JPH0648243U - Serial-parallel conversion circuit - Google Patents

Abstract

(57) [Summary] [Purpose] The purpose is to easily initialize the latch circuit without receiving the initialization signal from the microcomputer. [Structure] The latch signal when the clock signal is at "H" level is used as an initialization signal.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention is a serial-parallel conversion circuit driven by a signal from a microcomputer process unit (hereinafter referred to as "microcomputer") used for an electronic volume for a graphic equalizer, an analog function switch, etc. The present invention relates to a configuration for initializing a circuit.

[0002]

[Prior art]

 FIG. 3 shows an example of a conventional serial-parallel conversion circuit. In the figure, 1 is a shift register, 2 is a latch circuit, 3 is an output circuit, 5 is a control circuit, 6 is a data input for receiving serial data from a microcomputer, 7 is a clock input, 8 is a latch input, and 9 is Clear input, 10 is a data output for sending parallel data to the next stage circuit, and 11 is a microcomputer.

In the serial-parallel conversion circuit as described above, in order to initialize the latch circuit 2, the initialization signal from the microcomputer 11 is directly input to the clear input 9 for initialization, and the latch circuit 2 is initialized. Was set to.

[0004]

[Problems to be solved by the device]

 However, such a serial-parallel conversion circuit is formed in one semiconductor chip and is resin-sealed to form a semiconductor device. In order to connect the semiconductor device and the microcomputer 11 to each other, they are arranged on a printed board and connected by a wiring pattern. Therefore, it is necessary to provide an output terminal for outputting an initialization signal to the microcomputer 11 and a clear input 10 which is an input terminal for inputting an initialization signal in the semiconductor device of the serial-parallel conversion circuit. Thus, in order to provide a terminal for connecting to an external circuit in the semiconductor device, a large chip area had to be used.

As a means of reducing the number of terminals, there is also a method of inputting pseudo data corresponding to a clear signal to the data input 6 for initialization. However, since this pseudo data is input as serial signal data, for example, inputting 8 bits of serial data into the data input 6 requires time to transmit that bit, and the number of processing bits This method was not suitable for serial-parallel conversion circuits, which are often used.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a serial-parallel conversion circuit that can easily perform initialization without receiving an initialization signal from a microcomputer. To do.

[0007]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention has a configuration in which the latch signal from the microcomputer is used as both the latch signal and the initialization signal depending on the level of the clock signal.

[0008]

【Example】

 FIG. 1 shows an embodiment of the serial-parallel conversion circuit of the present invention. In the figure, the same reference numerals as those in FIG. 3 denote the same or corresponding ones, and 4 is an initialization circuit. The serial-parallel conversion circuit inputs serial data from the microcomputer through the data input 6 and sets it in the shift register 1, then inputs the clock signal into the latch input 8 and sends the data to the latch circuit 2. . Therefore, when the latch signal is input, the clock signal becomes "L" level. Since the "H" level of the clock signal is not used in normal operation, this clock signal is used for resetting. That is, when the clock signal is set to the “H” level and the latch signal is input, this can be used as the initialization signal.

FIG. 2 shows a specific example of the initialization circuit of the present invention. In the figure, 21a and 21b are inverters, and 22a and 22b are NAND gates. With such a simple circuit configuration, when the clock signal is at the “L” level, the latch signal operates as a normal latch signal, and when the clock signal is at the “H” level, the latch signal is used as the initialization signal. You can Therefore, the microcomputer and the serial-parallel conversion circuit do not need a terminal for the initialization signal, and the latch circuit can be instantly set.

[0010]

[Effect of device]

 As described above, the initialization signal can be generated by the level of the clock signal from the microcomputer and the latch signal, so the program operation of the microcomputer is simple and the serial-parallel conversion circuit is also simple. Therefore, the chip area becomes smaller, and the degree of integration can be increased more easily. Also, since the initial value can be set instantly, there is an advantage that it can be effectively performed even if the number of bits increases.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a serial-parallel conversion circuit of the present invention.

FIG. 2 is a diagram showing a specific example of an initialization circuit in the serial-parallel conversion circuit of the present invention.

FIG. 3 is a diagram showing an example of a conventional serial-parallel conversion circuit.

[Explanation of sign]

 1 shift register 2 latch circuit 3 output circuit 4 initialization circuit

Claims (1)

[Scope of utility model registration request] 1. A serial-parallel conversion circuit for inputting a serial signal sent from a microcomputer process unit, converting the serial signal into a parallel signal by a shift register and a latch circuit, and outputting the parallel signal. Serial function characterized by having the function of initializing the latch circuit and selecting both functions depending on the level of the clock signal
Parallel conversion circuit.