A signal generation circuit comprising:

• central processing means for processing an output signal according to an operation program;
• at least one register connected to the central processing means through a data bus, for storing initial data as a reference for the output signal;
• memory means for storing the operation program and waveform data necessary to generate the output signal;
• address specifying means for specifying an address of the waveform data stored in the memory means according to the initial data stored in the register;
• signal processing means for processing the waveform data at the specified address on the basis of the initial data stored in the register in order to provide the output signal;
• and
• switching means for switching the data bus so that it electrically connects the central processing means and the memory means when an instruction from the operational program is to be read from the memory means into the central processing means, and so that the data bus electrically connects the signal processing means and the memory means when the waveform data is to be read from the memory means into the signal processing means.

A compressor controlling device comprising:

• signal generation means including,
• first read only memory for storing an operational program,
• second read only memory for storing waveform data corresponding to a plurality of motor rotation speeds,
• central processing means for addressing the operational program stored in said first read only memory and for addressing waveform data stored in said second read only memory,
• random access memory for receiving and outputting a rotational speed from an external controller, and
• waveform generating means for processing the waveform data addressed by said CPU in accordance with the operational program to generate a compressor control signal;
• photocoupling means for removing noise from a direct-current output;
• converting means for converting the direct-current output to a rectangular wave equal to a three phase alternating current according to the compressor control signal and the rotational speed stored in random access memory;
• and
• compressor coil means for receiving the three phase alternating current for controlling a rotation speed of the compressor.

A signal generation circuit comprising:

• random access memory for storing a rotational speed of a motor set by an external controller;
• read only memory for storing an operational program and waveform data;
• central processing means for addressing the operational program stored in said read only memory;
• waveform generating means for addressing and processing waveform data in accordance with the operational program to generate a compressor control signal used to control a motor such that its rotational speed matches the rotational speed stored in said random access memory;
• and
• line changeover means for operatively connecting said random access memory and said read only memory to said central processing means when the operational program is to read from said read only memory and for operatively connecting said random access memory and said read only memory to said waveform generating means when waveform data is to be read from said read only memory.