JPH01599A - Pitch generation circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a pitch generation circuit for a melody IC.

[Summary of the invention]

The present invention provides a pitch generation circuit for a melody IC.
oscillate at a frequency twice (K = integer) the frequency of 12 different pitches of xBn'' (n/integer), input that signal to a programmable counter, and set or reset the programmable counter using a decoder to divide the frequency. By changing the frequency ratio and further dividing the signal to a frequency of 17, all pitches of L octaves (L = integer) are generated.

[Conventional technology]

The pitch generation circuit of a conventional melody IC is as shown in Fig. 2, in which 51 is an oscillation circuit, 52 is a programmable counter, 53 is a frequency dividing circuit, 54 is a scale ROM,
55 is a main ROM, and 56 is an output terminal.

The scale R of 54 is determined by the data in the main ROM of 55.
The madres of the O gate has been decided, and accordingly, scale 1?
The data from the OM was output, set or reset to the programmable counter 52, changed the frequency division ratio, and shaped the waveform by the frequency division circuit 53 before being output.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional technology, the pitch created by the programmable counter can be changed by increasing the focus number.
It is possible to play more than three octaves without hitting a pitch, but scale L? Due to the capacity of the OM, the pitches that can be stored in the scale ROM are limited, and there is a problem in that only 15 to 20 pitches can be output at most. SUMMARY OF THE INVENTION The present invention is intended to solve these problems, and its purpose is to provide a circuit that has a simple configuration and outputs all pitches in a wide pitch range.

[Means for solving problems]

The pitch generation circuit of the present invention controls a CR oscillation circuit including a NAND circuit, a plurality of inverters, a resistor, a plurality of capacitors, a plurality of switches, a plurality of frequency dividing flip-flop circuits, a programmable counter, and the plurality of switches. A first decoder that controls the programmable counter, a second decoder that controls the programmable counter, and a ROM that determines the input of the decoder.

[Operation] According to the above configuration of the present invention, a capacitor is selected based on a signal from the ROM, and CI? The oscillation frequency of the oscillation circuit is determined, and the frequency division ratio of the programmable counter is also determined based on the signal from 120M, and a free pitch is derived from the combination of both.

〔Example〕

FIG. 1 is a circuit diagram in one embodiment of the present invention,
In the figure, 1 is a resistor, 2 is a NAND circuit, 3 and 4 are inverters, 5-16 are capacitors, 17-28 are selection switches, 29 is a buffer, 30-32 is a 3-bit programmable counter, and 33 is a frequency divider. flip-flop, 3
4 is a second decoder, 35 is a ROM, 36 is a first decoder, 37 is an inverter, 38 is a pull-down resistor 39 is an oscillation control terminal, and 4o is an output terminal. Resistance 1 and 5
A resistor of 1 and a capacitor of 5 to 16 are set so that the frequency of the 12 pitches of Cn=Bn" (n/integer) is oscillated by the capacitors of 1 to 16.
A signal from the OM turns on one of the switches 17 to 28 via the 36 16th decoders. The oscillation frequency, which is twice the frequency of one pitch among the oscillated Cn to Bn'', is input to 30 to 32 programmable counters.Signals from 35 ROMs transmitted simultaneously are as follows:
34 Set the programmable counters 30 to 32 through the second decoder, and set the input frequency to 1/2N (
N/integer). As a result, the octave is determined, and the waveform is shaped using 33 frequency dividing flip-flops.
Output from 40 output terminals. For example, if you oscillate 3.520 Hz with a CR oscillation circuit and do not divide that frequency at all with a programmable counter, you will get a pitch of 1,760 Hz (Aa) from the output terminal, and if you divide it by 172, you will get 880 H2. (A5) pitch is obtained. Similarly, if you divide the frequency by 1/4 and l/8, you get 44011z (8),
A pitch of 220 Hz (/h) is obtained respectively. That is, Cn=Bn", Cn/2~Bn"/2, Cn/4~
Any pitch from Bn''/4, Cn/8 to Bn''/8 can be freely selected.

〔Effect of the invention〕

As described above, according to the present invention, by determining the oscillation frequency and frequency division ratio using the ROM, it is possible to freely select and output all pitches in a wide pitch range.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the pitch generating path of the present invention. FIG. 2 is a block diagram showing a conventional pitch generation circuit. Applicant Seiko Epson Co., Ltd. 1 Figure 2 Figure 2

Claims (1)

[Claims] A CR oscillation circuit consisting of a NAND circuit, a plurality of inverters, a resistor, a plurality of capacitors and a plurality of switches, a plurality of frequency dividing flip-flop circuits, a programmable counter, a first decoder that controls the plurality of switches, and the programmable A pitch generation circuit comprising: a second decoder that controls a counter; and a ROM that determines an input to the decoder.